ABSTRACT. In this paper, a compact and wideband square-slot circularly polarized antenna is proposed. The proposed antenna based on microstrip line fed inverted L-shaped radiator and modified ground plane. The ground plane is modified by incorporating an inverted L-shaped grounded strip and etched a rectangular portion from the lower right corner. Therefore, a wideband circular polarization(CP) coverage is obtained within a compact size. The magnitude and phase differences between the two field components (EX, EY) can be controlled effectively by properly tuning the dimensions of the horizontal section of the inverted-L shaped radiator. Which is helpful to minimize the axial ratio (AR) values (≤3dB) to widening the ARBW over the C-band. The overall dimensions of the prototype is only 22×22×1.6 mm3. The simulated impedance bandwidth (IBW) is 17.86% (5.15-6.16GHz) and a 3-dB AR bandwidth is 24.61% (5.06-6.48GHz). A peak gain of 3.8dB is achieved within the ARBW. The proposed antenna is suitable for circular polarization applications in C band.

ABSTRACT. This paper presents a compact dual feed Circular Microstrip Patch antenna [ 39 X 39 X 07mm³] for various SATCOM(Handheld) Terminal for MSS Application. Circular patch antenna is printed on multilayer bare PCB material (High dielectric constant εr: 10.0) in stacked configuration. The Right Hand Circularly Polarization has been achieved by using dual feed (two orthogonal modes) lateral excited by Wilkinson Power divider (fabricated on Low dielectric constant substrate) beneath the separate ground plane. All bare PCB of same thickness is stacked up with Cynatyster adhesive of having same dielectric constant and thickness. At the bottom side of ground plane, Wilkinson power divider layer printed on separate substrate (low dielectric constant) is backed by Rohacell foam, so that Antenna could be safely placed at the desired location in Terminal. Because of Stacked substrates, net effective dielectric constant becomes less along with high thickness, which enlarges the percentage Bandwidth of the antenna. Simulated Gain of the Antenna is better than 2.5 dB up to (± 45°) over the desired frequency band (2.56 – 2.69 GHz.), while Axial ratio is less than 0.3 dB in the range (θ ± 45°) in the entire band. Antenna is having wide return loss bandwidth (better than 20 dB in the desired Band, while -17dB return loss Bandwidth is around 21%. The antenna was characterized with MSS handheld terminal (Broadcast Receiver as well as Reporting Terminal) itself and met all performance requirements.

ABSTRACT. A multiband planar antenna is presented for cellular and wireless communications. The presented antenna realizes an overall size of 40$\times$40$\times$1.6 mm$^\text{3}$. It consists of a G-shaped and inverted L-shaped radiator. The G-shaped radiator is responsible to offer 1800 MHz, 2.45 GHz, and 3.5 GHz frequency bands, while the inverted L-shaped radiator is able to provide resonance at 900 MHz and 5 GHz frequency bands. Moreover, the proposed multiband antenna offers good radiation characteristics and gain for desired frequency bands. In addition, the proposed antenna design is fabricated and measured to validate the simulation results.

ABSTRACT. A miniaturized wideband Vivaldi antenna is presented in this paper. The proposed antenna is compact in size, has wide bandwidth and high radiation efficiency. The antenna is designed on FR-4 substrate with overall dimensions of $20\times17$ $mm^2$. The resonating frequency of the reported design is observed as 5.8GHz and impedance bandwidth is 2.67GHz (4.94GHz - 7.61GHz). The simulated radiation efficiency and gain are approximately 98.9\% and 3.66dBi, respectively. The proposed design finds its applications in IoT, 5G, Wireless LAN (WLAN), Intelligent Transportation System (ITS) and Radio Frequency IDentification (RFID).

ABSTRACT. This paper demonstrates simple, low-cost and high gain microstrip antenna with suitable feeding technique and dielectric substrate for application in 28 GHz frequency range. We designed and analyzed a dual band 3D printed rectangular microstrip patch antenna for 28GHz and 38GHz communications. The design concept is to have slots etched out from the copper patch of a microstrip patch antenna designed for 28GHz operation to enable second frequency band i.e. 38GHz operation. The proposed antenna provides impedance bandwidth of 6% (28.35 to 29.9) and 5.3% (36.89 to 39). The gains in the E-plane are 5.126dB and 5.011dB at 28GHz and 38GHz respectively

ABSTRACT. A novel, compact and ultra-thin monopole antenna for wireless operations in the Next-Generation laptop computer is developed. The thickness of the antenna is only 0.2mm and is designed using only a pure copper strip of size 20 ×6〖mm〗^2. The simple structure of the proposed antenna consists of two monopole radiating strips namely PS and ST and an open ended rectangular tuning stub QR of length 9mm. This structure generates two resonating modes at 3.45GHz and 5.5GHz and achieves the measured -10dB impedance bandwidth as 19.71% (3.20-3.90)GHz in lower band (F_l) and 16.17% (5.00-5.88)GHz in the upper band (F_u). The measured radiation performance including, nearly omnidirectional radiation patterns, a stable gain of around 5.2dBi and excellent efficiency around 86-92% in both operating bands have been achieved. Furthermore, the simulated and measured results are in good agreement which demonstrates the applicability of the antenna structure for WiMAX/WLAN operations in the prominent ultra-thin Next-Generation laptop computers.

ABSTRACT. A compact Vivaldi antenna for wireless mobile terminals is proposed. Proposed antenna is wide-band operating from 25-40 GHz with fractional bandwidth of 46%. Proposed antenna bears small physical footprint with dimensions of 6.2 × 9 mm2 thence can be easily accommodated along the edge of typical smartphone. End-fire gain of 5-6 dBi of the low profile Vivaldi antenna is achieved in the whole operating band. Stable radiation patterns with high pattern integrity are obtained. The 1-dB gain bandwidth of the proposed antenna is 46% with gain varying between 5-6 dBi over the whole operating band. Proposed antenna is accommodated along the edge of the typical smartphone with dimensions of 65 × 140 × 7 mm3. Proposed Vivaldi antenna uses dielectric load of smartphone case modeled as Teflon substrate thereby enhancing the peak gain to 14.5 dBi. Integration of proposed low profile Vivaldi antenna in a typical mobile terminal is demonstrated.

