ABSTRACT. Microwave propagation in materials depends on the electromagnetic properties of a medium. The complex permittivity is a measure of the ability of a dielectric to absorb and to store electrical potential energy. The loss tangent, tanδ, is indicative of the ability of the material to convert absorbed energy into heat and hence limited propagation. Ceramics have excellent dielectric, magnetic, thermal and mechanical properties. The brittleness and high processing temperature of ceramics lead to the difficulty in fabrication of complex shapes. Many of the polymers satisfy the criteria of low relative permittivity (εr) and low dielectric loss required for high frequency applications. The major disadvantages of the polymers are their high value of the coefficient of thermal expansion inferior magnetic properties, tensile strength and thermal conductivity. This review paper will discuss some of the important electrical and mechanical properties of ceramics and polymers wrt to microwave propagation.

ABSTRACT. This paper demonstrates the use of evolutionary methods for synthesis of antenna. Microstrip line fed rectangular microstrip antenna for WLAN band is the example antenna. Analysis of the synthesized antenna for 5.9 GHz uses CST microwave studio for simulation and compares its result with measurement on a prototype. A comparison of genetic algorithm (GA) based synthesis with that of differential evolution (DE) indicates the later as a better choice.

ABSTRACT. In this paper, a Ku-band grounded coplanar waveguide (GCPW) to substrate integrated waveguide (SIW) transition is presented. The proposed transition is suitable for efficient planar excitation of the substrate integrated end-fire antennas realized using thick substrates. A prototype of the proposed transition is designed and simulated using CST microwave studio and parametric studies are performed on the simulated prototype. The lateral via fence width, central strip width and coupling slot width of the GCPW section are optimized, in order to achieve the leaky wave higher order mode suppression in the GCPW section and significant mode matching improvements at the GCPW to SIW interface. The proposed transition is realized using 1.57 mm thick substrate and exhibits maximum insertion loss of 0.4 dB with return loss better than 20 dB over the entire operating Ku-band.

ABSTRACT. A compact antenna for medical implant communication service (MICS) band operating at 403.5MHz is presented. The antenna is developed using commonly available low cost FR4 substrate with dielectric constant 4.4. The overall size of the antenna is 16.5mm x 29.02mm, which is very compact at its operating frequency.

ABSTRACT. The performance of terrestrial or space to earth communication system operating above 10 GHz is severely degraded due to the presence of rain drop size and its distribution in the tropical climate. In mm wave frequencies, rain attenuation and cross polarisation of radio signals becomes major limiting factors for the performance of communication system. This has generated interest in the studies of rain induced attenuation and depoplarisation for terrestrial or space to earth path communication and development of reliable and accurate prediction models required for the system design. Depolarisation of radio signals due to rain drop size distribution can cause interference or cross talk in radio signals, where polarisation is used to provide isolation between vertical and horizontal polarised radio signals as in the case of frequency reuse. In this paper, Cross Polarisation Discrimination (XPD) models have been developed based on co-polar and cross –polar attenuation at 30 GHz vertical and horizonal polarised radio signals during rain events using rain attenuation data measurement of 5 Km- line of sight (LOS) link at Dehradun, India. The variation of XPD with co-polar attenuation and rain rate have been described for vertical and horizontal polarised transmitted radio signals at 30 GHz.

ABSTRACT. This paper presents temperature dependent electromagnetic design of dielectric wall for application in radomes for high speed airborne platforms. The electromagnetic parameters of dielectric wall are computed using two models. The first model, called the `3 layer model', consists of the inner homogeneous dielectric shell with the outer coatings of the ablative layer and the paint layer. The second model, called the `Inhomogeneous Planar Layer model', takes into account the temperature gradient across the inner shell. Equivalent transmission line method is used to compute the transmission coefficient and insertion phase delay. The temperature dependent thickness optimization of the dielectric wall is performed using both the models. The dielectric wall is analyzed in the low and high velocity modes of operation. The changes in performance due to increased temperatures and ablation of outer layers are predicted.

