ABSTRACT. In this paper, a finite planar FSS (frequency selective surfaces) based absorber structure is analyzed in terms of its radar cross section under plane wave incidence and compared with the corresponding infinite unit cell based design. It is observed that the performance of finite absorber structure deteriorates under oblique incidence of plane waves. This observation is further supported by analyzing the scenario when a planar structure is bent around a cylinder and in the process, a limit of conformability is defined. This limit is the maximum curvature (or upper limit of bent angle) beyond which the planar absorber, designed based on unit cell simulations, cannot be used for conformal applications. These observations are supported by scattering analysis of bent absorber for three different radii of curvature, in Ansys HFSS.

ABSTRACT. In this work the long-term problem of designing true ultra-wideband absorbers has been taken into consideration. This article presents a compact, ultra-wideband metamaterial absorber (MMA) using a single layer metal-backed substrate. Without using multiple layers, the wideband absorption has been obtained by intelligent selection of resonating structure. Unlike previously proposed broadband absorbers which are basically efficient polarization converter, our proposed design is a symmetrical structure to avoid any chance of polarization conversion. The structure is realized utilizing dual-broadband MMA structures embedded one inside the other with lumped resistances. The novelty of the proposed design lies in its fourfold symmetric nature which allows it to be polarization insensitive broadband absorber which is very rare in its kind. The fractional bandwidth of the proposed absorber is 73.83%. The proposed concept is expected to find its application in the design and development of high-performance absorbers suitable for use in thermal detection, cloaking, explosive detection, electromagnetic interference (EMI), radar cross section (RCS) reduction of objects and many other fields.

ABSTRACT. A graphene-based tunable dipole antenna and 2 x 2 dipole antenna array is presented at THz Frequencies. These antennas have outstanding properties e.g. miniaturization and frequency reconfiguration. Both the dipole antenna and dipole antenna array is designed from 1.67 THz to 2.5 THz frequency range. The simulated results for return loss, directive gain, and efficiency are presented for both the antenna at different values of chemical potential.

ABSTRACT. Optically transparent antennas have attracted considerable attention in the past few decades due to potential applications in solar panels and wireless communications. However, the designs are typically based on transparent conductive oxides, which suffer from low transparency, high cost and poor flexibility. In this paper, an optically transparent, mechanically flexible monopole antenna is presented, which has been realized through screen-printing of silver nanowires (Ag NWs) in high efficiency. The proposed monopole antenna has been printed on a 50-µm-thick polyethylene terephthalate substrate. The total size of the antenna is 12×12 mm2, and the operating frequency covers Ku- and Ka-band (18-40 GHz), which makes the antenna suitable for mm-wave applications including 5G communication. The antenna demonstrates excellent stability over 100 bending cycles with a radius of 4 mm. More importantly, 89% transmittance has been achieved at a wavelength of 550 nm, which is better than transparent antennas in literature.

ABSTRACT. In this paper, a dual feed compact circularly polarized microstrip antenna (CPMSA) is designed at 2.8 GHz using 3-dB hybrid coupler as feed network. The antenna size is reduced by 39.9 % by cutting slots in circular shaped CPMSA. Effect of cavity and radome is investigated on the performance of the antenna. Cavity and radome enclosure increases bandwidth (BW) and gain of antenna. Compact CPMSA provides 26.8 % BW for |S11| < -10 dB and 3 dB axial ratio (AR) BW of 27 % with maximum gain of 6.94 dBi at 2.8 GHz. Cross polar level of less than -15 dB and front to back ratio (F/B) of better than 12 dB are achieved for the compact CPMSA. The designed antenna is fabricated and experimental results agree well with simulated results. The designed antenna can be used as transmitter and receiver in transponder systems to monitor missile health parameters.

ABSTRACT. Application of slip cast fused silica ceramic radomes for missile applications is well known. But it suffers from certain limitations in terms of high temperature and rain erosion capabilities. This paper investigates the use of special metal tip to overcome the limitations without significant detrimental effect on radome electromagnetic performance. The performance is analysed with 3D EM simulations. The radome is fabricated with special process and performance is verified with measured results. The radome showed very low insertion loss and very low bore-sight error and cross-bore-sight error.

ABSTRACT. A compact light-weight profiled horn at K-band frequencies is presented in this paper. The feed assembly comprises a multi-mode profiled horn, a polarizer to generate circular polarization and a waveguide to coaxial transition. It has been manufactured using 3-D printed technology to reduce mass and cost. Measured results show good correlation with simulated results of a conventional machined feed assembly. The complete feed assembly weighs only 30 grams and is about 10 times cheaper than a conventional feed assembly.

ABSTRACT. In this paper, a square shaped ultrathin Metamaterial absorber for dual band applications in X-band have been proposed. The unit cell of this absorber is square in size and etched on one side of FR4 epoxy dielectric substrate. The proposed metamaterial absorber is ultrathin and conformal with thickness 0.25mm (λ/150, where λ refers to wavelength with respect to lowest resonant frequency). The proposed structure yields two diverse frequency at 8.01 GHz and 11.7 GHz with absorpties of 97.7% and 95.1% respectively. This absorber is insensitive to theta and phi variation. Stable response under oblique incidence is obtained for this absorber. The proposed structure is designed for dual-band applications in X-band

ABSTRACT. A simple U-shaped low profile ultra-wideband (UWB) antenna of dimension 0.37λL×0.25λL that offers extensive impedance bandwidth from 3 to 15.4 GHz (135%) is integrated to dual layered compact UWB frequency selective surfaces (FSS) that has unit cell dimension of 0.11λL×0.11λL only. The composite ‘antenna-FSS’ improves the gain variation by 3 dBi on an average in the unaltered antenna bandwidth with maximum gain of 8.6 dBi at 4.7 GHz. The composite ‘antenna-FSS’ structure also provides linearity in transfer function (S21) response and consistency in group delay response while placed in close proximity of a test bed that is made of dry and wet soil layers with a thin metal sheet, buried at mid-level.

ABSTRACT. In this paper, a method to design active frequency selective surfaces (AFSS) with the bandpass response in the lower frequency bands is proposed. The designed AFSS on a low cost 0.8 mm thick FR-4 substrate is capable to tune from 1.3 GHz-3.4 GHz in the TE mode of the impinging electromagnetic wave. The step wise step design procedure and its equivalent circuit model with the tuning capability has also been developed whose response is in close agreement to the proposed AFSS. To prove its novelty a state of the art comparison is also presented. Interestingly, the AFSS also tuned in the upper frequency band in the range of 9-13 GHz which along with the effect of angle of incidence and the measured results would be presented during the conference.

ABSTRACT. The dual-band frequency selective surface (FSS) of uniplanar compact electromagnetic bandgap (UC-EBG) microstrip patch antenna (MPA) is studied. The FSS is used for gain and bandwidth enhancement. Here, a surface with H-shape unit cell is used as the FSS superstrate which has been aperture coupled with the conventional MPA. This aperture coupled radiating MPA loaded by superstrate works as a resonant cavity antenna. The designed prototype has the passband characteristics at dual frequencies of 10.3 GHz and 16.5 GHz which lie in the X-band and Ku-band, respectively. A parametric comparison between the conventional MPA and superstrate-loaded MPA has been carried out. Gain enhancement of nearly 4dB is obtained after loading of MPA with UC-EBG superstrate. An improvement of 1.20% in the bandwidth is obtained.

ABSTRACT. In this paper, a new design technique to FSS band-pass radome with sharp band edge characteristics is reported based on substrate integrated waveguide technology (SIW). The radome is integrated with planar slotted waveguide antenna to study its effect on the radar cross-section (RCS) performance. The proposed radome significantly improves the radar cross-section (RCS) properties of the antenna at the operating frequency. Furthermore, the proposed radome wall shows very good transmission efficiency (90%) characteristics in the x-band region from 8.3 to 10.8 GHz with a very good insertion loss better than 0.2 dB. The fabricated prototype along with experimental verification proves the validity of the proposed structure for radome application.

ABSTRACT. In this paper, a method to interpret the transmission zero frequencies (fzs) in the stopband of a bandpass frequency selective surfaces (FSS) is presented. It is established that fzs depends on the surface current distribution on the FSS screen and is governed by the length of the FSS element on which the current density is stronger. Using this method, four fzs in the stopband of a novel FSS has been calculated which are: 5.90 GHz, 6.81 GHz, 12.95 GHz, and 14.42 GHz. Out of these fzs, the first two fzs reside below the -3dB cut-off frequency of the transmission bandwidth. And another two fzs resides above the -3dB cut-off frequency. Thus these fzs define a wide passband of the FSS which extends from 7.69 GHz to 12.16 GHz with a fractional bandwidth (FBW) of 45.16%. The position of fzs and the wide bandwidth of the FSS have been experimentally verified.

ABSTRACT. A true polarization conversion metasurface (PCM) based on reconfigurable ground plane is presented. The proposed structure can not only be utilized as a metallic ground plane but also it can be used as a PCM by switching the biasing state of PIN diodes. The simulation results reveal that with OFF state of diodes, the proposed ground plane can effectively convert linear-polarized incident waves into cross polarized reflected waves in the two different bands of 3.46–4.28 GHz and 8.55–11.32 GHz with a polarization conversion ratio of over 90%. Furthermore, the incident linearly polarized waves can be effectively converted into circular-polarized wave in the frequency range from 5.53–6.67 GHz. However, during the ON state of diodes, the proposed structure is tuned to a reflection characteristic like a metal plate. The magnitude of co-polarized reflection is over −1.5 dB from 1 to 15 GHz. The proposed reconfigurable ground plane has good potential applications in designing reconfigurable multi-polarization converter in polarization control microwaves devices.