ABSTRACT. In this paper, an endfire circularly polarized and a broadside linearly polarized MIMO antenna system, with pattern and polarization diversity, is proposed. This MIMO antenna system consists of two endfire circularly polarized antenna, and a CPW fed linearly polarized antenna. The endfire circular polarization is generated by using two orthogonal elements as a magnetic dipole and electric dipole having 90 degrees phase shift. The broadside linear polarization is generated by CPW fed monopole antenna. The circularly polarized antenna and linearly polarized antenna give simulated return loss bandwidth as 1.1 % and 18 % respectively. The axial ratio bandwidth of the CP antenna is 4.8 %. The proposed structure is fabricated, and its antenna parameters are measured, which are well-matched with the simulated one. Along with basic antenna parameters, to characterize the MIMO antenna system, some additional parameters are also analyzed. The envelope correlation coefficient, mean effective gain, total active reflection coefficient, and channel capacity loss are within the desired range. The overall dimension of this proposed antenna is 1:2λ0 × 0:55λ0 × 0:018λ0, where λ0 is free-space wavelength corresponding to 3.5 GHz

ABSTRACT. The purpose of this paper is to design an antenna that operates at a lower frequency of 500MHz and has a small size suitable for space exploration rovers equipped with Ground Penetrating Radar (GPR). This antenna can be used for subsurface investigations of celestial bodies like Moon and Mars. The primary difficulty that lies within designing an antenna for lower operating frequency is its bulky size. To overcome this problem a structural investigation on the design of small size Vivaldi antenna at 500MHz for GPR applications is proposed. The antenna has been designed, optimized and simulated in the HFSS and fabricated on an FR-4 substrate of dimensions 65mm×60mm×1.6mm. The proposed antenna attains a lower return loss of 32dB at the center frequency 500MHz. In this paper, on a conventional Vivaldi antenna a horizontal bar type structure folded with increasing step size and a circular patch in the active plane has been introduced. Furthermore, optimization is carried out to achieve the desired results. Hence, the optimized Vivaldi antenna is presented for use in GPR applications.

ABSTRACT. In this paper, a compact QSC UWB-MIMO antenna using shared radiator is presented. The proposed design consists of a radiator which is centrally aligned at an angle of 45° from X-axis. It is symmetrically shared by two microstrip feed lines that results in orthogonal polarization. This made the design more compact as it does not utilize separate feeds for each port. At the bottom side of the substrate, quasi-self complementary structure is used to control the impedance of radiator. Also, an end loaded meandered line attached to the ground offers better isolation. The overall size of the designed antenna is 40 × 40 × 0.8 mm³.The simulated results satisfies the desired reflection coefficients requirement i.e. S₁₁/S₂₂ less than or equal to −10 dB and provides mutual coupling of S₂₁/S₁₂ less than or equal to −13 dB over the entire FCC allocated band i.e. 3.1-10.6 GHz. Moreover, all the simulated diversity parameters found suitable for UWB-MIMO applications.

ABSTRACT. In the presented manuscript, a compact antenna designed on Rogers RTDuroid 5880 substrate is presented which covers superwide bandwidth of 3.21GHz-19.43GHz. On one face of substrate, square monopole patches are printed and common ground on other side. Designed antenna is converted to dual notched band characteristics which mitigates Wireless Local Area Network (WLAN: 5.150GHz-5.825GHz) and Downlink Satellite System (DSS: 7.25GHz-7.75GHz) interference. These two notched bands are obtained by using inverted T-shaped stub and rotated C-shaped slot on radiating patch. Designed antenna has maximum gain of 5.33dbi and radiation efficiency of 86%. Far Field Radiation pattern shows omnidirectional and dipole like pattern in H- and E-plane. Diversity performance of MIMO antenna is also studied in terms of ECC (Envelope Correlation Coefficient), DG (Directive Gain) and TARC (Total Active Reflection Coefficient).

ABSTRACT. In this paper, we demonstrate the potential of IDM-CGF (infinitesimal dipole modelling-cross-correlation Green's function) method in estimating the spatial correlation matrix for dual-polarized massive MIMO systems. A uniform rectangular array (URA) of 100 interleaved infinitesimal dipoles (IDs) with horizontal and vertical polarization is considered as test case, and its dominant Eigen-space is determined for different angular spreads and cross-polarization discrimination factors, considering a wide-range of azimuth angles for incoming signals. Furthermore, we deploy the Karhunen-Loeve method to realize correlated Rayleigh fading channel vectors, which sheds some light into the performance difference of interleaved dual-polarized massive MIMO arrays, as compared to the ideal systems involving polarization-less isotropic radiators.

ABSTRACT. A printed dipole wideband Quasi-Yagi antenna for next generation 5G wireless communication networks is presented in the paper. The antenna is fed by folded micro-strip line with an etched slot in the ground plane. The feed network employed resulted in the wide-band impedance bandwidth of 24.3 - 39.5 GHz with the reflection coefficient of -10dB. The director elements having optimized size and spacing between them have resulted in the antenna gain of 6.5 - 8.2 dBi. The antenna is seem to exhibit a stable radiation pattern for the desired band. The proposed antenna has an overall compact physical size of 9*17mm2. In between the two dipole antennas, a ground strip of optimized size has been placed with 5.5mm spacing between the centers in order to obtain the better isolation with mutual coupling under -20dB for the whole band. The size and all other resulting parameters makes this antenna a desirable option for handheld communication devices for milli-meter wave 5G applications.

ABSTRACT. A flower-shaped wide-bandwidth dual-polarized antenna is developed for passive radar systems in this paper. The antenna is initially designed for covering the X and Ku bands (8 – 18 GHz). To improve impedance matching and enhance operating bandwidth, we introduce split-ring slots in radiating elements. Simulation and measurement results show that the antenna’s S11 is further reduced from - 10 dB to - 15 dB at the high operating frequencies while the fractional bandwidth is also increased from 91% to more than 114% with the presence of the split-ring slots.