ABSTRACT. In this article, a compact multi-port circularly polarized (CP) multiple-input-multiple-output (MIMO) antenna with a reflector ring is presented. The reflector ring used in this work reduces the interference between the CP radiation from closely spaced single antenna elements and restores the 3-dB axial ratio bandwidth (ARBW) . Besides restoring the 3-dB ARBW the reflector ring also serves the purpose of ensuring equal reference voltage in the proposed MIMO antenna. The proposed antenna efficiently radiates CP waves for 5–5.5 GHz band and has satisfactory diversity performance. A prototype of the proposed MIMO antenna has been fabricated and measured successfully.

ABSTRACT. In this paper, we discuss the full modelling of slow wave spoof plasmonic metamaterial based transmission lines at THz frequency. In the presented work, back to back transition from CPW, coplanar strip and microstrip to spoof plasmonic mode have been designed and their performance is analyzed and compared. The designed transmission lines are of same physical dimensions of 3.5 mm X 0.6 mm and have a cut off frequency of 1.25 THz for all. Simulated reflection and transmission losses are below 10 dB and 5 dB respectively. For different frequency bands, individual transmission line has different transmission efficiency. It is observed that at lower frequency, microstrip based conductor backed SSPP transmission line and coplanar strip to SSPP transmission lines have good transmission efficiency and at higher frequency, CPW line offers better transmission efficiency. Also, microstrip based conductor backed transmission line provide better performance as compared to coplanar strip. The above mentioned spoof plasmonic metamaterial based transmission lines will have a potential application in plasmonic integrated circuits and systems.

ABSTRACT. Glove integrated solid and segmented solenoid antennas are investigated in this paper. Various techniques for enhancing the magnetic field strength such as, placing a parasitic solenoid loop close to the driven solenoid, lumped capacitor loading, and using a reflector is also discussed. The detailed study is done to choose a proper segment length in segmented solenoid antennas to obtain a higher magnetic field strength near the solenoid structure. Three prototypes (solid solenoid, segmented solenoid, and segmented with parasitic solenoid) are fabricated by using copper tape as a metal strip. Performance in terms of impedance matching and magnetic field strength are measured and compared. Further, a simple feeding method is investigated for segmented solenoid antennas. Proposed segmented solenoid antenna with parasitic loop is more suitable for near field RFID applications.

ABSTRACT. An L-resonator based chipless RFID tag has been introduced in this paper for tracking and identification purposes in a blood bank management system. Four bits of data are being encoded in the unlicensed band between 5.1 to 5.9 GHz, where the first three bits are used to identify the blood group and the fourth bit is used for verification purposes. The proof of concept has been shown by first designing the tag and antenna using CST Microwave Studio and fabricating on a ROGERS RT 5880 and FR-4 substrate, respectively. The tag and antennas have been tested using a Vector Network Analyzer (VNA) and the results reveal good scattering parameter results in the frequency of operation. The compact size of the tag and the antenna, make the overall tag suitable as a smart label in a blood bank management system for use in blood bags and patients.

ABSTRACT. In this paper, a high gain 16 ports MIMO antenna is designed at 60-GHz for millimeter wave applications. The proposed antenna consists of 16 ports, each port consisting of 1 x 2 antenna array. The designed MIMO antenna achieves a bandwidth (|S11| < -10 dB) of 1.6 GHz, covering a band from 59.12 GHz to 60.72 GHz, with gain of 19.86 dBi and directivity of 21.58 dBi . It gives the best results, compatible with IEEE 802.11ad standard for 60GHz wireless communication. Comparative analysis is carried out by adding number of ports to the antenna. The high gain antenna system is designed on 0.2 mm FR4 substrate with dielectric constant of 4.4 and loss tangent of 0.0004. The size of the proposed antenna is 48.56 mm × 21.82 mm.

ABSTRACT. In this paper, series fed tapered array antenna for base station massive MIMO (m-MIMO) application is proposed. A 5-element series fed array is considered as an antenna sub-array element for the proposed m-MIMO antenna system. The sub-array elements are tapered uniformly with respect to center element to reduce sidelobe level and mutual coupling from adjacent sub-array. Simulation for two and eight-element m-MIMO design prototype is presented. A two-element m-MIMO prototype is fabricated and measured for validation. A very closely spaced (0.08λ_0) sub-arrays offer mutual coupling less than –20 dB, azimuth and elevation half-power beamwidth of 105^0 and 30^0 respectively and side lobe level less than -20 dB.