ABSTRACT. In this paper, a novel hexagonal shaped frequency reconfigurable patch antenna is proposed which can be deployed in WLAN, mobile satellite communication and radio navigation. In this reconfigurable patch antenna design a hexagonal patch is connected to nearby two rectangular patches via PIN diodes allowing it to switch between four different frequencies( i.e., 5.27 GHz, 2.16 GHz, 5.45 GHz, 2.88 GHz and 5.76 GHz ). The proposed design provides 6.38 dBi gain and 435 MHz bandwidth when both diodes are in OFF state. Ansys HFSS is used for antenna simulation and a prototype with necessary biasing components and circuit has been fabricated and tested using Keysight Vector Network Analyzer N9925A.

ABSTRACT. A novel reconfigurable multifunctional four element Vivaldi MIMO antenna has been proposed in this paper. The Standalone Vivaldi Antenna has a impedance bandwidth of 3 - 10 GHz with a gain of 6 - 8 dBi . Tunable band notch characteristics with a tuning range of 3.5 GHz is obtained by placing varactor loaded SRRs on the slot-line and it can be further reconfigured into a tunable narrowband antenna by placing copper strip/ switches on the slot-line. Four such elements of this multifunctional vivaldi is employed to realize a 4-element planar MIMO antenna to reduce the multipath effects and also to get a multidirectional coverage. To achieve this, the antenna elements are sequentially rotated by 900 with respect to the adjacent element and feeding microstrip lines are placed orthogonally to each of them at the centre of the structure. The Isolation between the elements and the envelope correlation coefficient is well below -20 dB and 0.5 respectively. The other MIMO characteristics like Diversity Gain, Mean Effective Gain , Channel Capacity Loss are also well within the permissible level.

ABSTRACT. This paper demonstrates X-band periodically loaded meandered coplanar waveguide (CPW) structure based phase shifter built on Barium Strontium Titanate (BST: BaxSr1-xTiO3) ferroelectric substrate. CPW line has been loaded with 29 nos. interdigital capacitors (IDC) whose capacitance is varied with application of bias voltage, due to ferroelectric property of BST material. Design of IDC loaded meandered CPW line with integrated bias tee and DC blocking mechanism has been presented and analyzed using 2.5D electromagnetic solver. 800 phase shift and 4.8dB insertion loss at 10.5GHz for voltage range of 0-400V has been achieved in simulation. Scanning performance of 4 elements linear array has also been analyzed for maximum 800 phase shift. Designed phase shifter has been developed using 0.5µm thick BST layer with Ba0.6Sr0.4TiO3 composition has been realized using SolGel technique.

ABSTRACT. A planar ultra-wideband circular ring monopole antenna with reconfigurable patterns is presented. The proposed antenna consists of a circular ring which is used as a driver and two parasitic elements used as either reflector or director and eight p-i-n diode switches. The proposed antenna is designed to reconfigure its radiation pattern in such a manner that it can direct its maximum gain in a particular direction and minimizing the unwanted interference from the other directions without changing the impedance bandwidth of the antenna. By using the different states of the switches the three different operating modes of the antenna can be realized one is monopole and other are two directional mode with opposite directions. Due to the property of pattern diversity, it can enhance the front end flexibility in multipath environments and can be a good candidate for cognitive radio (CR) applications.

ABSTRACT. A novel dual-band frequency reconfigurable antenna is presented in this paper. Two discrete frequency bands have been achieved with the introduction of shorting pins along the edges of the patch. The planar antenna operates at 5 GHz Wireless Local Area Network (WLAN) and 5.5 GHz Worldwide Interoperability For Microwave Access (WiMAX) bands in state-1 and state-2 respectively, and the -10dB impedance bandwidth is 2.13% and 1.6% respectively. The antenna is successful in achieving a directional radiation pattern with an average gain of 5.66 dBi. This work presents an idea of achieving frequency reconfiguration by using the shorting pin loading technique. The designed antenna has a compact size of 40 × 40 × 0.762 mm3. The antenna is fabricated on a GML 1000 Substrate having permittivity ξr=3.2 and thickness of 0.762 mm. Good agreement is observed between the simulated and measured return loss data, thereby verifying the design structure. Moreover, the directional radiation pattern of the antenna helps in achieving high gain in both the bands, making it a suitable for WLAN and WiMAX band transmitters.

ABSTRACT. In this paper, two rectangular multi-band hybrid antennas are proposed. Modified Inter-digital structure slot is loaded on top of Dielectric Resonator Antenna (DRA) to achieve multi-functional capability for sub 6 GHz wireless applications. One is the tri-band hybrid antenna with modified inter-digital structure resonating at 2.93 GHz, 3.26 GHz & 5.5 GHz and consequent Return Loss (RL) bandwidths are 40 MHz (2.91-2.95 GHz), 60 MHz (3.23-3.29 GHz) and 230 MHz (5.37-5.6 GHz) respectively. The second one is a quad-band hybrid antenna resonating at 2.48 GHz, 2.84 GHz, 3.26 GHz and 5.5 GHz and resultant RL bandwidths are 40 MHz, 40 MHz, 60 MHz and 220 MHz respectively. The field analysis and parametric study of the proposed hybrid antennas are presented using Ansys-HFSS Electro-magnetic solver. The peak gains obtained for the proposed tri-band antenna are 6.2dBi, 6.4dBi, 5.5 dBi, and 5 dBi, 6.25 dBi, 6.5 dBi, 4.2dBi for quad-band antenna at all the resonances that have been occurred lower to higher bands sequentially.

ABSTRACT. This paper presents the design and development of broadband power divider which divides power in phase and equal from the Standard (WR-51) air filled waveguide to non-standard dielectric (Teflon) filled waveguides. The design uses Y-Junction and T-junction interconnection and a novel way to reduce the reflection at the dielectric-air interface for better S-parameter performance. The non-standard waveguide have dimensions of a (broad-wall) =12.95mm and b (narrow-wall) =4.5mm. The simulated and measured S-parameter performance of the power divider has been presented. The design is simulated using the High Frequency structure simulator (HFSS). The power divider can be used for dielectric filled waveguide fed antenna like slotted waveguide antenna.

ABSTRACT. This paper presents a method of independent control over the excited modes of a single mushroom resonator loaded SIW cavity. Circular and linear slots are introduced into the mushroom resonator by etching out metal from the patch of the mushroom. Angles of circular slots and length of linear slots are adjusted to change the surface current path of a particular excited mode and attain a desired frequency of resonance without disturbing the other mode. The fundamental mode of resonance, i.e. TE101 is shifted by 12.5% after changing one of the slot angles, θ by 60˚, whereas the next mode (TE102) remains unaffected. Keeping TE101 mode fixed, the 2nd mode of resonance (TE102) is shifted by nearly 7% after changing the other slot angle, φ by 30˚ and is also shifted by 4.5% after changing the length of linear slot by 6 mm. This independent control over the excited modes has significant applications in Wi-Fi technology, satellite communications and weather radar systems.

ABSTRACT. For fusion plasma, its density and temperature of electrons are the two most crucial parameters. There are various techniques, including microwave/millimeter-wave reflectometry, to measure these parameters. In a reflectometry set-up, transmitting and receiving antennas play a very important role. In this paper, design and optimization of a corrugated horn antenna suitable for plasma diagnostics in reflectometry/interferometry system is presented. The return-loss, cross-polar isolation, side-lobe level and gain of the D-band (110-170 GHz) horn are discussed with necessary graphs. To ensure the performance stability, sensitivity analysis is also included.

ABSTRACT. This paper presents the design, development and measured performance of a TE21 mode coupler in a circular waveguide having 7% coupling bandwidth. The mode coupler consists of a symmetrical branching network with two axially placed rectangular slots for coupling the TE21 mode, a wraparound E-plane power combiner and a circular iris as matching section. In order to use this coupler as monopulse tracking coupler another folded E plane power combiner has been added in TE21 mode coupler for coupling of TE11 mode. The simulated and measured results have been presented.

ABSTRACT. A comparative study has been done among all possible configuration of a double-Y balun. The comparison has been made in terms of their frequency domain response. Double-Y balun has an all-pass characteristic. Among all possible configuration of the double-Y balun, microstrip line to stripline transition from 100 $\Omega$ unbalanced line to 100 $\Omega$ balanced line shows the best response. This optimum double-Y balun shows all-pass characteristics over more than 10GHz bandwidth. An exponential taper is used to convert 100 $\Omega$ unbalanced impedance to 50 $\Omega$ unbalanced in microstrip line configuration and 100 $\Omega$ balanced impedance to 100 $\Omega$ balanced impedance in coplanar stripline configuration. This complete feed system can be used to feed a balanced planar Bi-blade antenna for ground penetrating radar application.

ABSTRACT. A four channel high power microwave rotary joint using oversized (overmoded geometry) concentric coaxial waveguides is proposed. The rotary joint is designed to consist of two channels operating at Ku-band and two channels operating at C-band. The simulated return loss, insertion loss and inter-channel isolation is presented with 360-degree rotation. The oversized geometry is most suitable for successful realization of a coaxial 4-channel rotary joint without having any RF and mechanical realization difficulties. This configuration allows for greater diameter for innermost channels which have larger lengths compared to outer channels as against conventional coaxial configuration where cavity dimensions are based on dominant mode operation only. A single channel prototype rotary joint is developed at Ku-band as proof-of-concept. The results are presented.

ABSTRACT. A novel multiple beam cascaded FW circuit that can enhance the gain and power of a TWT is presented in this paper. The cold test properties such as dispersion and interaction impedance of FW SWS has been determined using CST MWS Solver. Further, 3-D PIC simulation has been carried out for a three-stage FWTWT, which gives an output power of 25 watts and a gain of ~ 32 dB at 94 GHz.

ABSTRACT. Indian Space Research Organization (ISRO) has taken the research and developmental activities to develop the technologies for large unfurlable reflector antennas for space-borne LEO and GEO platform. The successful Research and development have culminated into the development of 6m offset parabolic reflector at S-band for GSAT-6 and 6A for multiple five spot beams over Indian land mass. The other successful development is related to 3.6 meter Cassegrain reflector antenna with 8 feeds at the focal plane with Butler matrix to generate 4x2 beam coverage on the ground for Synthetic Aperture Radar Applications at X-band. The on orbit performance of the both the types of antennas in GEO as well as LEO platform closely match the predicted performances.

