Krishnamoorthy Kandasamy

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.

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%.

SRR loaded slot antenna for multiband applications

A compact square shaped microstrip triband slot antenna is proposed. Two Split Ring Resonators (SRR) of the same configuration are loaded at one edge of the slot in a back to back orientation. The other edge of the slot is displaced with two 180° rotated SRRs with multiple slits. The additional bands are obtained from the resonance properties of the loaded SRRs. The antenna is simulated and measured. The resonance frequencies obtained are 2.7 GHz, 4.3 GHz and 4.7 GHz. A minimum bandwidth of 130 MHz is achieved.

Design of SRR loaded reconfigurable antenna for UWB and narrow band applications

In this paper, a reconfigurable antenna utilizing the property of negative permeability of split ring resonators is proposed for band notched UWB and narrow band applications. The proposed design yield the resonant frequency of the narrow band operation and notch frequency of UWB operation coinciding at 5.8 GHz frequency. The proposed antenna is simulated and measured. Radiation efficiency of 80% and 50% is observed for the UWB and the narrow band operation, respectively.

A novel circularly polarized / dual band dual polarized antenna using metasurface

In this paper a novel circular polarized/dual band dual polarized antenna has been proposed, which is validated experimentally using the meta-surface. First a 450 rotated rectangular loop based meta-surface is excited with a patch radiator to obtain the dual band dual polarized operation. Thereafter another same meta-surface is loaded on top of it to merge the two dual polarized band to obtain circular polarization. Appropriate rotation of the top meta-surface ensures maximum coupling with the X directed electric field from the bottom MS. Impedance bandwidth for dual band dual polarized operation is from 5GHz-5.28 GHz and from 5.6 GHz-5.75 GHz. For circular polarization response, impedance band width is from 4.8 GHz-5.77 GHz (Fractional Bandwidth of 19%). and 3 dB axial ratio is from 5.15 GHz-5.76 GHz. Measured gain of the antenna is 7.4 dB.

A high gain EBG backed slot antenna loaded with anisotropic mu-negative superstrate

A reduced profile directional and high gain slot antenna loaded with Electromagnetic Band Gap (EBG) cavity and anisotropic negative permeability medium (NPM) is proposed which is investigated numerically as well as experimentally. Measured result shows a good agreement with the simulation result. Bandwidth of the proposed antenna extends from 3.4 GHz-4.1 GHz (Fractional Bandwidth (FBW) of 19%). Significant improvement in gain about 7 dB is achieved as compared to the conventional slot antenna with E and H plane beam-width of 35.30 and 36.80, respectively.

Design of multi-band antenna using zeroth order resonator loaded with SRR and modified ground plane

A compact multi-band antenna using a zeroth order resonator (ZOR) loaded with a split ring resonator (SRR) and modified ground plane is proposed in this paper. The antenna resonates at 2.8 GHz, 4.3 GHz and 5.8 GHz. The antenna has a compact size of only 28.3 × 24 × 1.524 mm3. The ZOR antenna resonates at 2.8 GHz and the loading of SRR on the back side of the antenna produces the resonance at 4.3 GHz without affecting the ZOR mode. The modified ground plane provides an additional band at 5.8 GHz. The proposed antenna is simulated, fabricated and tested. The measured -10 dB impedance band width of 300 MHz, 350 MHz and 450 MHz is observed in the respective bands. Omni-directional radiation patterns are obtained at all the three bands.