K. P. Ray

Low-RCS and Polarization-Reconfigurable Antenna Using Cross-Slot-Based Metasurface

This letter presents a polarization-reconfigurable compact slot antenna with reduced radar cross section (RCS) using an asymmetric cross-shaped metasurface (MS). The proposed MS can reconfigure the polarization of the slot antenna between right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), and linear polarization (LP) by rotating it with respect to the center of the slot antenna. In addition, the MS reduces the RCS of the slot antenna significantly in all polarization states. The cross-slot MS is placed just over the planar slot antenna without any air gap. The simulated monostatic RCS of -19.5 dBsm is observed at 4.4 GHz for LHCP and RHCP cases and -17.0 dBsm for LP mode of operation. Antenna performance in terms of its input matching, far-field parameters, monostatic RCS, and axial ratio are measured at its three polarization states, which are in agreement with simulated results.

Dual-Band Circularly Polarized Split Ring Resonators Loaded Square Slot Antenna

A dual-band circularly polarized (CP) microstrip line fed slot antenna using a set of split ring resonators (SRRs) is proposed in this communication. Outer ring connected SRRs are placed on the back side of the slot to create the CP upper band. Diagonally opposite corners of the slot are truncated, which together with the SRRs give CP response in the lower band. The proposed dual-band CP antenna provides design flexibility to control the resonance frequency and sense of polarization at the dual bands, independently. The proposed antenna is designed to operate at 3.1 and 4.7 GHz, which is fabricated and tested. The experimental results show the -10-dB impedance bandwidths of 400 MHz in both the bands and the 3-dB axial ratio bandwidth of 3.1% (from 3.05 to 3.15 GHz) and 4.2% (from 4.65 to 4.85 GHz) in lower and upper bands, respectively. Finally, a metallic cavity is used with the antenna to achieve a unidirectional radiation pattern with front-to-back ratio of more than 15 dB without affecting the impedance bandwidth and CP performance of the antenna.

COPLANAR WAVEGUIDE BAND REJECT FILTER USING ELECTROMAGNETIC BAND GAP STRUCTURE

This paper presents design and analysis of six different configurations of Coplanar Waveguide Band Reject Filters (CPW-BRF) using Rectangular Dumbbell Electromagnetic Band Gap (RDEBG) cell structures. The performance in terms of rejection bandwidth, attenuation, cutoff characteristics of the proposed design are found superior to the earlier reported CPW-BRF. Using cascading of six RDEBG cells, rejection bandwidth has been improved up to 2.8 GHz with attenuation of −38.8 dB and filter selectivity of 26.9 dB/GHz. In addition, the radiation losses have also been analyzed by extracting equivalent R, L and C values from electromagnetic (EM) simulation results. Fabricated CPW-BRF using four RDEBG cells has been analyzed. For the fabricated CPW-BRF simulated and measured results are found in good agreement.

Design of a novel CPW filter using asymmetric DGS

Two coplanar waveguide (CPW) low pass filter configurations based on rectangular dumbbell shaped Symmetric-DGS (SDGS) and Asymmetric-DGS (ADGS) have been designed and fabricated. For the designed filters, the equivalent RLC parameters have been extracted. Performance assessment of these filters has been carried out based on various parameters like, cut-off frequency, pass-band width, pass-band insertion loss, attenuation at resonant frequency, etc. The fabricated CPW-ADGS filter shows pass-band width of 0.9 GHz with attenuation at resonant frequency of -23 dB. IE3D simulation results and theoretical results show good agreement with measured results.

Dual band dual polarized frequency reconfigurable antenna using meta-surface

A frequency re-configurable dual band dual polarized antenna is proposed. This consists of a rectangular feed patch layer and two MS layers of same thickness. MS layers are made of rectangular loop based unit cells periodically placed in both X and Y direction. The total profile of the antenna is 0.07 λ0 only. Simulation result shows that the operating frequency of the antenna can be changed by physically rotating both the MS layers with respect to the centre of the patch antenna. As the MS is rotated the excitation and the polarization with the electric field of the patch to the MS layers change which changes the effective permittivity of the whole substrate and hence the frequency of the operation also changes. Measured results are well matched with the simulation results. At all the frequencies antenna has peak gain of more than 5.5 dB and the minimum efficiency is more than 89%.

VERTICALLY POLARIZED CAVITY BACKED SHORTED HEXAGONAL PATCH ANTENNA

A cavity backed conformal broadband compact hexagonal patch antenna is proposed that is fed using a co-axial probe. This horizontally mounted shorted antenna yields vertical polarization. The antenna yields 9.52% bandwidth centered around 1.05GHz. The simulated results of electrical parameters of this antenna are in good agreement with measured ones. This vertically polarized antenna can be used for IFF airborne applications.

Analysis of a single shorted rectangular microstrip antenna for 50Ωmicrostrip line feed

In this paper, analysis of a lower order and dominant mode of a rectangular microstrip antenna with a loading of the single shorting post has been presented. Microstrip line feed of 50 Ω impedance along one of the radiating edges with a single shorting post has been proposed for impedance matching. A detailed investigation of the rectangular microstrip antenna with and without single shorting pin has been presented and experimentally validated with good agreement.

A compact modified corporate feed network for antenna arrays with non-identical rectangular microstrip antenna elements

An antenna array with modified compact feed has been designed with non-identical elements using cosine square amplitude distribution with the purpose of reducing the first side lobe level. The proposed feed network uses an overall area of 25.47% less than that of a similar array with conventional corporate feed network. Experimental results of this six element array validate the theoretical parameters.

A Compact N-Way Wilkinson Power Divider Using a Novel Coaxial Cable Implementation for VHF Band

A novel implementation of N -way Wilkinson power divider using series and parallel combination of coaxial cables has been proposed in this paper. This arrangement results in a very compact power divider at VHF and lower frequencies, has good isolation between all the ports and is capable of handling high power with a low insertion loss. Frequency tuning and phase equalisation are easily accomplished using this technique. The measured results on fabricated 7-way and 4-way power dividers exhibited good input and output matching as well as amplitude and phase balance with an overall length of less than λ/8 at 221 MHz, with potential for further reduction in length.

Compact Broadband Directive Slot Antenna Loaded With Cavities and Single and Double Layers of Metasurfaces

In this paper, a compact wideband directive metasurface (MS)-based antenna is proposed. A pair of edge-fed slots, assisted by a fictitious short, is used to excite the MS layer which is made up of a periodic arrangement of rectangular loop-based unit cells along both the x- and y-directions. The proposed MS-based slot antenna is compact and provides good matching over the entire bandwidth with a broadside radiation pattern. A metallic cavity and an artificial magnetic conductorbased cavity are integrated on the MS-based antenna to reduce its backward radiation. Finally, a pair of edge-fed slot antennas combined with two layers of MSs having compact ground plane area of 1.04 λ02 (λ0 is the operating wavelength in free space) is proposed for the improvement of gain, bandwidth, and forward radiation. The overall antenna has a low profile of 0.05 λ0. The proposed configuration shows a 21% measured bandwidth with an average gain of 9.6 dB over its bandwidth. Over its bandwidth, the antenna efficiency is >89%. The design is validated by a fullwave simulation study followed by the experimental verification.