ABSTRACT. The large unfurlable antenna technology is a key technology for a number planned future active and passive microwave remote sensing Earth Observation missions developed by the European Space Agency (ESA). After introducing their programmatic context, five future ESA missions, which may use this technology, will be presented. In particular, the different requirements for the reflector antenna will be explained. Finally, the technology pre-development for a Large Deployable Reflector for Earth Observation (LEOB) to address these needs will be described.

ABSTRACT. Oxford Space Systems (OSS) is developing a next generation of novel, deployable and scalable offset and cassegrain satellite antennas for the Synthetic Aperture Radar (SAR) market. OSS has developed a proprietary, pre-shaped composite membrane reflector surface. The membrane enables the reflector to retain a high accuracy parabolic profile, without the need for a complex and expensive cable shaping networks. OSS has also developed a scalable, patented outer-ring mechanism to support both pre-shaped membrane and proprietary mesh surfaces. These developments result in an offset reflector antenna that is lighter and more stowage efficient than conventional designs. OSS is currently building a flight unit scheduled for on-orbit demonstration in late 2020. The OSS Cassegrain architecture uses a variant of flight-proven, proprietary, flexible composite ribs wrapped around a central hub. This results in a highly efficient stowage form factor. The antenna’s primary reflector utilises a novel, proprietary metal-mesh surface and from initial testing undertaken by the European Space Agency, the mesh achieves higher RF performance than incumbent alternatives. To achieve this, the mesh is knitted as a single element, thus requiring only a single seam to a create ‘3D’ parabolic surface. This reduces surface errors, decreases manufacturing time and with further development, is anticipated to provide a route to volume production. This paper covers the technical challenges and innovations of both OSS antenna developments.

ABSTRACT. Two basic Large Reflector technologies, to meet different mission requirements, are under development in Thales Alenia Space Italy. The Large Deployable Reflector (LDR) technology adopts mesh reflecting surface and can afford very large offset optics (up to 18 m) up to Ku band. The LDR is a patented design which should allow for the development of European Radiometric and Earth Observation missions. A 6 meters LDR demonstrator, fully representative of the design with dummy mesh, has been manufactured and tested to demonstrate the whole deployment kinematic, deployment accuracy and surface repeatability. These activities have been initially carried out within the ESA ‘Innovative, Scalable, Large Deployable Antenna Reflector’ 108005/13/NL/CP contract and continued with internal R&D funding. The Large Unfurlable Reflector Assembly (LURA) technology is focused on large onset optics (5 to 7 m) based on solid unfurlable petals for wide band application from C up to Ka band. The LURA shall serve as a key component for Earth Observation missions. The axially symmetric configuration is suitable to be accommodated directly on the earth facing panel thus allowing to use small platforms and small launchers. The wide band operating frequency (C to Ka) is permitted because of the high surface accuracy, good reflectivity and high thermal stability. A 5 meter LURA demonstrator, fully representative of the real design, has been manufactured to demonstrate kinematics, deployment accuracy and repeatability. The whole reflector assembly is being qualified.

ABSTRACT. Subsystems for satellites are subject to constant improvements in terms of precision, higher performance, lower package size and mass demands. This is exactly also a case for two types of missions: Earth Observation (EO, for the sustainability of nature and mankind) and Telecommunication (TC, for business and global connectivity). Technologies of Large Deployable Reflector Subsystems (LDRS) are owned only by a few suppliers worldwide and are therefore called “critical technology” from nondependence point of view. With an innovative space approach, where a “nothing-is-impossible-motto” is unfolding engineers’ power, the consortium “WeLEA” consisting of 15 companies out of 7 European countries under the lead of HPS-Germany is developing the European product “Large European Antenna” (LEA), co-funded by the European Commission (EC) and complementary funded under contract of European Space Agency (ESA). LEA comprises reflector, arm, hold-down mechanisms, thermal hardware and electronics. A first 5-meter class Proto-Flight Model operating in X-band (LEA-X5) of the LEAfamily is under manufacturing and to be tested until the end of October 2020, reaching a Technology Readiness Level (TRL) of 8. The PFM will be offered on the global open market of planned space missions at no charge in exchange for a free ride up into space in order to realize the final in-orbit verification. The production of another 8 meter Engineering Model (LEA-K8r) for Ka-band applications rotating for conical scanning radiometry with 8rpm on top a satellite, will be kicked-off in January 2020.

ABSTRACT. In this paper, a printed dipole antenna with metamaterial loadings on both sides of the dipole for future generation 5g wireless applications is presented.The meta-material unit cells are placed at an optimized distance from the dipole arms on the top and bottom planes. The antenna is fed by a 50 ohm microstrip line over a truncated ground plane associated with it. The resulting antenna is seem to be compact with the size of 17×24mm2 . For the return loss of -10dB, the antenna shows the impedance bandwidth of 24 -40 GHz. The peak gain of the dipole antenna without meta-material was 5.5dBi. The meta-material loading on the dipole has resulted in the improvement of gain by approximately 2dBi, the resulting peak gain of overall design was 7.5dBi. The large impedance bandwidth, compact physical size and the resulting gain of the proposed antenna makes it viable for mm-wave 5G wireless applications.

ABSTRACT. A Dual-band Dual-sense square slot antenna is presented in this paper. The proposed antenna consists of a modified L-shaped patch with truncated at horizontal strip to get the circular polarized (CP) band at higher frequency region. On the opposite side of the substrate two semi-hexagonal notches is etched from the lower boundary of the ground plane in order to increase linear polarized (LP) impedance bandwidth at lower frequency region and an array of rectangular strips at an angle 45⁰ with respect to centre is added on the ground plane in order to also increase ARBW. The design and performance of a dual-band circular polarized antenna for multisystem application are described in this paper. After optimization of the geometrical parameters for the antenna, the resonances are merged, and thus a dual impedance bandwidth is obtained. The simulated impedance bandwidth at S11<-10dB ranges from 3.48 – 5.85 GHz, 6.10 – 10.82 GHz. The simulated dual axial ratio bands are 550 MHz, and 1090 MHz at centre frequency of 6.3 GHz, and 9.7 GHz respectively. The radiation characteristics of the implemented antenna are also presented and discussed.

ABSTRACT. The radome acronyms words radar and dome for communication systems. Radome is protective cover for Antenna systems while preserving the microwave properties of the communication system. It provides protective interface between the missile tracking system and the atmosphere. It is aerodynamically efficient and minimally obstructive to radar tracking signals in the radio frequency band. New missile performance capabilities to cater speed mach4 to mach5, will render conventional radome design standards inadequate and lead to the experiment of new materials. Thus, interest in radome development is being renewed, and radome designers are being challenged to advance the state of the art materials for radome applications. Materials play an important role for design and high performance of the radome. This article explains some of the important aspect of the radomes materials like ceramic and polymers for high speed, high frequency and high performance radome applications. The ceramic and polymer composite will also be discussed radome applications

ABSTRACT. Analysis and design of switched beam phased array antenna at millimeter wave frequency is described in this work. To achieve proposed phased array antenna first we have designed an inset feed patch antenna at 35GHz. A passive beam switching network, Butler Matrix, is modelled at 35 GHz where output of the designed beamforming network is fed to linear 1X4 antenna array to scan at angles 45°, -45°, 15°, -15°. The proposed structure is modelled and simulated in HFSS 3D EM simulator.

ABSTRACT. Internet of things (IoT) applications require orientation insensitive wireless devices to maintain stable and reliable communication as well as the positioning capability using the Global Positioning System. For those reasons, antennas providing near-isotropic radiation patterns along with wide far-field sphere polarization coverage, including linear and right-hand circular polarization, are highly demanded in IoT applications. In this paper, we present some theoretical limitations on the synthesis of an antenna with near-isotropic radiation and polarization patterns. We consider two models: a set of orthogonal Hertzian electric dipoles located at different points, as well as a model of Hertzian magnetic dipoles located on faces of a perfectly electric conducting cube. These models allow synthesizing the near-isotropic radiation and polarization patterns of an antenna based on short dipoles, as well as a cubic antenna with radiating patches on the cube faces.

ABSTRACT. A compact design of rectangular microstrip patch antenna (RMPA) is presented for its improved cross-polarized (XP) radiation properties. This is achieved by suppressing the spurious higher-order modes of the patch. In here, the non-radiating edges of the patch are partially shorted to the ground plane through metal stubs. This enables a design technique without perturbing the radiating patch or the ground plane. About 16 dB suppression of XP radiation in the H plane has been achieved without disturbing the co-polarized peak gain value. The spurious higher-order mode has been eliminated. The proposed design has been validated experimentally using a set of fabricated antenna prototypes. Measured results are nicely corroborated with the simulated data.

ABSTRACT. This paper reports the design, development and experimental characterization of spoof plasmonics based band-pass filter (BPF) using T-shaped resonator and metamaterial particles. The operational behavior of slow wave spoof SPP based T-shaped resonator has been explained through even-odd mode analysis. For input/output coupled feed, a corrugated groove based slow wave transmission line has been used. Further, by etching metamaterial particles in T-shaped resonating structure, lower operating frequency, better matching and higher selectivity is achieved with the same physical dimension. The design filter has single band response with center frequency f0 of 3 GHz. Measured insertion loss is around ~3 dB and return loss is better than 10 dB for the pass-band. The proposed filter has two transmission zeroes at both side of the pass-band located at 2.97 GHz and 3.2 GHz which enhance the selectivity of the pass-band. The 10 dB out of band spurious rejection bandwidth of the designed filter is 4 GHz (3.2 GHz-7.2 GHz) which is >2f0. The proposed filter will pave an important role in the design and development of plasmonic circuits and systems.

ABSTRACT. We present a dual-band electromagnetic energy harvesting surface that is designed for absorbing electromagnetic energy in the GSM-1800 and Wi-Fi bands. The unit cell of the periodic structure incorporates two bow-tie dipoles and a resistive load demonstrating excellent absorption characteristics with minimal dielectric losses. We also demonstrate how the proposed surface can increase the rectenna phsyical area and the collected power per rectifier, leading to viable energy harvesting applications in low power density environments.