ABSTRACT. The research work presents a broad band with good gain microstrip patch antenna. A rectangular slot is incorporated on the ground metallic plane. The dielectric constant and thickness of the PTFE substrate is 2.4 and 1.6 mm respectively. The proposed antenna is simulated using Ansoft designer software and investigations are done on different antenna properties like reflection coefficient, gain and radiation pattern. The proposed antenna offers large bandwidth of 110% (2.47 GHz to 8.52 GHz) with peak gain of 3.5 dBi (simulated) and 4.2 dBi (measured). The measured data are almost followed by the simulated one. It is specially designed for L – band, Bluetooth, S – band, WLAN and C – band applications.

ABSTRACT. In this paper a stacked microstrip antenna has been proposed, operating in GSM 900 band. The antenna is realized on two dielectric materials to examine its performance for wireless power harvesting applications. High gain of 9.03 dB & 10.5 dB at 900 MHz with more than 6 dB & 8 dB gain respectively over entire band is exhibited to receive maximum power for εr=4.4 and εr=2.55 respectively. Simulated and measured results are in good agreement with operational bandwidth of 145 MHz & 157 MHz respectively in both cases.

ABSTRACT. In this paper, the design and development of dual linearly polarized stacked patch antenna for GNSS Reflectometry (GNSS-R) application is presented. The stacked microstrip patch antenna with proximity coupled feed configuration is used in this design. This type of antenna can be used as a nadir looking antenna in the receiver of GNSS Reflectometry. The antenna has been developed and measured. The antenna is having measured 10 dB return loss bandwidth of 118 MHz (7.5%) and peak gain of 8 dBi at center frequency 1.575 GHz for both linear polarization. The antenna is also analyzed with the Zenith looking antenna and mutual coupling between these two antennas is better than 50 dB. This antenna is used for GNSS Reflectometry application.

ABSTRACT. A compact, as well as wideband design of a strip-fed microstrip patch antenna (MPA) is presented for X-band operations. A metal-ring superstrate is being used to load a conventional MPA for the enhancement of impedance bandwidth from 6% to 25%. More than 9 dBi peak-gain is revealed from a compact antenna (~l´l) over the wide operating band. Experimental validation is performed with a set of antenna prototype fabricated using the laboratory facility. Measured results are very close to the simulated predictions. Experimental data confirm about 29% matching bandwidth which is much improved compared to the simulated prediction.

ABSTRACT. This paper presents a two element tapered recessed ground microstrip patch antenna array at 60 GHz. The use of tapered recessed ground overcomes the fabrication challenges of narrow slots of inset-feed technique, especially on high indexed substrates. Prototypes of 60 GHz 2 × 1 conventional (A1) and tapered recessed ground (A2) microstrip patch antenna array are fabricated on 0.127 mm thick alumina substrate (εr = 9.8) as a proof of concept. The measured results indicate a -10-dB impedance bandwidth of 2.16 % (A1), and 14 % (A2) with return loss better than 15 dB at 60 GHz. The measured gain of antenna A2 (7.05 dBi) is more by 1.2 dB, than antenna A1 (5.85 dBi) at 60 GHz.

ABSTRACT. In this paper miniaturized Quad Band Monopole Microstrip Antenna for Deep Space Communication Applications is presented. The antenna has the dimensions of 30×36.7 mm2.The antenna is fed by microstrip transmission line. The VSWR is close to ideal value (i.e. unity) due to perfect impedance (Ω) matching of 50Ω for each band and minimum reflection coefficient in the range -40dB to -60dB for each desired band are obtained. Particular desired band is achieved with step by step combination of particular cut slot at the center of patch, feed line and defective ground. Proposed antenna gets better required bandwidth for radar and satellite communication. The proposed antenna works effectively in 8-12 GHz X-band, 12-18 GHz Ku-band and 18-26 GHz K-band which comes under the satellite communications and radar applications.

ABSTRACT. In the days of miniaturization, compact antennas which are conformal to the hosting surface are widely used. Due to various advantages, shorted microstrip antenna variation, a planar inverted F-antenna with modifications have been widely referred. In this paper detailed study into functioning of planar inverted shorted microstrip antenna employed with modified L-shape feed is presented. It has been shown here that wider bandwidth is result of optimum spacing of TM1/4,0 mode with reference to next higher order degenerated TM3/4,0 modes as well as optimization of impedance at them using the modified feed. A modified variation of similar configuration with increased feeding length is presented which yields impedance bandwidth of 7.3 GHz (>95%) which is 40% additional as compared with the reported design. Parametric design guidelines are presented for shorted modified antenna which will provide design methodology for realizing similar antenna at different frequency.

ABSTRACT. This paper presents the design and development of capacitive coupled, stacked microstrip patch antenna operating over full GNSS band (1.1 GHz to 1.7 GHz) with Right Hand Circular Polarization. Four probes with capacitive coupling and sequential rotation technique for improving the axial ratio < 2dB over the full band. Wideband 90-degree and 180-degree phase shifters are designed for broadband operation of the feed network. Measured return loss is > 10 dB over the band from 1.01 GHz to 1.75 GHz (53.6%). Measured and predicted radiation patterns show excellent match and good cross pol characteristics.

ABSTRACT. In this paper, a compact uniplanar microstrip antenna (MSA) for endfire radiation pattern is designed with simple feed, high gain and front to back ratio (F/B) at 2.46 GHz. The antenna size is reduced by meandering the driven element. It is fed by a simple unbalanced coaxial feed. Performance of the antenna is analyzed by varying the antenna dimensions. The fabricated antenna size is 0.38λo x 0.11λo. Experimental results are in agreement with simulated ones. It provides 5.5 dBi gain with F/B of 12.7 dBi at 2.46 GHz. The designed antenna can be easily integrated with printed circuit boards.