ABSTRACT. A Compact MIMO antenna was proposed in this article. The designed antenna is compact in size with dimensions of 20 x 34 x 1.6 mm3.The patch antenna consists of two C- shaped elements facing each other and a hexagonal ring with a strip line which is placed in between the two C-shaped patch antenna elements. This model has a partial ground with mounted structures of inverted C-shaped strips, slots and a ring. In this model FR-4 material is used as substrate with permittivity (ԑ) = 4.4 and a loss tangent (δ) = 0.02. the proposed antenna is working under three bands, where the bands are under go condition of S_11≤ -10dB, those bands are 1.74GHz - 1.87GHz, 2.45GHz-4.15GHz and 9.62GHz – 11.13GHz with their respective bandwidth’s of 0.13GHz, 1.70GHz and 1.51GHz. The antenna can work in the bands of GSM, CDMA, Wi-Fi, Wi-Max, Maritime navigation, Aeronautical navigation(Ground), Radio location and fixed satellite services.

ABSTRACT. In this work, a novel triple-ultra wideband (UWB) Multiple-input multiple-output (MIMO) antenna with reduction in mutual coupling is proposed for 5G millimeter-wave (mm-wave) communications. The MIMO design consists of four antenna elements fed at the vertex. The antenna elements are loaded at the top and bottom of the substrate at a distance of 1.1 mm respectively to minimize the effect of mutual coupling. Thus, the isolation achieved a maximum of 36.26 dB. The dimension of the proposed MIMO antenna is 30 mm × 25 mm × 0.8 mm. A fractional bandwidth (FBW) of 51% (23.26-36.91 GHz) and a maximum gain of 10.27 dBi is achieved at 40.48 GHz. In addition, the radiation efficiency of more than 85% is obtained in the frequency range of 23.26 - 43.01 GHz. The peak envelope correlation coefficient of the proposed structure is less than 0.003. The designed antenna is simulated, fabricated and measured; a good agreement between simulation and measurement results were achieved. The performance of the proposed antenna is compared with the existing mm-wave MIMO antennas in literature.

ABSTRACT. This paper presents a very low profile fourelement printed dipole antenna suitable for wireless local area network (WLAN) access point application in a multi-input multioutput (MIMO) systems. Out of four-elements, two similar antenna elements are designed to operate in the 2.4 GHz band (of size 20×47 mm2) and other two elements are for 5.8 GHz band (of size 20×20.5 mm2). All four antenna elements are printed in a coplanar configuration on both sides of 1.6 mm-thick FR4 substrate to make it a 4-port MIMO antenna. Each dipole element of the proposed MIMO antenna is loaded by a triangular stub and fed by microstrip line with protrude ground plane. This makes the antenna as an efficient radiator from upper and lower part of antenna and generate almost omnidirectional radiation pattern. As per the simulation results, by optimizing the distance between the antenna elements in horizontal and vertical direction, an optimal isolation of -16.4 dB at 2.45 GHz and -19.7 dB at 5.8 GHz is achieved. The proposed MIMO antenna provides an impedance bandwidth (S11<-10 dB) of 29% from 2.16 to 2.88 GHz at port 1 and port 2 and from 4.91 to 6.55 GHz at port 3 and port 4, respectively. Measured results are found in close agreement with the simulation results.

ABSTRACT. A compact circular polarized antenna for multiband NavIC receivers is presented. Concept of stacked patches fed through single coaxial probe is employed. Two square patches are stacked one above the other to achieve dual band operation. The antenna is designed to receive L1 (1575.42 MHz) band GPS signal and L5(1176.45 MHz) band IRNSS signal. Principle of corner chopping is used to obtain circular polarization at L5 frequency band and a combination of corner chopping and stubs are used to obtain circular polarization and good return loss at L1frequency band. Realization aspects, simulated and measured results of the dual band stacked patch antenna are discussed here. The proposed antenna is designed, simulated and fabricated. This antenna has achieved a bandwidth of 2.1% and 3.5% at L5 and L1 frequency bands respectively. The measured gain at L1 frequency is 6.1dBi and at L5 frequency is 5.9dBi. This antenna is proposed to be used in launch vehicle applications to receive both GPS and IRNSS signals with omnidirectional coverage in L-Band.