ABSTRACT. In today’s era of communication, Substrate Integrated Waveguide (SIW) are being a major part of development in Microwave and millimeter wave frequency range applications. In this paper, a novel design of H-plane SIW horn antenna is proposed for Ku-Band applications such as landing systems of an Aircraft radar, fixed satellite broadcast services etc., The proposed design of antenna is focused on producing high bandwidth with variations in the tapered sections of the horn with respect to the conventional Hplane SIW horn antenna design. The design is simulated using the Keysight EMPro© 3D EM Simulation Software using FEM computational technique. Simulation results are analyzed, plotted and tabulated for various antenna parameters and are comparatively studied for conventional and modified structure respectively.

ABSTRACT. Regular monitoring and tracking of the temperate glacier and polar ice sheets are necessary because of their potential impact on climate change and sea level rise. In this paper, we analyze the airborne 10 MHz bent wire ground penetrating RADAR antenna using different materials. 10 MHz GPR antenna is simulated using different materials such as silver, copper, gold, aluminum, tungsten, zinc, brass, bronze, tin, chromium, indium, lead, titanium, iron, nickel, cobalt, cast iron and graphite. From the simulation results, it is evident that, the conductivity of the material and the radiation efficiency of the antenna are directly proportional to each other. And also, if the relative permeability of the material increases, the radiation efficiency decreases. The S11, VSWR, peak gain and the radiation efficiency of the bent wire GPR antenna are presented for different materials at the solution frequency of 10 MHz.

ABSTRACT. In this paper, a novel rectangular patch antenna with truncated ground structure (TGS) for 5G application is proposed. The designed antenna can work in the band of 19.537GHz to 44.656GHz for higher 5G frequency bands, with an impedance bandwidth of 25.119GHz. In addition to impedance bandwidth, gain and the radiation pattern of the proposed antenna are also presented and discussed. The minimum gain of the antenna throughout the impedance band is 4.25 dBi, and the maximum gain is 10.45 dBi. The antenna is simulated using CST microwave studio 2019 software. Rogers’ RT6002 is used as a substrate of the antenna. The proposed antenna can work worldwide for the higher frequency band (26.5GHz -42GHz) of 5G.

ABSTRACT. A fractal antenna with modified partial ground is designed. It consists of modified feed and modified ground plane. It has an operating impedance bandwidth ranging from 4.8-18.1GHz (116%) and peak gain 4.5dB. For bandwidth enhancement modified CPW feed and modified ground structure is used. The overall substrate volume is 16.5×9.2×1.524 mm3. It has advantages of wider bandwidth, compact size, and desirable radiation characteristics.

ABSTRACT. The effect of superstrate material on microstrip patch antenna is established. Engineered superstrate is placed at certain height from patch antenna such that spherical diverging wave is converted into converging plane wave and gain enhancement in broadside direction is obtained. To verify the simulated results, the proposed prototype is fabricated and measured. An enhancement in gain of 7.84 dB is observed in broadside direction using a single layer of superstrate at the design frequency of 9.48 GHz.

ABSTRACT. In this article, a modified compact coplanar waveguide (CPW) fed printed ultra-wideband (UWB) antenna is proposed that is useful for various indoor and outdoor limited range wireless communication applications. The antenna offers an improved impedance band from 2.45 to 27.25 GHz (167%), covering the unlicensed UWB of 3.1-10.6 GHz. The antenna patch is modified by upper half cut of circular patch with CPW-fed line, and bended ground plane. The antenna is fabricated on 0.8 mm thick FR4 epoxy substrate. The projected antenna structure has a gain variation of 1.5-5.5 dBi, radiation efficiency variation from 55-90%, and monopole like non-directional H-plane and bi-directional E-plane radiation pattern.

ABSTRACT. Microstrip antennas have been one of very attractive field of research in the recent years. They have become very important component in many futuristic wireless communication systems. Requirements of wide band / multiband operation have resulted in many advanced research in the field of antennas. The paper describes a design and simulation of tri band microstrip patch antenna. The antenna geometry has been loaded with three slots in the radiating element to obtain tri-band operation. The proposed antenna has been designed on 30 mils Roggers RT Duroid 5880 substrate having dielectric constant 2.2 and loss tangent 0.0009. The antenna has been simulated using ANSYS HFSS full wave solver using proper boundary conditions. The antenna resonates at three frequencies 11.65 GHz with 800 MHz bandwidth, 13.95 GHz with 1.8 GHz bandwidth and 17.0 GHz with 600 MHz bandwidth for return loss better than -10 dB. The antenna can replace three antennas being used on UAV platform. The designed antenna can be used for Ku band satellite communications in which Rx and Tx operating frequencies are 11.3 and 14 GHz respectively. The third frequency band can be used for line of sight communications between airborne and ground terminal.

ABSTRACT. A novel reconfigurable polarization converter based on PIN diodes controlled metasurface is presented. The proposed structure can be reconfigured between conversion mode and reflection mode by changing the biasing state of PIN diodes. The unit cell of proposed structure is comprised of a single split rectangle ring resonator, two cut wires printed on a dielectric substrate, backed with metallic ground sheet. The simulation result reveals that the proposed metasurface can effectively convert a linearly polarized (LP) incident electromagnetic (EM) wave into its orthogonal linearly polarized (LP) reflection wave in a lower band of 6.66–10.51 GHz with a polarization conversion ratio over 88%, and a circularly polarized (CP) reflection wave in a higher band of 12.2–14 GHz with a axial ratio below 3dB during OFF state of diodes. On the other hand during the ON state of diodes, the propose structure exhibits total reflection characteristics over the operating band and behaves like a reflecting metal plate. The proposed metasurface has good potential applications in a linearly and or circularly polarized antenna as a superstrate, making the polarization of the antenna reconfigurable.

ABSTRACT. A comparative study has been done among the possible configuration of the dual-frequency resonators. Optimum design of a resonator structure combining elliptical spiral resonator with circular resonating elements has been proposed. The resonant frequencies of the proposed resonator are 0.582 GHz and 1.338 GHz. This resonator can be used for Ground Penetrating Radar application and medical application such as non-invasive glucose monitoring.

ABSTRACT. In this paper, A substrate integrated waveguide (SIW) cavity backed slot antenna for broad-band and millimeter-wave wireless communication applications, shape of the slot is flower inserted on top of the substrate and feed used is microstrip. The antenna is printed by RT-Duriod 5880 substrate with relative permittivity of 2.2, thickness is 0.381mm and size is 15mm x 10.7mm. The antenna is simulated, fabricated and tested the results using a vector network analyzer (VNA). The measured impedance bandwidth is 5.4GHz (58.6GHz to 64GHz) with two resonant frequencies are 59.7GHZ, 63.36GHz and good radiation patterns are observed at resonant frequencies. The equivalent circuit model is introduced to match the proposed antenna reflection coefficient, VSWR and matrix laboratory (MATLAB) is used to analyze the response of the circuit and also introduced mathematical equations for far field patterns

ABSTRACT. In this article, Dual-band miniaturized and modified circular patch (MCP) antenna for Wi-Fi and WLAN is designed and investigated. The proposed antenna architecture has a compact size of 14*16*1.6 mm3. The antenna structure is printed on the front side while finite ground plane is etched out on the rear side of the FR4 substrate. Dual frequency band is obtained due to addition of rectangular strips in the patch. The parameters of the patch and the finite ground plane are optimized to get dual frequency band at 2.4/5.8 GHz band of WLAN. The gain is 2dB at the frequency band of 2.4GHz and the peak gain of the proposed antenna is about 3.1dB at the frequency band of 5.8GHz. The peak radiation efficiency of the proposed antenna is 70% at lower band and 65% at the higher band is achieved. The antenna structure has a stable omni-directional and bi-directional radiation patterns at both the desired frequencies. Simulated and measured Co-pol. and Cross(X)-pol. of the antenna are in relatively good agreement.

ABSTRACT. RF energy harvesting (RFEH) is one of the solutions for the renewable energy sources. RFEH can provide energy to low power devices wirelessly with the help of antenna and rectifier. In present times the devices are small and compact therefore it requires the compact antenna. The hybrid fractal antenna is used in this paper for the RFEH is a miniaturized design. Genetic algorithm (GA) is used for optimizing the hybrid fractal antenna for the 2.45 GHz frequency. Curve fitting approach is used to develop an equation which relates the resonant frequency to the dimensions of the antenna and this equation is used as objective function of GA. The antenna gain of hybrid fractal antenna is 6.21 dBi with the antenna efficiency of 77.9 %. This proposed hybrid fractal antenna has resulted in size reduction of 52.47 %. The experiment and simulated results are in good agreement. This antenna can be used for the RFEH applications in the ISM band.

ABSTRACT. This paper investigated and presented a novel reactive stub loaded square microstrip patch antenna for circularly polarization at C-Band. A square patch antenna is designed and loaded with inductive and capacitive reactive stubs. The phase difference due to different electrical lengths of two stubs provides near to 90 degree phase quadrature for circular polarization. The antenna is designed on PTFE substrate (εr =2.2, tan δ =0.0009) with thickness of 61 mil. Optimized the design using commercial EM software, feed point location and stub length & widths are varied to achieve optimum reflection coefficient and circular polarization bandwidths. The antenna shows 7.2% impedance bandwidth, 3.3% of Axial Ratio (AR) bandwidth and 6dBiC peak gain. It is proposed to use for altimeter applications.

ABSTRACT. In this paper, a straight probe fed and an L-probe fed rectangular patch antenna in the ultrahigh frequency region have been investigated. The 2:1 VSWR bandwidths of 38.49% and 46.17% have been achieved using the straight probe and the L-probe fed patches, respectively. Characteristic Mode Analysis (CMA) of the designs have been performed using the EM solver FEKO to identify the contributing modes for the wide band behavior of these antennas.