ABSTRACT. A Compact circularly polarized coaxially fed slotted microstrip patch with Defected Ground Structure (DGS) is proposed in this paper. DGS is introduced to increase the effective current path length and miniaturize the antenna. Microstrip patch size is reduced by 40% using the proposed DGS and slots. Two pairs of asymmetrical slots are etched parallel to the edge of microstrip patch and is coaxially fed along the diagonal to obtain circular polarization. An axial ratio of 0.4dB is achieved at L5 band (1.175GHz). Further a ring is cut around the feed to match the antenna input impedance. Proposed antenna of size 35mmx35mmx1.27mm is fabricated and 10dB return loss bandwidth of 8MHz is achieved. Design, development and results of the antenna are presented.

ABSTRACT. In this paper, a wideband shorted differentially fed patch antenna has been explored based on composite aperture concept. Two λg/4-folded s-band patches are placed on a compact ground plane which promises 200° wide symmetrical radiation patterns over the principal planes along with 50% operating bandwidth. 7 dBi peak gain has been recorded with more than 45 dB co-to-cross-polarized isolation spanning over 360° angular range.

ABSTRACT. Many science applications at submillimeter-wave and terahertz frequencies require extreme sensitivity and that is possible only with cryogenic sensors. Properly designed coherent cryogenic sensors are capable of achieving quantum noise limited sensitivity and incoherent sensors can even detect a single photon. In this talk, the basic guidelines for the design and development of cryogenic submillimeter-wave and terahertz sensors will be provided. Details of how these sensors can be integrated with antennas and other coupling structures will also be provided. Emphasis will be given to end-to-end system design of cryogenic receiver-based instruments.

ABSTRACT. Space Applications Centre of the Indian Space Research Organization (ISRO) has embarked upon an initiative to develop sub-millimeter-wave technology in a phased manner, approaching it from the microwave frequencies. The vision of this program is to bridge the terahertz (THz) gap that exists in India, between the technologies at microwave and infrared regimes of the electromagnetic spectrum. This paper will focus upon the first phase of the development at 230 and 345 GHz. Globally, astronomy has been the prime science driver for THz technology development although it has its applications in various other fields too, including remote sensing, military, medical and communications. The goal of ISRO’s terahertz program is to develop astronomical telescopes at progressively higher frequencies involving more complex and sensitive detection technologies and demonstrate them first on ground, and then in space. The telescope being developed in the first phase is planned to be installed atop Mt Saraswati at Hanle, Leh to map the Milky Way for CO transitions with J: 2→1 at 230 GHz and J: 3→2 at 345 GHz with 1’ angular resolution, which will be the first of its kind from northern hemisphere. Till date, the Harvard Smithsonian Centre for Astronomy survey of the galactic plane at 8’ resolution is the only comprehensive survey available for CO (1→0) line from the northern hemisphere. The simultaneous measurements of these transitions for 12CO and 13CO will make kinetic temperature, H2 number density and column densities accurately derivable for the clouds, essentially mapping the star-forming regions over the entire galaxy. Additionally, it provides the opportunity to join the network of Event Horizon Telescope and improve the angular resolution significantly. It is proposed to deploy the telescope on Mt. Saraswati, Hanle which is approximately at 4500m from mean sea level with less than 2mm precipitable water vapour across the seasons, allowing around 260 spectroscopic nights in a year. The major technological challenge is to achieve the sensitivity required for detecting those faint lines having intensities of the order of few Jansky/Ω. Sub-harmonically pumped Schottky Barrier Diode based double sideband mixers, cooled to 40K, will be developed at both the frequencies, which will achieve noise temperatures of the order of a few hundred Kelvins and sensitivity of 0.5K/arcmin. The elements of the receiver, the Radio Frequency (RF) Front-ends (mixer, IF amplifier and LO multiplier), Intermediate Frequency (IF) backend (power divider, sideband separating mixer, filters and amplifiers) and the Frequency Synthesizer chain will be mounted on vacuum sealed three-tier cartridges cooled to 40K, 100K and 300K respectively with a Gifford Mcmahon - Joule Thompson cryo-cooler. An alt–azimuth mounted 3m on–axis paraboloid–hyperboloid Cassegrain antenna is being developed, which is planned to be upgraded to 6m subsequently. The reflector will be a multi panel structure with 20−30µm surface rms and 2” pointing accuracy. The backup structure will be made of thermally stable material with low expansion coefficient allowing the use of telescope during daytime without any significant degradation in pointing accuracy. A sequence of beam-folding mirrors and reflectors will be placed in the focal plane to direct the incoming radiation to the feed horns (through RF-transparent windows) which are mounted atop the RF frontend within the vacuum-sealed cryostat. In order to resolve the CO line widths at ~1Km/s over a velocity spread of ~900Km/s, instantaneous bandwidth of 4 GHz is to be sampled and resolved at 1MHz resolution. The IF bandwidth of 4−9 GHz is further down-converted and band pass filtered before being fed to FFT based digital spectrometers. High speed ADCs (4Gsps) will be used for this purpose along with high throughput FPGAs (Virtex-5). The stream of CO line spectra generated by the digital spectrometer will be transmitted to a local computer, wherein it will be further processed and stored. Complete control of the telescope will be with the telescope controller, which will interact with every subsystem and issue timing and command signals. The scan mechanism of the telescope will be controlled via a scan controller.

ABSTRACT. Radio technology in any sp ecific wave band essentially involves the development of elements until the first down c onversion. Therefore, the development of direct detec tors , low noise amplifiers, filters, mixers and their lo cal osc illator sources all form bulk of the technology development. Antennas and feed elements to o are imp ortant as they also play a crucial role in the collection and de tection of terahertz waves. Whether one wishes • to image the shadow of a black hole, or • to study the cosmic background radiation to understand the details of how the universe came about, or • to know if we are alone and if there is life elsewhere, or • to find out how stars and planets formed and whether there are livable rocky planets like the Earth elsewhere, collecting and detecting terahertz waves is important because they carry unique information from these objects to us. India had made efforts to locally develop high frequency astronomy from early on when they were being pioneered and pursued in leading western nations. In this talk, first I will present our early efforts towards detecting millimetre waves for astronomy application, including deploying a tipper to assess a high altitude site in the Himalayas for its suitability for Terahertz astronomy. Next, I will present two antenna concepts ([1], [2]) suitable for economical construction of ground based terahertz antennas. There after, I will conclude by outlining current efforts to develop astronomical instruments to pursue ground based terahertz astronomy from India.