ABSTRACT. A CPW fed design for Monopole Microstrip Antenna (MMSA) for multiband wireless application is proposed. Antenna has simple monopole with E- shaped parasitic patch inside the ground. Two higher resonant frequencies of proposed antenna are related to E- shaped parasitic patch and one resonant frequency can be flexibly tuned with little effect on the width of the monopole. Design of antenna operating at 2.34, 4.3 and 6.5 GHz with wide Impedance bandwidth of 348 MHz (2.17-2.55 GHz), 1821 MHz (3.6-5.45 GHz) and 1968 MHz (5.62-7.5 GHz) is simulated and prototype is fabricated on RO (εr= 2.2 and substrate height=1.57mm) low profile of 0.31λ, where λ is wavelength of the lowest resonant frequency 2.34 GHz at free space. Compact antenna is (40 mm X 40 mm) 0.31λX0.31λ. It may utilized in Bluetooth, Wireless Local Area Network for IEEE.802.11a (5.15-5.825 GHz), WiMax band and C-band (4-8 GHz) wireless applications.

ABSTRACT. In this paper, a modified Antipodal Vivaldi Antenna (AVA) with dielectric loading is designed for millimeter wave 5G applications operating in the 28GHz band. The proposed antenna has a wide impedance bandwidth operating from 24-35GHz (33%) with an endfire gain of 8-10 dBi across the operating band. To increase the endfire gain, the proposed antipodal Vivaldi antenna is loaded with dielectric substrate due to which there is gain enhancement of 1.5dB across the band. The flexibility of the proposed antenna is investigated to investigate the deterioration of the characteristics of the antenna. Detailed simulated and measured results are presented

ABSTRACT. The aim of this paper is to provide efficient technique for optimum performance of HF dipole antenna with minimum height variation. HF Frequencies are generally lower at the night and higher during the day due to ionospheric variations. Large range HF communication experiences limitation due to use of either multiple antennas or changing the antenna height at regular interval due to variation in HF frequencies. Various past research work w.r.t. HF frequency tuning focuses on either electrically small antennas or narrow band, dual band frequency tuning. However long range wide band HF antenna frequency tuning needed to be addressed. In present paper a channel length extension technique is used to vary the long range inverted V HF Dipole antenna resonance frequency while maintaining the actual Dipole length. With the employment of channel length extension technique most of day/night frequencies can be covered in a particular time slot resulting in very effective and accurate HF contact with least variation of antenna height. Resonance Frequency shifting (-3 M Hz) from 9.5 MHz to 6.5 MHz has been demonstrated by varying channel length for 10 M Hz inverted-V HF dipole antenna. Extensive trials were conducted to validate the performance results and same found as desired. The research work carried out in this paper will definitely enhance the efficiency of HF communication for various time slots and provide novel platform for optimum operational performance of HF antenna specially in the field of Defence and national security

ABSTRACT. A L1 band Circularly polarized microstrip circular patch antenna with conical radiation pattern (Null at bore sight) is presented in this paper. Higher order mode TM21 mode is excited in circular patch for conical radiation pattern. Antenna is fed by Wilkinson power divider (1:4) at four feed points. Two feeds (TM21, TM21*) are required for generating circular polarization and additional two feeds for cross–pol improvement and suppressing unwanted modes. Peak direction of beam can be varied by varying the dielectric constant of substrate. The antenna simulations show ≥10% Axial Ratio bandwidth (≤ 3dB), 6.3 dBi peak gain at ± 30⁰ from antenna axis and ≥20% impedance bandwidth (VSWR≤1.33).

ABSTRACT. In this paper, different shaped button antenna are analyzed to be suitable for wireless body area network (WBAN) by considering various design challenges like size, operating frequency, bandwidth requirement, and other challenges posed by the human tissues. The proposed antenna consists of a unique circular patch mounted on different button geometries for WBAN applications. This circular patch of diameter 15.5 mm consist a top moon shaped patch on substrate with permittivity of 2.2 and a conductive ground below the textile substrate of permittivity 1.4. The antenna is designed to operate in ISM band with resonance at 2.45 GHz and 4.6-6.4 GHz (30% BW), were the lower frequency provides the gain of 2.3 dBi which can be used for communicating with other body devices and upper frequency provides gain of 5.1 dBi useful for communicating other nearby devices in same band. To hide the moon shaped patch a denim superstarte is introduced and the effect of same on antenna performance is studied under various conditions.