ABSTRACT. This paper investigates effect of various types of aperture tapering on grating lobe level (GLL) of array antenna. Formulation of farfield pattern computation of array antenna with sub-array for required scan angle is discussed. Study has been performed for S-band 16 elements coaxial fed microstrip array antenna, excited with 2 elements sub-arrays. Symmetric linear aperture tapering, symmetric raised cosine type aperture tapering and (cos + sin) type asymmetric aperture tapering is applied on array elements and the farfield patterns and its parameters including grating lobe is computed and studied for 10degree beam scan. The presented study is applicable to any size of array antenna and its conclusions can be generalized to design array antennas.

ABSTRACT. A wideband design technique of a Fabry-Perot cavity antenna (FPCA) is presented based on Particle Swarm Optimization (PSO) algorithm. The proposed method appears to be very efficient as the optimization technique is driven by commercial electromagnetic simulator. Ten antenna parameters have been handled successfully to achieve a wide band optimized result. About 16.8 dBi maximum broadside gain has been achieved using the optimally designed antenna. Peak gain is maintained above 11 dBi over the 50% impedance bandwidth of the antenna.

ABSTRACT. In this paper, a Cylindrical Dielectric Resonator (CDR) loaded printed antenna is presented which is excited by the microstrip feeding technique and is suitable for Cognitive Radio applications. The proposed antenna consists of a leaf-shaped Ultra Wide-Band (UWB) antenna and one reconfigurable antenna. By changing the switching conditions of PIN diodes, the frequency hopping occurs in different ranges of frequencies over 3-11 GHz with suitable gain. The proposed structure operates under the interweave network paradigm. In this paradigm, sensing antenna senses the void spaces available in the spectrum, and the communicating antenna is used for transmission in these void spaces.

ABSTRACT. In this paper, two robust machine learning (ML) prediction methods, Gaussian Process Regression (GPR) and Artificial neural network (ANN) are used to predict the resonant frequency of square patch microstrip antenna (SPMA) with an equilateral triangular defect in the ground. The designed antenna can work in the band of 5.9206 GHz to 25.7625 GHz for the C, X ku, K band applications. By varying size of the square patch and triangular DGS , a total of 125 data samples were collected through simulation process using CSTTM, and out of which 105 data samples were used to build two ML models. For validation the authentication of these models, 20 data samples were used. After preparing the model, testing is done for 20 data sets and result obtained from ANN, and GPR model were compared with simulated resonant frequency and found that the GPR model gives better result than the ANN model. The predicted outcomes show that ANN and GPR models can be used to predict the resonant frequency of SPMA in the range of 5.9206 GHz to 25.7625 GHz.

ABSTRACT. In this paper, we propose a magnetostatic solver based on surface integral equations to understand the magnetic phenomenon arising in the indoor navigation problems. The assumption are that there are no current sources and the magnetic object is placed in a uniform magnetic field. The results obtained are bench-marked against analytical expression for a simple example involving sphere. The numerical results supports the validity of the proposed approach.

ABSTRACT. A planar beam steerable antenna array using the Substrate Integrated Waveguide technology is proposed in this work. Five slotted waveguide sections are clubbed together to form the antenna array, which ultimately transforms the radiation pattern to a directive one in both the planes. With change in the phase difference of the excitation signal at the feed, electronically steerable beam with a steerable angle of ± 15⁰ is obtained, with a boresight gain of 18.56 dBi.

ABSTRACT. The X-band Substrate Integrated Waveguide (SIW) antennas with different radiating slots etched on top layer is presented in this paper. The main objective is to evaluate the performance of five different antennas on the basis of standing wave ratio, return loss and bandwidth. The SIW structures are designed with Square Ring, U-shape, Inverted U-shape, C-shape and Inverted C-shape slots. This results the design in compact and planar structure. It is observed that the square ring slot antenna provides excellent return loss of -39.78 dB and VSWR of 1.03 at frequency 10 GHz and the C-shape slot antenna achieves very broad VSWR<2 bandwidth of 2.4 GHz. HFSS simulation software is used to carry out the simulation for the proposed antennas.

ABSTRACT. A Substrate Integrated Waveguide (SIW) inspired H- plane sectoral horn is presented in this work. A front dielectric load is incorporated in the design, which has been perforated by air vias, arranged in a circular fashion, for improved matching from the antenna to free space. This design operates at 21.36 GHz with a gain of 10.19 dBi bearing overall dimensions of 57 mm × 38 mm. The overall structure is etched on a single substrate and is fed coaxially with a standard SMA based connector model, making it a low cost solution for high gain antenna design.

ABSTRACT. In this paper, a dual-band substrate integrated waveguide (SIW) antenna loaded with composite right/left-handed transmission line (CRLH-TL) unit cell is presented. Initially, a modified interdigital capacitor (IDC) CRLH-TL unit cell was designed, which generates the dual-band. Two-unit cells are loaded in SIW based antenna that works in a common and a differential mode of operation. The proposed modifications is meant for further antenna size reduction, improved bandwidth. Additionally, two λg/4 resonators and a shorting pin are employed to suppress the harmonics, and for improved impedance matching. The measured results show an impedance bandwidth (|S11| < –10 dB) of 14.2 % (2.5 – 2.88 GHz) and 6.69 % (4.68 – 4.94 GHz) at the resonant frequencies of 2.68 and 4.78 GHz. The maximum measured peak realized gain and radiation efficiency of the designed antenna are 4.49 dBi, 66.87% for the first resonant frequency; and 5.48 dBi, 74.36 %, for the second resonant frequency. The measured results are quite in agreement with the simulation results.

ABSTRACT. A Compact microstrip feed cavity backed glass shaped substrate integrated waveguide slot antenna is proposed for millimeter wireless applications, slot shape and operated in 60GHz band that is ranges from 57 to 64GHz frequency band. The proposed antenna is simulated, tested, validated and also produces good radiation patterns. The proposed design as an impedance bandwidth of 7GHz that is operated frequency from 57 to 64GHz with reference of S11= -10dB line and also introduces RLC equivalent model is developed with MATLAB with transfer function based analysis to validate the reflection coefficient of the design and introduced mathematical equations of proposed design far field patterns

ABSTRACT. Design and analysis of multiband slot antenna using SIW technology explained in this work. This antenna is designed and simulated using High frequency structure simulator (HFSS2016) software and it uses substrate integrated waveguide technology with three different radiating slots with a cavity back side to produce resonance. The proposed structure radiates at three different frequencies 4.21GHz, 5.21GHz, 5.8GHz useful for wireless communication applications. It consists of one annular slot and two transverse slots and are fed with a coaxial probe, two distinct microstrip lines and higher isolation (i.e., <-20dB) can be achieved among the ports, which realizes a multiband functionality. Moreover, the antenna shows a gain values of 7.5dB, 6.7dB, 7.5dB at the three resonating frequencies.

ABSTRACT. A metal-only reflectarray designed at a center frequency of 12.5GHz has been presented with simulation results. It avoids the use of dielectric substrate and is less susceptible to environmental conditions. A gain of 32.5dBi, aperture-efficiency of 66.2%, beam-width of 4°, and a 1dB gain-bandwidth of 13.6% are achieved at 12.5GHz. It is suitable for use in Ku band DTH reception applications with linear polarization.

ABSTRACT. This paper presents the design and analysis of a broadband polarization reconfigurable PGMS reflectarray antenna. The proposed design offers multiple polarizations including circular polarization (CP) and linear polarization (LP), by simply rotating the linearly polarized feed antenna. The metasurface reflectarray of size 425x425mm^2 produces a gain of 30 dB at the designed frequency of 10 GHz. The feed antenna rotated at an angle of 45 deg will give LHCP wave while 135 deg rotation will give an RHCP wave. At an angle of 0 deg and 90 deg rotation, the design will give LP waves. The 3 dB axial ratio bandwidth for the circular polarization is 33.4%.

ABSTRACT. This paper presents a compact left hand circularly polarized patch antennas with multiple asymmetrical v shaped slits and cross slots for X and Ku band frequency range. The simulated patch antennas are resonating in between 10.8 GHz to 12.25 GHz. The varying lengths, widths and circumference of the slots/slits and also the position of them on the patch will be crucial in achieving circular polarization. Three different antennas with V shaped slits at the corners, V slits along with circular slots and cross slots etched on the patch antenna are presented. The obtained average simulated gain of the patch is about 7 dBi. The LHCP antenna is having an impedance bandwidth of about 16% and axial bandwidth od 3.1%. These proposed antennas are good for space communications, earth exploration and DBS applications.

ABSTRACT. This paper presents the design and experimental evaluation of a wideband reflectarray antenna using stub-loaded inverted E elements. A reflectarray of size 200 × 200 mm2 with 18 x 18 such elements is fabricated and measured for its radiation patterns. Through simulation-based study, two optimal gain-bandwidth performances are shown to be achievable by varying the focal distance and inter-element spacing values. In case 1, a 3-dB gain-bandwidth of 40% is observed with a peak gain and an aperture efficiency of 23.6 dBi and 28%, respectively. In case 2, a 2-dB gain-bandwidth of 32% is noted with a peak gain of 25.2 dBi and an aperture efficiency of 42%.

ABSTRACT. There have been significant interest in reflectarray antennas in recent years. The latest research have shown that reflectarrays can be used to provide solutions which are not possible using conventional technologies. In this paper, we present a general design framework for the design of advanced reflectarrays and show how it can be used to design antenna systems for future space-borne applications.

ABSTRACT. For efficient integrated design and analysis of antenna systems consisting of waveguide harness, feed horns, and electrically large reflectors, a hybrid software has been developed. Herein, a higher-order Methods of Moments formulation using the Multi-Level Fast Multipole Method and a set of dedicated algorithms for solving electromagnetic problems inside waveguide geometries are combined with Physical Optics and a set of optimization algorithms. This allows for direct optimization of the complete antenna systems based on the far-field performance.

An example illustrating the superior antenna designs achievable with this approach compared to traditional approaches, in which the components of the antenna system are optimized individually and then combined into a complete system, is presented.