ABSTRACT. The paper presents an optimized design procedure of a hybrid feed horn for the reflector antennas in communication applications at S-band. All design parameter for hybrid feed horn was studied extensively in detail and a theoretical, as well as mathematical explanation for same, has been proposed. The design procedure presented is in a generalized form to have a basic fundamental starting and further, the designer can generate an algorithm of his own depending on the preferred application. The boundary conditions to a well-designed geometry surface allow TE and TM modes of corresponding order to propagate at the same velocity over a frequency in the hybrid form. Mode conversion is required to generate hybrid modes and design parameters for the variable depth slot, ring loaded depth slot, and variable pitch to width slot mode converter is presented here in detail. As an example, the design of a ring loaded slot depth mode converter following a linear profile is presented. The proposed work is focused on S-band application for its excellent radiation penetration. The Concern in S-band passive elements of size miniaturization has been addressed in the given example. The simulated results manifest low return loss and radiation patterns with good beam symmetry, gain, and low cross-polarization. 

ABSTRACT. This paper focuses on the designing of a compact, light weight, low-cost and low profile antenna for tri band wireless applications. A rectangular patch is modified with triangular cuts at mid portion of the extreme right, left, top and bottom sides of the patch to form a KOCH fractal antenna. This structure is analysed using CST studio suite 2017 software simulator which works based on finite difference techniques for time derivatives. The proposed antenna is fabricated on FR-4(flame retardant) substrate with $ 80.0*80.0*1.57 mm^3 $ and with permittivity of 4.4.Koch technique is proposed in this paper in order to design a tri-band micro strip antenna which resonates at 0.785 GHz, 1.985 GHz and 2.47 GHz. The CST simulated results show that when Koch fractal micro strip antenna is designed, the antenna operates with three frequency bands for return loss of -13.59 dBi, -23.73 dBi and -15.84 dBi at 0.785 GHz, 1.985 GHz and 2.47 GHz respectively.

ABSTRACT. In this paper is to design a four element multi-input multi-output (MIMO) antenna for ISM Band applications. Rectangular patch and micro strip terminated coupled lines (TCL's) are used for generation of the filtering function. Wide number of transmission zeros can be initiated in spurious band by changing length of open circuited stubs and parallel coupled lines. A wide harmonic suppression is authorized by locating the transmission zeros in a suitable place. To indicate the proposed method a filtering patch antenna which is in wide stop band is delineated and then it is put in an application to 4-element MIMO antenna. The antenna is designed, simulated and the outcomes are computed. The obtained results are very satisfactory.

ABSTRACT. A compact asymmetric co-planar strip (ACS)-fed mmWave 5G antenna with 6.5-7.5 dBi end-fire gain is presented. Proposed antenna is wideband operating from 26-32 GHz with fractional bandwidth of 20%. Proposed single element antenna is having dimensions of 6 × 10 mm2 thus occupying small physical footprint which results in easier integration with mobile terminals. Proposed antenna achieves 1-dB gain bandwidth of 20% which determines the pattern integrity over whole operating band. Front-to-back ratio is more than 13 dB over the whole operating band. Orthogonal pattern diversity is achieved at 28 GHz thereby enabling smartphone usage in both portrait as well as landscape mode. Proposed antenna achieves reasonable gain for the available aperture.

ABSTRACT. A four-element dual-band multiple-input-multiple-output (MIMO) antenna based on co-axial probe fed microstrip circular patch is presented in this paper. The proposed antenna resonates at 3.72 GHz and 4.35 GHz. The higher resonant frequency is the conventional one of the circular patch antenna. The lower one is obtained by introducing a λg/2 slot in the ground plane. The port isolation at the lower frequency is enhanced (better than 15 dB) by incorporating simple arc-shaped slots in the ground plane. The ECC value is within the accepted range. The design possesses simplicity as well as a large one-dimensional array can be designed using the proposed MIMO antenna.

ABSTRACT. In this paper, the design and analysis of an efficient wireless power transfer (WPT) system to power the bio-implantable medical devices is presented. Herein, the radiating principle of the antenna is utilized to design the proposed system. A CPW fed ring slot antenna is considered as receiving (Rx) element, whereas a simple patch antenna is used as transmitting (Tx) element to construct the WPT link. The system is designed to operate at the industrial, scientific, and medical (ISM) band of 2.45 GHz. The alumina coating is used around the implant ring slot to eliminate the direct contact with skin tissue and make the Rx antenna bio-compatible. Also, a metamaterial slab with zero-index property is placed above the skin layer in the proposed design to improve the power transfer efficiency of the system. Furthermore, the misalignments between the Tx and Rx elements is studied to show the practical applicability of the proposed design. Finally, the specific absorption rate (SAR) analysis is performed to indicate the effect of the WPT system on the human skin tissue model.

ABSTRACT. This paper proposed a planar, small size printed microstrip line fed modified rectangular shape ultra-wideband antenna having dual band-notched response. By incorporating pair of L-shaped slots on the patch and triangular shaped electromagnetic band gap structure the band notched response can be realised. The presented antennas are optimized using IE3D, fabricated on low cost FR-4 substrate with dielectric constant 4.3 followed by measurement. The measured results indicate that the presented antennas having dimensions of 60mm × 80 mm × 1.6mm has impedance bandwidth in frequency range 1.5-10.6 GHz with Return Loss ≤ -10 dB, except 2.94-3.65 GHz and 5.2-5.76 GHz. 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. Additional conditions which are necessary for reducing RCS of complex objects using checkerboard metasurfaces are presented. It is demonstrated that the checkerboard metasurfaces are not sufficient to reduce the RCS of complex structures like dihedral corners where fields undergo multiple reflections. All the conditions are validated using the simulation results.