ABSTRACT. A wideband dual polarized bowtie antenna for 5G applications is presented. The dual polarization is achieved by using two different bow-tie antenna elements placed in orthogonal orientation. The design consists of rectangular slots on the two arms of bow-tie antennas which enhances the port to port isolation. The unidirectional radiation pattern is obtained by placing a perfect electric conductor (PEC) ground plane at λ/4 distance. The radiating elements are designed to operate at 3.5 GHz. Measured results of the proposed dual polarized bow-tie antenna exhibit a bandwidth of 42.85% (3.1 – 4.6 GHz) and 11.4% (3.3 – 3.7 GHz) for a VSWR of < 2 and 1.5 respectively. An isolation of 28dB between the two ports and an average gain of 8.4 dB is measured for both the polarizations.

ABSTRACT. RF energy harvesting has gained momentum recently due to the quest for developing batteryless self-sustaining systems or enhancing battery life of existing systems. Development of selfpowered battery less sensors would be an integral part in practical realization of Internet of Things (IoT). Antenna design is crucial for enhancing the efficiency of the RF energy harvesting system. The talk would cover various challenges associated with antenna design for RF energy harvesting applications. It would also cover some of the solution proposed by our research group.

ABSTRACT. n his talk. efforts in the various license-exempt frequencies including sub-GHz for indoor propagation, RF design as well as constrained antenna design for various applications will be addressed. Additionally, our design initiatives in Ka-Band will be briefly touched as well as the industry expectations and status in IoT and “smart” electronics domain.

ABSTRACT. In this talk antenna measurements at different antenna test facility of Space Applications Centre will be covered. It includes the high accuracy measurement, measurement of antenna phase center, millimeter wave antenna characterization, multi-beam characterization and different antenna test measurement setups. It also covers the acquisition schedule and uncertainty budget.

ABSTRACT. n this talk, communication challenges in different types of satellites such as geostationary, interplanetary missions will be covered. Talk will focus on the practical experiences in Chandrayaan-1 and MOM missions. Increase in distance and decrease in solar power generation are the major challenges in any outer planetary mission. As the distance increases, the propagation delay also increases. Due to the delay in signal reception, autonomous decision-making system in spacecraft becomes essential. The talk covers various levels of spacecraft autonomy. Asteroids, Comets, Trojans, TNOs, inner planets, outer planets, moons of planets will also be discussed.

ABSTRACT. In this talk key areas where satcom technologies are inducted will be presented. Over view of SATCOM antennas in Past, present, Future will be discussed. New product, antenna developments, manufacturing facilities available in his organization is addressed

ABSTRACT. A CPW-fed dual wide-band directional antenna is designed, and an investigation carried out to improve the performance of the antenna using asymmetric artificial magnetic conductor is presented. The unit cell of the proposed AMC has a square patch geometry in which four rectangular slots have been etched out. The dual-band antenna is formed by a CPW-fed tapered monopole with V-shaped slot and is backed by an AMC reflector consists of 4 × 4 unit cells. The proposed antenna has dual wide-band response ranging from 2.23-2.81 GHz (580 MHz) and 5.01-6.5 GHz (150 MHz). The proposed antenna exhibits peak gain improvement of 4.48 dBi and 6.51 dBi at 2.4 GHz and 5.5 GHz respectively and has directional radiation pattern with front to back ratio (FBR) of 20.22 dB and 29.49 dB at 2.4 GHz and 5.5 GHz respectively. The proposed antenna also exhibits bandwidth improvement as compared to the antenna without AMC reflector over both 2.4 GHz and 5.5 GHz bands.