ABSTRACT. The design and performance of a quad-band circular polarized monopole antenna for multisystem application are described in this paper. A triple strip monopole antenna which is fed at the microstrip line, on the opposite side of the substrate a ground plane with a square loop slot, and two slotted stubs placed across the diagonal line of the square loop, is designed and fabricated to excite several resonances. After optimization of the geometrical parameters for the antenna, the resonances are merged, and thus a wide impedance bandwidth is obtained. The measured impedance bandwidth at S11<-10dB ranges from 4.63 – 5.47 GHz, 6.08 – 6.59 GHz, 8.26 – 9.59 GHz, 10.05- 10.42 GHz, and 11.81 – beyond 15 GHz. The simulated quad axial ratio bands are 217 MHz, 269 MHz, 223 MHz, and 564 MHz at centre frequency of 5.3 GHz, 9.0 GHz, 12.1 GHz and 13.8 GHz respectively. The radiation characteristics of the implemented antenna are also presented and discussed.

ABSTRACT. A simple microstrip coupled cylindrical dielectric resonator antenna (CDRA) is capable of resonating at several frequencies, among which a few resonances (modes) exhibit excellent radiation characteristics. For a CDRA of high dielectric constant (r = 24), in addition to the dominant HEM11 mode, the HEM21 mode is excited as the second mode, and the HEM12+3 mode as the third mode. The third mode is of great interest as it produces broadside radiation with a peak gain of ~ 9.8 dBi, which is about ~ 3.9 dB higher than that of the first mode and ~ 5.4 dB higher than that of the second mode. In measurements, a peak gain of 9.4 dBi has been verified for the HEM12+3 mode.

ABSTRACT. A simple, low cost, small size printed microstrip-fed elliptical slot ultra-wideband antenna having band-notched response are proposed in this paper. By incorporating concentric elliptical arc within the elliptical shaped slot the band notch response is realised. The proposed antennas are optimized using IE3D, fabricated on low cost FR-4 substrate with dielectric constant 4.3 followed by measurement. The measured results indicates that the proposed antenna having dimensions of 60 × 60 × 1.6 mm3 has a impedance bandwidth over the frequency range 2.15-10.6 GHz with Return Loss ≤ -10 dB, except 2.8-3.6 GHz with elliptical slot with concentric elliptical arc. The proposed antenna shows stable gain, almost omnidirectional radiation pattern, insignificant group delay variation in the passband frequencies. Acceptable results are achieved in frequency as well as time-domain analysis for antenna.

ABSTRACT. Very low profile, wideband printed bowtie dipole dual-polarized aerial is offered for wideband BTS. A flared bow tie dipole with shorting post with Teflon spacer is proposed to attract low-profile geometry. The design incorporates a Pair of orthogonal printed flared bow tie dipole with shorting post with Teflon spacer is proposed to attract low-profile geometry and fed with a two coaxial cables and ground plane with air dielectric is used to obtain the high gain and directional stable emission model. The designed Massive MIMO aerial element is designed and optimized on RT Duroid 5880 substrate is working for less than 6GHz (3-5.0GHz) for 5G BTS applications. From the simulation results the single aerial element with flared section on the dipole arms yields an |S11 | less than −15dB impedance properties of 45.95% (3.12-5.32 GHz) , HPBW of 71.5 degrees and a gain of 9.2dBi, with Isolation of 37dB, with symmetrical waves pattern. The overall height of the aerial is λ0/4 and the design is simple and easy to fabricate. Thus, this new design is an ideal candidate for the new 5G BTS Applications.

ABSTRACT. This paper presents a technique of gain enhancement using stacked dielectric slabs atop a microstrip patch antenna for 28-GHz application. A microstrip patch antenna (MPA) is designed at 28-GHz and loaded with eight 15×15mm^2 dielectric slabs supported by seven 10×10mm^2 dielectric slabs in the center. This arrangement of dielectric slabs enhances the gain of MPA by 4.1 dB when loaded very close to the antenna without affecting its input reflection coefficient. The prototype antenna is tested for radiation performance and its observed that the measured and simulated results are in good agreement.

ABSTRACT. In this paper, circularly polarized substrate integrated waveguide (SIW) planar inverted-F antenna (PIFA) with slots in T-shape is presented. The main focus of this work is to achieve polarization diversity. The basic proposed PIFA antenna is linearly polarized with low gain. In order to obtain a low profile, compactness, high gain, the planar inverted-F antenna is integrated with SIW. The gain of the antenna is increased by inserting inductive metallic posts with different orientation into the substrate of the PIFA antenna. The transformation of linear polarization to circular polarization is done by deploying slots in T-shape on the upper surface of the substrate in a specific pattern. The dimension of the repeated slots is 0.02λ0  0.02λ0. The vertical shorting plate of the antenna acts as a dipole whose length is less than λ0/10. Besides that, a shorting plate is used to balance the polarization as well as maintained the bandwidth. The proposed antenna shows good performance over the frequency range for 5G applications.

ABSTRACT. A Wideband Dual Frequency CPW feed rectangular patch antenna has been designed for the C, X and Ku band applications with an operating frequency range of 3.9GHz to 7.2GHz covering 3.3GHz of bandwidth and 11.2GHz to 13.1GHz covering 1.9GHz of bandwidth. Patch has been etched with slots in a periodic manner which led for the generation of dual wideband bandwidths. Flame Retardant Glass epoxy is taken as substrate material which is having a thickness of 1.6mm and a 50Ω stripline has been used to excite the antenna. Fractal technique has been implemented to attain the wide bandwidth of operation. The overall dimension of the antenna is 27.4mm×20.8mm×1.6mm. The Proposed antenna is having wide bandwidths covering the C, X and Ku band frequencies ranging 3.9GHz to 7.2GHz covering 3.3GHz of bandwidth and 11.2GHz to 13.1GHz covering 1.9GHz of bandwidth with a return loss value less than -10dB for entire bandwidth. Commercially available 3D simulator Ansys HFSS software has been used to design the proposed antenna.

ABSTRACT. The proposed talk will explore the story about how the emergence of a new technology known as gap waveguide technology has happened and why the speaker has been involved in its development. The technology is useful for designing antennas and components in the millimetre frequency bands and it is based on simple principles but it has lot of potential. Along the talk, the female perspective of being a researcher in the antenna world, based on personal experience, will also be covered.

ABSTRACT. Performance characteristics of wireless communication system can be readily enhanced through the development of reconfigurable antennas. Current wireless communication systems have ability to achieve multifunctional capabilities with a single system supporting several applications with different operating conditions. However, as each application operates in different frequency bands, with different radiation pattern or different polarization, such a single system requires multiple antennas. This is because historically from systems stand point, antenna has been viewed as a static device. Once an antenna design is finalized, its operational characteristics remain unchanged. This has driven innovation in antenna towards multifunction capabilities in competence with the contemporary communication systems. Reconfigurable antenna is a remarkable technology that adds novel features to existing conventional antennas whose characteristics are fixed and remain unchanged. The proposed talk will explore emerging area of reconfigurable antennas from basic concepts that provide insight into theoretical foundation, fundamental design approaches and practical considerations of various reconfigurable antennas in modern wireless communication systems.

ABSTRACT. One of the key sub-system of any radar is the “Antenna”. With the advancements in the radar technology from the conventional passive antenna radar, passive phased array, active phased array and the digital active array, the antennas catering to each radar technology has led to tremendous amount of research and development activities in the field of antenna. No single type of antenna can be considered to meet the requirement for all the radar. Conventional antennas like the parabolic reflector fed by horn, microstrip patch and slotted antenna array are still being considered for radar. Most of the phased array radars have microstrip patch as the array element. In an active phased array, the mutual coupling between the anten na elements plays an important role in the overall performance of the array. Unlike in a conventional antenna, return loss of the antenna suffices, in an active phased array, a designer is concerned in the active return loss of the antenna over the scan angles. Over the last decade most of the radars have been designed in the L, S, C, X and Ku bandfrequency range. But due to certain advantages of using the lower frequency spectrum, HF, VHF and UHF radar design in the country are being taken up. The challenge for the antenna designer in the lower frequency spectrum is enormous as the antenna dimensions are large owing to the frequency whereas the program would be envisaging a low-profile antenna.Even though antennas are one among the well-researched area with lot of open literature available to access, the field of antenna still offers a vast area for research, as it is left to the imagination of the researcher and the physics of radiation that encourage researchers to explore new radiating element to design it to radiate to meet the requirements.

ABSTRACT. Antenna performance is very crucial for all satellites to satisfy the mission requirements. The characterization of antenna performance on ground confirms the conformance to the d esign specification. It is essential to characterize the antennas for radiation pattern, absolute polarization, gain and XPD measurements at subsystem level and at S/C level on ground, to get confidence that during the in-orbit operation of the satellite these antennas will work as per desired specifications. URSC-CATF has rich experience of carrying out tests both at antenna level and S/C level, covering frequencies from L-band to Ka-band.The talkgives an overview of satellite antennas, a brief introduction to compact antenna test facility (CATF)and its capabilities and Antenna and satellite level RF characterization in CATF. The presentation also discusses the case studies pertaining to RF integrity issues observed during some of the test campaigns like polarization reversal, effect of spacecraft body on antenna patterns etc., which otherwise would have affected on-orbit performance.

ABSTRACT. Cardiovascular disease is the leading cause of death in all developing countries. More than 50% of death in the rural area is caused only by heart diseases. A deep-down study reveals alarming reasons like financial constraints, high population growth, lack of specialist doctor, unawareness about the current health status and poor infrastructure of the hospital.To address this, numerous engineering approaches are proposed in the literature but very few of them are sustainable due to complex nature of the system. Computed Tomography (CT) scan, X-ray, Electrocardiogram (ECG) are still unreachable to the rural society. Mass scale cost-effective minimum infrastructure-based approachwith an inbuilt detection capability of Heart Sound Signal (HSS) can save many lives.In this lecture, an HSS-based diagnosis systemapplicable to rural health care would be discussed. The system presents heart sound listening, onboard data storing, simple user interface, real-time visualization, Wi-Fi connectivity for remote monitoring or IoT implementation and primary level investigation of HSS. De-noising is a crucial step for reliable and accurate identification of HSS components such as S1, S2, and others as HSS gets easily corrupted.A very simple and efficient Power Law Algorithm (PLA) to perform de-noising in time domain to suppress the low amplitude noise will also be discussed. Finally, HSS component identification and analysis for awareness generation would be delivered.