ABSTRACT. We proposed a novel type Hybrid Plasmonic optical triangle Nanoantenna with an structure of silicon of insulator. This Nanoantenna is designed for optical telecommunication wavelength of 1550, 1310nm. It provides the wide optical frequency range from 175 to 244 THz and it can be used for broadband Nanophotonics application. The 10dB bandwidth of the proposed antenna is more than 68 THz. Here simulation is done by CST studio software using a finite element method. The proposed Nanoantenna has satisfactorily gained 7.792, 5.667 dB and reflection ratio -12.86 and -13.56 dB at an optical telecommunication wavelength of 1550, 1310 nm respectively.

ABSTRACT. This paper presents a metasurface based circularly polarized quad-beam generating system. The system consists of two layers. The bottom layer splits the quasi-spherical incident beam of a MSA into four individual reflected beams in diagonal directions. The top ultra-wide band (UWB) meta-transmit-screen is a linear to circular polarization converter. This screen converts four reflected LP-beams from the bottom surface to CP-beams. Measured and simulated results follow each other. This multi-beam system may find applications in future 5G and IoT devices.

ABSTRACT. A compact dual-band Microwave Energy Harvesting (MEH) System is proposed in this article, in which omnidirectional antenna system is presented to receive the available radiation from WiFi routers at 2.4 GHz and 5.2 GHz frequency bands. The antenna system is followed by a Schottky diode-based rectifier to transform the received RF signal into a pulsating DC signal. To provide the proper impedance matching between antenna and rectifier, Frequency-Dependent Complex Load (FDCL) based impedance matching network is also proposed. By introducing the impedance matching network, Power Conversion Efficiency (PCE) of 64.04% at 2.4 GHz and 9.15% at 5.2 GHz is achieved for the overall rectenna system. Detailed investigation of various results such as S-parameter, Gain, radiation properties of the antenna, and Power Conversion Efficiency, is done in this paper

ABSTRACT. SAR payloads are generally used on-board all-weather imaging satellites. When compared to optical payloads they are found more suitable for target detection applications in absence of sunlight. Their working principle is based on transmission and reception of pulses of predefined pulse characteristics. The reflected pulse from earth terrain is analysed and processed based on the changes in the transmitted pulses. This analysis provides all the necessary information regarding the terrain. The effectiveness of the image generation depends on the accuracy of the desired pulse that is transmitted. Thus there is a need for characterizing the transmitted pulses for all the relevant parameters. This paper provides an automated scheme to characterize the transmit receive modules in a typical LFM (Liner Frequency Modulation) SAR payload. This scheme includes a test set up comprising of various COTS measurement instruments. It also includes an automation software which conducts all the measurements using the test set up and presents the results in a standard form.

ABSTRACT. Presently, with the advancement in wireless communication, number of RF systems required to be integrated on a single platform has increased with a corresponding decrease in the inter antenna spacing. When multiple antennas are installed on a platform, the radiation pattern of an antenna is affected by the proximity of nearby antennas. With out of band antennas placed adjacent to each other, prime focus is always provided on mutual coupling between the antennas to ensure that the systems are EMC compatible. Very fewer studies are made on radiation pattern variation due to out of band interference. The operating frequency or resonant length of nearby antenna and inter antenna spacing are the key factors causing variation in radiation pattern. This paper summarizes the dependence of radiation pattern of a monopole over a ground plane on frequency, size and separation of an interfering monopole. The far field gain of monopole antennas at out of band frequencies is discussed. The out of band gain of the interferer is found to have a direct relationship on mutual coupling and interference levels. S21 at the operating frequency is found to change by more than 20dB with interferers of different resonant frequencies. The dependence of S21 on the gain variation and the effect of inter antenna spacing on mutual coupling are studied. Out of band gain of the interferer or S21 at the reference antenna frequency is found to have negligible effect on radiation pattern of reference antenna compared to electrical length of interferer.

ABSTRACT. Proximity fed wide band gap coupled designs of rectangular microstrip antenna with combination of various ring shaped patches are presented. Single proximity fed rectangular microstrip antenna yields the bandwidth of 427 MHz (33%) with broadside peak gain 7.6 dBi. Further enhancement in gain and bandwidth is achieved using multiresonator technique and parasitic ring shaped patches. Gap coupled structure of rectangular microstrip antenna with two adjacent layers of two and four ring shaped patches provides optimum VSWR bandwidth of more than 970 MHz (65%), showing peak gain 9.68 dBi. The presented antenna structure is simple to implement and experimental results of fabricated prototype antenna shows close agreement with the simulated results.

ABSTRACT. In this paper a polarization-insensitive rasorber with wideband absorption and narrowband transmission at lower frequency is realized. The structure is realized by using resistive ink for obtaining absorption and lossless bandpass filter for transmission. The filter realized here is a double layered structure printed on two sides of FR4 substrate. The transmission is obtained at 5.2 GHz with an insertion loss of 1.48 dB. The absorption is achieved from 8.07 GHz to 18.12 GHz. Thus absorption is achieved in whole X and Ku bands. Experimental verification of the structure has been carried out which shows good agreement with the simulated results.

ABSTRACT. Compact antenna test ranges are used for fast and accurate measurement of satellite antennas and payloads.The measured performance of compact range feed dictates the quality of Quiet zone at CATF. A Dual Linear Q/V-Band feed compliant to standard compact range feed specifications was designed. The designed feed will be used for RF characterization of advance communication payload. In this paper, design aspects and simulated results of proposed feed are discussed.

ABSTRACT. This paper investigates the UWB off-body channel characteristics for a triangular-shape base station (BS) configuration with the focus on body-centric localization applications. An experimental study in a cluttered indoor environment is carried out with the miniaturized UWB Vivaldi antennas as base stations and CPW-fed UWB circular monopole antenna as the wearable antenna. The channel parameter values such as path loss magnitude/rms delay spread is lower (50-56 dB/0.5-4 nsec) for the non-obstructed paths in comparison to the obstructed paths (60-65 dB/10-25 nsec) caused due to the body presence in the localization environment. For the different positions of the human subject analyzed, the type of channel links formed depends on the BS location. The results obtained have an average accuracy of the order of 3 cm, demonstrating time-difference-of-arrival based high precision UWB localization. The work signifies the influence of the indoor environment, selection of antenna type and the human subject on the body-centric propagation channel links which has direct effect on the localization accuracy.