ABSTRACT. The importance of radio frequency identification (RFID) is prominent in this advanced technological era. Here a passive 3-bit RFID tag is presented for retail, biomedical as well as industrial applications. This tag is based on square split-ring resonator (SRR) concept. Here a new approach is presented by taking three coplanar rectangular split-ring resonators which perform as per expectation. The performance characteristics are obtained through design and simulation using CST Microwave Studio and validated through measurements. Based on measurement results, the tag can provide a maintenance-free environment for wireless applications, viz. goods tracking, identity detection, and health monitoring.

ABSTRACT. Abstract—This paper presents the application of artificial neural network in optimizing planar printed antennas Data generation for training the multilaye r neural network derived from full wave based solver to improve the accuracy of network. Back propagation algorithm and momentum method is applied for updating the weights during each iteration. Nonlinear Sigmoid transfer function has been used for hidden neurons while a linear function is chosen for the output neurons. Interpolation technique is also applied on the data set to reduce the computation time on the data generated by full wave based CAD software and to improve the accuracy for presenting large data. The paper also presents the comparison of test result with full wave based solver for validation and its computation time showing reduction.

ABSTRACT. In this paper, a dual-band ultra-thin compact polarization independent metamaterial absorber is proposed. The proposed absorber consists of two resonating structures i.e. a swastika-shaped and a square ring-shaped. The swastika shaped structure is enclosed within a square ring. The size and thickness of the unit cell are 6 × 6 mm2 and 0.015λ (where λ is the lowest resonating frequency), respectively. The combination of two resonating structures provides peak absorbance at 5.65GHz and 10.91GHz with maximum absorptivity 98.8% and 99.5%, respectively. The application platform of the reposed absorber lies in C and X band. The surface current distributions at 5.65GHz and 10.91GHz have been studied for a better insight of the absorption peaks. The simulation study confirms that the proposed absorber stable over wide angle under TE and TM polarization. Moreover, the proposed unit cell provides polarization insensitivity due to fourfold symmetric geometry.

ABSTRACT. This work highlights an unaddressed radiation feature through a comparative study between typical microstrip and dielectric resonator antenna structures. Variation of the cross-polarized (XP) fields over the full operating band is the main focus. The observation leads to precise designing of DRA - midband resonance being offset to the real operating frequency.

ABSTRACT. A tri-band rectangular patch having C shaped slot with a strip with partial ground plane is proposed. The antenna is fed through 50 ohm inset feed. The antenna occupies the size 38mm x 49mm. Triple band is achieved due to the strip slot attached with C slot and Partial Ground Structure (PGS). The antenna covers the 2GHz, 3.6GHz and 7.2GHz bands with impedance bandwidth 390MHz, 430MHz and 360MHz respectively. The simulated and measured results show good antenna performance for multiple applications in wireless communication.

ABSTRACT. The coupled fields between the slots are physically analyzed for wide 3-dB axial ratio beamwidth (ARBW) of a circularly polarized (CP) antenna. The square shaped CP antenna is decorated with a rectangular slot along one diagonal line of the patch and a pair of cross slots along another diagonal line. Dimensions of cross slots play a crucial role in adjusting the 3-dB ARBW of this CP antenna. This antenna offers the impedance bandwidth (IBW) of 83 MHz (2.443-2.526 GHz), CP bandwidth (CPBW) of 17 MHz (2.446- 2.463 GHz), and a maximum realizable gain of 4.28 dBic. The proposed left handed CP (LHCP) antenna exhibits wide 3-dB ARBW of 224º and 212º at = ࣐0° and = ࣐90° planes,respectively.

ABSTRACT. A broadband microstrip patch antenna is designed for broadband wireless application in this paper. Simple open-ended airplane shaped slot on the radiating patch top of the infinite ground plane is introduced to achieve broadband. The dimension of the patch is 0.284 λ0 ×0.265 λ0, (λ0 is the free space wavelength at 5.68 GHz). The two simulated frequency bands for the proposed antenna are 0.13 GHz (5.62 - 5.75 GHz) and 2.64 GHz (8 - 10.64 GHz). The measured frequency bands of 0.23 GHz (5.55 - 5.78 GHz) and 2.88 GHz (7.86 - 10.74 GHz) by the proposed fabricated antenna are achieved. The peak gain of 5.89 dBi at 10.5 GHz is achieved. The maximum percentage bandwidth of simulated and measured is achieved with 28.32 and 30.96%, respectively.