ABSTRACT. Recent advances in technology has led to the development of Internet of Things (IoT), Wearable Electronics, 5G Wireless Systems, etc, which requires widespread deployment of sensors positioned at remote places with the capacity of communicating wirelessly with each other. Power is often the limiting factor, as we have to depend on battery sources. This leads to the tedious task of disposing and replacing enormous number of batteries. RF energy harvesting (RFEH) presents a promising solution as RF power is a suitable choice particularly in cases where s olar harvesting is not feasible. However, in spite of RF communication system design being a well‐established, there are several challenges poised for the implementation of the RFEH systems especially when harvesting the ambient RF signals. The challenges can be widely categorized as the low/variable incident power, overall conversion efficiency, bandwidth, load variance and form factor. In this presentation, important design issues are identified with insights drawn. First, the challenges in designing antennas for RFEH systems will be discussed followed by rectifier circuits and matching networks, and eventually a general frame work for designing of ambient RFEH systems will be deduced.

ABSTRACT. RF communication systems are integral part of satellite launch vehicles. The telemetry, tracking and commanding (TTC) functionalities are met by dedicated onboard packages with the support of compatible Ground Stations, operating at specific frequency bands. Important parameters to assess the health of the launch vehicles, captured by sensors, are down-linked by Telemetry Transmitter. Accurate vehicle tracking for ranging is done by Radar with the support of onboard Transponder. The vehicle is equipped with Receiver to accept and process any uplinked commands, if found essential. The position and velocity information, derived from GPS-NavIC system is used to aid vehicle navigation. In this presentation, the different RF systems used in launch vehicles will be projected. The requirement, functionalities, configuration and implementation schemes will be highlighted. Finally, the emerging trends in RF systems to cater to the demands of new generation launch vehicles will be touched upon.

ABSTRACT. In this paper, a dual-band Minkowski fractal bandpass filter for GSM applications is presented. The Minkowski fractal concept is considered for inter-digital structure to suppress the unwanted bands as well as, to produce Transmission Zeros (TZs) to enhance the filter performance. The proposed filter is simulated using Ansys-HFSS EM Solver and fabricated on FR4-Epoxy glass having an overall size of 41.5 X 32.8 mm2. The first band operates at center frequency of 900 MHz and second band operates at center frequency of 1800 MHz. Suitable transmission zeros are produced to isolate the two bands and suppresses the creation of spurious bands. The measured results of S (1, 1) and S (2, 1) are presented and they are promising at par with the simulation results.

ABSTRACT. A Compact miniaturized asymmetric fed Moore curve with fractal, DGS and SRR are designed for several wireless applications. The compact size of proposed antenna is 25mm x 25mm x 1.6mm. By the proper alignment of fractal shapes, this Moore curve obtains multiple resonances. To improve the several performance characteristic of proposed antenna like bandwidth, gain and radiation efficiency, defected ground structure (DGS) and split ring resonator (SRR) are loaded. The maximum peak gains at the center frequencies are 2.67dB at 2.32GHz, 2.82dB at 4.84GHz, 3.60dB at 5.14GHz, 2.62dB at 5.58GHz, 3.41dB at 6.66GHz, 1.87dB at 7.22GHz, 2.37dB at 7.66GHz, 1.11dB at 8.36GHz and 2.41dB at 9.78GHz.

ABSTRACT. This paper presents design of broadband circularly polarised 4x1 helical antenna array in L-band to achieve unequal beam coverage in two planes. The 4x1 corporate feed network is designed using Wilkinson power divider to feed four helical antennas in equal amplitude and phase to achieve beam coverage along axial axis. The antenna array is covered with fiber glass radome to protect from environment. The 4x1 helical antenna array has maximum gain of 14.7 dBic, half power beamwidths of 19 degree in azimuth plane and 47 degree in elevation plane at the center frequency.

ABSTRACT. A novel Decagonal Sierpinski Fractal antenna having a modified ground and asymmetric co-planar feed line for Ultra-wideband (UWB) applications has been proposed in this paper. The simulation results of proposed antenna display its capability of operating over ultra-wide range, ranging from 3.31 GHz to 31.11 GHz (i.e. bandwidth of 27.8 GHz is obtained) and peak gain of 8.06dB. Proposed antenna design has shown optimal gain characteristics and stable radiation patterns. Proposed antenna finds usage in military applications, satellite communication, sensor networks and habitat management etc.

ABSTRACT. In this article, the design of a Pythagorean-tree shaped fractal microstrip antenna is investigated for RFID reader applications. The antenna consists of a fourth-order Pythagoreantree shaped fractal, a feed-line matched to the radiator, and co-planar waveguide (CPW) line with the filleted ground plane. The monopole antenna provides a wider operational bandwidth from 4.22−7.52 GHz. The use of fractal geometry enhances the bandwidth of the microstrip antenna and reduces the metallic footprint size to a great extent. The simulated reflection coefficients are also validated with measured results. The simulated radiation characteristics demonstrate an omnidirectional pattern with the realized gain of 2.9 dBi at 5.8 GHz. The antenna with an overall dimension of 0.36λ×0.43λ×0.015λ (λ represents the wavelength at 5.8 GHz) covers the entire 5.8 GHz ISM band.

ABSTRACT. The design of wearable fractal antenna on the spiral shaped MTM substrate suitable for MBAN (2.36-2.4GHz) and ISM (2.4-2.45GHz) frequency bands is presented in this paper. This antenna is composed of a fractal outlined square patch as the main radiating element on the FR4 substrate of size 36 mm×36 mm×1.6 mm. A spiral shaped MTM structure is included in the ground plane of the antenna to attain the resonance at the design frequency and appreciable gain. The proposed wearable antenna may be attached to human body, so the specific absorption ratio (SAR) must be as per the standards. Another design to reduce SAR value with a spiral metamaterial superstrate operating at the desired frequency band is introduced. It is inferred that the superstrate is capable of reducing SAR by 29.12% and 60.18% at 2.36GHz and 2.4GHz respectively with promising antenna performances.

ABSTRACT. Microstrip patch antennas possess low bandwidth and gain. In order to improve the performance parameters in these antennas, many structures like Electromagnetic Bandgap Structures (EBG), Defective Ground Structures (DGS) and Metamaterials (MTMs) are proposed. This paper presents a ultra wideband, dual polarized and highly efficient dual feed dumb-bell shaped patch antenna. The proposed patch is mounted on the splattered ring Electromagnetic Bandgap (EBG) structure. Overall dimensions of the patch are 25 x 30 x 1.524mm3. The proposed antenna is possesses an axial ratio of 2.1dB at 11.78GHz and axial ratio higher than 4dB in the remaining band. The proposed antenna is possesses bandwidth of 20.2GHz (171.4%) with the gain varying from 6.21dB to 9.03dB in frequency range of 10.8GHz-31GHz. This further possesses efficiencies varying from 88.34% to 91.06% in the said frequency range. The whole structure is designed using CST Microwave studio 2016.

ABSTRACT. : In this work, a compact CPW (Coplanar Waveguide) fed square slot antenna with grounded L-strip and I-shaped radiator for wideband circular polarization is designed, analyzed and fabricated. Proposed antenna provide left hand circular polarization (LHCP) which are described by surface current distribution. It is simple in structure and provide ultra-wide band impedance bandwidth (IMBW) 116% and wideband circular polarization (3-dB ARBW) 33.96%. The peak gain and efficiency of this simple structure are 5.92dBi and 91% respectively. The overall floor surface area of proposed antenna is 20×20×1.524 mm3.

ABSTRACT. In this paper, printed IFA is presented having coplanar waveguide feed with Ultra Wide Bandwidth (UWB). The dimension of antenna is 14mm × 24mm × 1.59mm. The IFA structure has a printed inverted L-shaped stub on the left hand side of the ground plane with a spiral shaped defect on the right side of the ground plane. The simulated bandwidth is defined from 3.0 GHz to 11 GHz with reflection coefficient -10dB. The compact size and also the printed structure of antenna make it more useful for practical applications. The antenna is fabricated over FR4 substrate having relative permittivity εr =4.4 & thickness h=1.59mm. The simulated and measured results are well matched.

ABSTRACT. In this paper a small Circular Edge Cut Monopole UWB Antenna for Wireless Communications is presented. The proposed antenna has the dimensions of 30×35 mm2 and provides the UWB Bandwidth from 3.1 to 10.6 GHz. This wide B.W is achieved by partial grounding technique with circular disc, a modified center slit at center of ground plane and the circular shaped cuts at the corners of the patch. The antenna is fed by microstrip transmission line with impedance matching achieved by a stub. The antenna also has a low level of cross polarization and better efficiency throughout the entire UWB range. This confirms the usefulness of this antenna for UWB applications and wireless applications.

ABSTRACT. A miniaturized planar antenna with partial ground plane for ultra-wide band application is presented. The structure with small in size 20*25*1.6 mm3 is etched out on low-cost (FR4) flame retardant substrate with εr=4.4 and 0.025 dielectric loss. The fractional bandwidth (S11) of the structure is 155 % (2.50-20 GHz). Gain of the structure is 6.1dB and the antenna efficiency is 83% respectively. Structure radiated Omni-directional and Bi-directional radiation pattern. Simulated and measured results of Co-pole. and Cross(X)-pol. are in relatively good agreement. All these properties show that, the proposed structure finds its applications in WiMAX-band 3.5, 5.5GHz, WLAN-band 5.2, 5.8GHz, X-band 8-12GHz, which is used for satellite communication and wireless communication.