ABSTRACT. Green’s function has been formulated using the method of generalized reflection and transmission coefficients for arbitrary directed electric point source, which is placed in multilayered spherical media. To verify the formulation three-layer hemispherical DRA excited by coaxial probe has been taken and computed results are verified with HFSS simulation. To resolve the current on the surface of the probe, moment method with piecewise sinusoidal basis and testing functions are used, from which the input impedance, reflection coefficient and radiation pattern have been obtained. Maximum impedance bandwidth of 63.22% and 48.75% for center and offset coaxial probe excitation have been achieved respectively.

ABSTRACT. This paper presents a new copper sheet antenna in which at L-Band (L5: 1.176 GHz, L2: 1.227 GHz, L4: 1.379 GHz, L3: 1.381 GHz and L1: 1.575 GHz) linear polarization is achieved by introducing copper sheet resonant braches & can be used for modern navigation system. The return loss provided by the proposed antenna is S11 < -10 dB for L-Band frequencies and Wi-Max band 4/5 (3.3-3.6 GHz) as per the simulation and measured by the Vector Network Analyzer (VNA). This antenna is suitable for Wi-Max applications also. The proposed linearly polarized single feed antenna can be integrate with communication devices because of its small size, light weight and low profile. For the validation of its performance a commercially available GPS module is integrated with the proposed antenna and the measured results are very close to desired values.

ABSTRACT. A compact circularly polarized (CP) rectangular dielectric resonator antenna (RDRA) has been inspected in this paper for WLAN, Wi-Fi, Bluetooth and small satellite applications. The dielectric resonator antenna is singly fed by the combination of microstrip line and flat metallic strip/ conformal strip and excited with TE111 fundamental mode. The CP is generated by two flat metallic strips connected perpendicularly to microstrip line and to DR separated by quarter wavelength is exciting TEx δ11 and TEy 1δ1 orthogonal modes. The left-hand circular polarization (LHCP) has been achieved due to height variation in the flat metallic strips. At last, the designed antenna is productive of 19.2% impedance bandwidth from 2.13–2.77 GHz and 12.4% of CP bandwidth from 2.23–2.53 GHz. The designed antenna (0.4λ0) is considered to be compact size because the size proposed is smaller than conventional (0.5λ0) radiator with consistency in the gain (LHCP) above 4 dB and radiation efficiency all over the propose band.

ABSTRACT. Theoretical investigation on Cylindrical Dielectric Resonator Antenna (CDRA) using imperfect wall boundary condition is presented here for TMz modes for the first time, hitherto unreported. Approximate expression for eigenfunctions and eigenvalues are given here for different modes. Simple formula is given to predict the resonant frequency. Numerical and graphical both solutions are presented here. Theoretical results on resonant frequency are compared with measured data and data obtained using 3D EM simulator HFSS to show the accuracy of our theory.

ABSTRACT. In this paper, a discontinuous annular ring monopole antenna is presented for wideband circular polarization. A monopole is used to excite grounded annular ring. A small portion of the grounded annular ring is removed in order to generate wideband circular polarization. A functional prototype is fabricated and measured. The measured impedance bandwidth (S11 < -10dB) is 43.62% (5.86 GHz-9.13 GHz) and axial ratio bandwidth (AR $\leq$ 3 dB) is 30.5% (6.27 GHz- 8.47 GHz).

ABSTRACT. The performance of a dipole antenna kept close to a high impedance surface (HIS) and fed directly by a coaxial feed is studied and it has been observed that the high impedance surface can choke the unbalanced current thus resulting in acceptable balance performance. We also present a simple modification to feed arrangement that works like a balun and further enhances the performance of the antenna. The proposed idea is tested on three different types of HIS reflectors for analyzing the performance of the feed as well as the antenna.

ABSTRACT. To accomplish promises of 5G technology like blazing speeds, massive throughput capability and ultra-low latency, antennas should be designed having compact designs, high gain, high efficiency, very low return loss, and very low ECC. To achieve all these requirements, researches are required to switch to array and MIMO antennas with low loss tangent substrates such as Rogers Duroid, etc. The proposed design is a combination of an array and MIMO so that all the needed requirements can be fulfilled in 5G in the best possible manner. A 2 x 8 array- MIMO antenna is designed on Rogers Duroid 5880 substrate with substrate’s dimension of 23:83 x 53:52 x 0:79 mm3. Each patch with inset-feed is uniquely designed with radius, ’r’ = 1.44 mm to achieve sharp peak at 28.0 GHz resonant frequency. The gain of 10.67 dBi and radiation efficiency of 88.2% is achieved at 28.0 GHz in 27.572 - 28.648 GHz frequency band with respect to 2:1 VSWR band.

ABSTRACT. This paper presents analysis and design of substrate integrated waveguide (SIW) based microstrip patch antenna array using FEM based solver. It emulates the performance of a cavity backed patch antenna array and helps in designing a wide band wide scan antenna array. It helps in realization of a low profile antenna structure free from surface waves to a larger extent by getting rid of bulky and fabrication intensive metallic cavities required conventionally to inhibit surface wave propagation in substrate to remove scan blindness in phased arrays. The antenna shows a bandwidth of around 500MHz in X-band with 3dB beamwidth >90o. It also shows an 16 x 16 array performance. The work finds application in phased array radars.