ABSTRACT. This paper proposes the design of linear microstrip antenna and array using L-probe feeding technique. L- probe is an attractive feed technique, which can be used to avoid the use of electrically thick substrates. This feed technique is used to design antenna array with high gain. A 15-element linear array is designed to give bandwidth from 5.71 -5.91 GHz (|S11| < -10 dB) with peak gain of 18.9 dBi with stable radiation pattern over the bandwidth. The sidelobe level is -14.3 dB at 5.86 GHz.

ABSTRACT. Analysis of protective structure’s effectiveness against Electromagnetic Interference (EMI) in a High Voltage Laboratories is very significant in today’s advancement in Science. This paper describes the shielding effectiveness (SE) of a Faraday cage with dimensions 6.2m X 5m X 8.2m for an environment comprising a High Voltage laboratory. However, simulation models are limited; the cage is scaled down by a factor of 50 and is simulated in EMPro© 3D EM simulation software. Finite Difference Time Domain (FDTD), computational technique is evolved as 3D EM field solver since it provides best memory efficient results for the considered structure. The obtained simulation results are compared with practical results and outcomes are recorded. The effects of cage’s thickness, and material on its SE are also determined. Average SE of 18 dB is obtained for our structure and the ways to further improve the SE are suggested.

ABSTRACT. This paper presents a novel complex permittivity measurement using transmitted-power function enforced at multiple frequencies. The method can easily retrieve the dielectric constants of low-loss and lossy materials utilizing the transmitted power without the need for phase information. Simulations results show a high accuracy level of the proposed permittivity reconstruction technique, making the technique an attractive candidate for fast and inexpensive complex permittivity determination without the need for a vector network analyzer.

ABSTRACT. This paper presents a single layer metamaterial absorber design and fabricat based on resistive ink printed on FR-4 sheet. This proposed structure has more than 90% absorption in S and C band of microwave frequencies with a fractional bandwidth of 120%. The thickness and unit cell size of this structure is only 0.075λL and 0.120λL (λL is the wavelength corresponding to the smallest frequency of more than 90% absorption). The designed structure is polarization insensitive and efficient for an oblique incidence of the wave. Small thickness, light weight and conformal behaviour of the fabricated absorber may have potential wide range applications.

ABSTRACT. Establishing of parabolic reflector antennas is required for any satellite communications. The important parameters of antenna structure are Gain, Pointing accuracy and Natural frequency. This research intends to understand the free vibration characteristics of antenna structure with field test and numerical analysis. Antenna servo system band width depends upon antenna stiffness and structure fundamental frequency. Usually string snap method followed for finding of frequency physically. But it is destructive test. Hence frequency obtained from numerical analysis only considered for deciding the servo system. Now a days, using microtremor (velocity sensor) frequency of antenna can be measured without any damage/destriuction to antenna. In this paper, 7.2m diameter full coverage antenna is considered for field test and numerical analysis and compared the results.

ABSTRACT. In this paper, a compact dual-band rectenna operating in the frequency range of 4.8-5.2 GHz (Wi-Fi) and 7.7-7.9 GHz has been proposed. The antenna dual-band is achieved at a feed length of 38 mm by varying the feed length. The dual-band rectifier is designed with the help of Villard voltage doubler circuit with single T-matching network. The proposed rectenna has been implemented by integrating the rectifier to the antenna. The simulation results of antenna, rectifier, and rectenna are performed individually. The antenna is fabricated, various parameters measured, and compared with the simulated results. The maximum measured power conversion efficiency (PCE) of rectifier and rectenna of 51.7 % and 48.5% have been obtained.

ABSTRACT. A low loss sectorial disk microstrip power divider is developed and employed for characterization of on-board amplifier. Standard topologies employ 4-port directional couplers attached together so as to simultaneously test various parameters such as frequency, power and modulation index for the on-board operations. In case of low power applications simple sectorial disk planar power divider can measure these parameters. The realized divider is totally planar and integrated with multiple measurement equipment for the amplifier characterization. The measured results of the developed power divider show close analogy with the simulated values. The proposed topology is further integrated with the amplifier test bench set-up at C-band for the complete characterization and results are validated with the typical measurement using the standard topology.