ABSTRACT. This paper describes optimum antenna array structure for beamforming in smart antenna technology. Different examples of Array structures are analyzed by the use of newly developed optimization technique called Whale Optimization Algorithm (WOA). The design objective here has been considered to get the most favourable radiation patterns with sidelobe level (SLL) reduction by optimizing amplitude excitations, inter element spacings and phases of each elements of an array. The numerical and simulation results are compared with that obtained by most popular optimization technique, Particle Swarm Optimization (PSO), Cat Swarm Optimization (CSO) and Ant Lion Optimization (ALO) by building codes using MATLAB. The results show that WOA can exhibit relatively better performance than other algorithms for the antenna array synthesis examples and beamforming applications.

ABSTRACT. In this paper, a systematic procedure to reduce mutual coupling between linear 21 array microstrip antennas is proposed. The proposed design procedure is based on pixelization of the surface between two patch elements and application of a binary particle swarm optimization (BPSO) algorithm. In the binary optimization algorithm, each pixel is represented by a bit which gets a binary value of 1 or 0 indicating the presence or absence of copper on the area of the pixel. The optimization goal is set to minimizing the mutual coupling between two elements while the impedance matching and radiation pattern are not degraded. Full-wave simulation results are provided.

ABSTRACT. An approach for beam forming arrays with radiated electric fields that are solutions to second order linear differential (SOD) equations and higher even ordered differential (HEOD) equations has been developed. The fields represented by the solutions of these two types of generalizations propagate without diffraction within a specific range, self-accelerate, and result in asymmetric side lobes. In both the cases, the nondiffracting beams are generated over an appreciable range of a few thousand wavelengths, which translates to hundreds of meters at mm-wave frequencies. Based on the new mathematical approach presented here, near field nondiffracting and far field beam forming arrays are produced using aperture excitations that belong to a family of odd functions characterized by odd (cubic, quantic, heptic, etc.) inverse reflection symmetry phase distribution followed by Fourier lenses. These arrays perform more efficiently than conventional phased arrays with better than power attenuation in the nondiffracting range. The mainlobe and the dominant sidelobes are contained in one quadrant of the azimuthal plane, whereas the sidelobes in the remaining three quadrants are reduced significantly (by 9 dB at least, for the considered array size).

ABSTRACT. A coplanar waveguide fed eight-shaped pattern reconfigurable antenna is proposed. The antenna is operated between the frequency range of 2.61-3.44 GHz. The antenna is capable of switching its pattern from Omnidirectional to directional with two different switching conditions of the PIN diodes. An omnidirectional pattern is achieved when both diodes are in OFF states whereas directional patterns are achieved when any one of the diodes is in ON state and another is in OFF state. The simulated and measured results are in close agreement.

ABSTRACT. The mechanism of reconfiguration is important to enhance the performance of an antenna as it can switch between different frequencies in a dynamic environment. In this paper, we propose a single layer microstrip rectangular patch antenna with parallel slots to obtain two resonant frequencies. The feature of reconfigurability is attained by using PIN diode switch. The simulated antenna performs switching either in the 2.4GHz or 3.7GHz by operating PIN diode in the on or off state in the particular slot. A parametric simulation is carried out to position the slots and switches which optimize a return loss less than -10dB, voltage standing wave ratio ≤ 2 and a gain greater than 2dB. The proposed design provides better gain with reconfigurable feature.

ABSTRACT. The design and optimization of dual mode five-way square waveguide power divider for multi-beam antenna (MBA) in Ext-C band is presented in this paper. The performance of the power divider with a well balanced power level for TE10 and TE01 modes are obtained over the frequency range 4.5GHz-4.8GHz. This type of power divider has a promising interest in the design of beam forming network of multi beam antenna

ABSTRACT. A circularly polarized antenna system is proposed for AMSAT-APRS digipeater which transmits and receives payload data at VHF band. This antenna system consists of asymmetrically placed four linearly polarized inverted F antennas which are supported by power divider and phase matched RF cables. These antennas are flush mounted along the circumference of stage 4 of PSLV at 0deg, 70deg, 180deg, 290deg planes. It provides omni-coverage with minimum gain of -10dBi and return loss better than 15dB.

ABSTRACT. Design of an electrically smaller diameter reflector antenna (diameter < 50λo) is a challenging task because the overall reflector efficiency is reduced by the higher percentage blockage due to sub-reflector, its support structure and the feed system. Further the reflector has to be mounted on a mechanically steered platform and support dual circular polarized operation on a satellite. These requirements added further to the design complexity. This work provides a good working design of a 0.35m diameter reflector antenna in Axially Displaced Ellipse (ADE) geometry and its feed at Ka-Band for transmitting high throughput payload data to the ground stations. Realized efficiency is more than 50% with cross-polar isolation better than 30dB.

ABSTRACT. In this paper, a compact planar Printed Quasi-Yagi Antenna is proposed for wideband applications. The proposed antenna consists of driven half bow-tie monopole element, two director strips and finite ground plane. The main feature of the designed antenna is its compact size and which is obtained by modifying the driven element as a half bow-tie shaped monopole and reflector’s shape. To feed the driven half bow-tie monopole element, a linearly tapered microstrip line is implemented which helps to improve the impedance matching over the operating bandwidth. Initially, the proposed design concept has been optimized using CST Microwave studio and obtained results are compared with experimental ones. The measured results show that the antenna has |S11| < -10 from 1.62 to 3.12 GHz (63.54 %) with measured peak gain of 5.8 dBi. The proposed antenna has a stable end-fire radiation pattern with cross-polarization level and front to back ratio better than -25 dB and ∼10 dB respectively. The simulated and measured results are in good agreement. The proposed design is simple in structure with on chip area of 0.41 × 0.41 lamda02 (lamda0 is free space wavelength at center frequency of 2.31 GHz).

ABSTRACT. Most of the airborne fire control radars (FCR) are migrating to the modern active electronically steered array (AESA) technology from mechanically scanned array (MSA) technology. The FCR radars are normally installed in the nose of the aircraft that acts as a radome. Apart from structural characteristics, the Electromagnetic characteristics of the radome are essential for the performance of the radar. It leads to the antenna principal beam attenuation, deflection and reflection. The design of radome for AESA radar for airborne applications is a major challenge due to its shape and size requirements. Very few pioneers in the world are developing this class of radomes. Manufacturing of these radome as per the design is another big challenge. Then it comes to the Electromagnetic (EM) characterization of the radome, for radar application this is an elaborate process as they are to be carried out are very high in number. The advantage of desired beam formation in AESA radar brings more complexity as the radiation patterns are different in transmission and reception. This paper presents the issues in design and development of low loss, high performance radomes for airborne AESA radars on fighter aircrafts. Also it focuses on the radome effects on AESA antenna main beam attenuation and side lobe level degradation in Transmission and reception. The simulation and analysis of this kind of radomes is presented and discussed.

ABSTRACT. This paper presents studies on the design and development of conformal antennas placed on cylindrical curved surfaces. A planar 96x8 element conformal antenna array has been designed and a section of the array with 24 elements has been studied in terms of gain, beamwidth and Sidelobe level. The design has been carried out using MATLAB and the optimization has been carried out using 3D EM simulation software HFSS. The conformal array have been fabricated on RT Duroid substrate of thickness 20 mil and the measured results are presented.

ABSTRACT. Present paper discusses the realization of 4x4 Ku-Band radiating array for airborne line of sight (LOS) communication system. The antenna uses microstrip stacked configuration to achieve wide band operation from 14.4 GHz to 15.5 GHz i.e. (bandwidth greater than 7%). The proposed antenna has been printed on Roggers RT duroid 5880 substrate and it uses corporate feeding techniques. The designed antenna has been modeled, simulated and optimized on ANSYS HFSS full wave EM simulation software. Measured VSWR of the developed antenna is 2:1 over 14.4 GHz – 15.5 GHz. Measured radiation characteristics of the developed antenna show excellent agreement with the simulated values. The measured gain of the realized 4x4 microstrip array antenna @ 15 GHz is 17.9 dBi. The antenna along with dual axis positioning system can be fitted at the belly of UAV for high data rate LOS communication with ground station.

ABSTRACT. The deterioration in highest side lobe level (HSLL) due to quantized control of phase shifters in analog phased arrays is investigated. The finite resolution limits the HSLL that can be achieved. An algorithm based on ordered binary decision diagram (OBDD) is proposed to compensate for HSLL deterioration which is found to be suitable for moderately sized arrays. The proposed algorithm provides maximum improvement of about 8 to 10 dB, depending upon the ideal value pf HSLL, scan direction and the number of antennas.

ABSTRACT. This paper presents closed form analytical expression of directivity for arbitrary planar array antennas. The expression is used to study and compare the directive characteristics of dense arrays and sparse arrays. The study encompasses two popular array arrangements, viz, square and concentric ring arrays. As an outcome of the study superiority of sparse arrays over dense arrays in terms of wide scanning performance is established.

ABSTRACT. This paper presents analysis of dual-offset Gregorian antennas with varying subreflector angles. Compatible feed designs are shown. Simulated antenna patterns, aperture efficiency and off-axis performance are compared.

ABSTRACT. Communications antennas for space, air, and ground applications often use phased arrays and reflector antennas. This paper provides design equations and guidelines useful for engineering professionals for quick and reasonably accurate design of these antennas without resorting to time-consuming simulations. Insight of various design parameters and their impact on the RF performance is given.

ABSTRACT. Null steering or null creation in a desired direction is of interest in various long-range communication applications. It requires the calculation of optimized complex weightings for the entire array to steer the main beam in the direction of the desired signal and create nulls in the direction of noise signals. These weightings can be calculated easily by considering imaginary narrow beam pattern rather than actual elemental pattern as basis function for the calculation of the array pattern where the weightings of narrow spot beams and the elemental beams are discrete Fourier transform (DFT) pairs. In this paper a DFT based synthesis technique to generate broad nulls in desired direction in rectangular phased array antennas is presented.