ABSTRACT. This paper presents a broadside radiating wideband array antenna at 26.5 GHz. Both the TM₁₁ and the next higher order mode, TM₂₁ are excited on a single circular patch sitting on a large ground plane. The combination of these two modes provides elliptical beam in the broadside direction. Then, this patch is used as the basic radiating element for an array antenna. Because of the shaped radiation pattern, a 1 × 2 half wavelength array of the proposed antenna provides similar pattern like a 2 × 2 array of circular patches operating in only TM₁₁ mode. With same inter element distance, a 1 × 2 array gives better performance in terms of gain bandwidth and size requirement as compared to conventional 2 × 2 array. Individual element size is slightly larger than the conventional TM₁₁ mode antenna. But, overall size of the array antenna is reduced to 50% without degrading the gain value. Further, the mode mixing technique provides a wide bandwidth and lower side lobe level. A prototype array element is fabricated in 1.52 mm thick RO4003C substrate. It provides an average broadside gain of 7.1 dBi with gain variation less than 0.8 dBi over 25.35-27.65 GHz. The side lobe level is less than -14 dB from the broadside gain. Average total efficiency of the antenna is 86.6%.

ABSTRACT. In this paper, an eight-element dual-band multiple-input and multiple-output (MIMO) antenna system for future sub-6 GHz fifth generation (5G) smartphone application is proposed. The proposed dual-band antenna is consists of a coupled-fed inverted-L and F-shaped monopole elements with a small size of 12.5 × 5.2 mm2 which are printed on two long side frames of the smartphone. The dual-band MIMO antenna system is designed to cover both 3.5 GHz and 4.9 GHz operating bands with the antenna efficiencies over 76% at lower band and 49% at higher band are obtained respectively. Good isolation of -12.60 dB for the lower band LTE 42/43 (3.4–3.8 GHz) and -17.95 dB for the higher band (4.8–5.0 GHz) without decoupling structure are achieved. The calculated ECCs and diversity gain (DG) is less than 0.1 and 10 respectively which shows a favourable candidate for MIMO diversity performance within sub-6 GHz 5G smartphone applications.

ABSTRACT. Phased array antenna calibration is a technique to compensate phase and amplitude difference between the radiating elements due to its variation in T/R modules and feeding network. Different techniques and methodologies of active phased array calibration with help of embedded couplers with active/passive LRUs are developed such as coupling radiating elements, microstrip /stripline etc. These coupling measurement becomes the reference values with respect to which attenuators and phase shifters of phased arrays are adjusted during calibration. A cavity back antenna as a radiator is designed for the large phased array antenna and a leaky coaxial cable is buried within the cut of the cavity wall. Periodic lateral slots on the outer conductor of coaxial cable is introduced to leak the electromagnetic field to couple with radiating element. This leaky coaxial cable is used as a coupler for the measurement of amplitude and phase difference between the radiating elements active circuit. Measured coupling between the leaky coaxial cable and the radiating element is used as reference to adjust the amplitude and phase among the elements for phased array calibration.

ABSTRACT. In this paper, a dual band full duplex monopole
antenna is proposed for WLAN application. For dual band operation an L-shaped arm is added to both transmitter and receiver
antenna. Receiver ports of the proposed bi-static transmitterreceiver antenna is fed through the differential ports of a
dual band ring hybrid coupler to achieve isolation between
transmitting and receiving ports. The transmitting and receiving
antennas both resonate at 2.42 GHz and 5.25 GHz. The proposed
structure gives an isolation of 41 dB and 56 dB at 2.42 GHz and
5.25 GHz respectively. At 2.42 GHz and at 5.25 GHz the proposed
structure gives broadside peak gain of 4.17 dBi and 6.8 dBi and
3.6 dBi and 5.25 dBi for transmitting and receiving antennas
respectively. The proposed antenna system is fabricated and
simulated results are experimentally verified. Measured results
are nearly similar to the simulated results.

ABSTRACT. A novel low-profile broadband slot antenna is proposed in this work. Instead of traditional slots, fractal-geometry based Defected Ground Structure (DGS) is configured for the very first time in the conventional slot antenna, to achieve the broadband radiation properties in 15.76-93 GHz frequency range. Proposed structure is printed on 1.52 mm thick, low loss substrate Rogers 4232, with a relative permittivity of 3.2. The overall dimension of the proposed structure is 25 mm35 mm which can achieve at least 142% fractional bandwidth in its operating frequency range. Predicted, average gain of 4.3 dBi and the peak gain of 7 dBi is maintained in the entire frequency range by the proposed structure. Laboratory prototype of the antenna was fabricated and experimentally measured and measured S11 results are found to be in good agreement with the simulation results. Detailed investigation of radiation mechanism of the proposed antenna in such a wide frequency range is carried out by analyzing its surface current distribution at some intermediate frequencies. The proposed antenna can find its applications in short-range communication network for future mobile technologies like 5G.

ABSTRACT. Three essential data modes are observed for mobile terminal data usage and hence three conformal elements are presented with shared ground for least physical footprint with reduced SAR. First, a strongly resonant inset fed microstrip patch antenna with 90° bend is investigated which offers an impedance bandwidth of 2 GHz centered at 28 GHz and a forward gain of 9 dBi for an effective radiating volume of 0.082(λ_0)^3. The second element is a conformal tapered slot antenna optimized for the corner bend which resonates at 28 GHz with a gain of 7 dBi. The third element is a conformal tapered slot antenna loaded with a parasitic ellipse with a gain of 9 dBi and aperture efficiency of upto 80%. All the three elements are integrated with a common ground for pattern diversity.

ABSTRACT. 5G will bring major changes in user experience in terms of speed, capacity and bandwidth. In 4G, the antennas were either in 2x2 or 4x4 configuration. But in 5G there will be greater traction and need for 16x16, 32x32, and 64x64, and potentially higher combinations in the long-term.i.e. Massive MIMO is no longer a myth but a reality. The use of mmWave bands in 5G is yet another challenge, where antenna array design should also compensate the huge loss. Hence antennas have a huge role to play both in capacity and coverage enhancement.

This paper is a review on some of the major trends in 5G antenna for cellular infrastructure, from an industry perspective, gives an overview on Major 5G antenna requirements based on various use cases, highlights the challenges in 5G antenna deployment and design, discusses the trending deployment and design trends, substrate selection criteria for 5G NR antennas.