Faculty Publications
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Publications by NITK Faculty
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Item Compact Wideband Circularly Polarized SRR Loaded Slot Antenna for Soil Moisture Sensor Application(Society for Microwave Technique, Technologies and System, 2020) Tharehalli Rajanna, P.K.; Rudramuni, K.; Kandasamy, K.– This paper presents a coplanar waveguide (CPW) fed corner truncated square slot antenna loaded with a split ring resonator (SRR) for soil moisture sensor application. The truncated corner square slot produces a circularly polarized wave with two orthogonal degenerate modes at 4.12 GHz with 3-dB axial ratio bandwidth of 17.69%. Further, the axial ratio bandwidth is increased to 21.81% by loading a rotated SRR on the slot. The split gap of the inner ring of SRR is rotated 90° with respect to outer ring gives circular polarization (CP) at 4.62 GHz. The wideband CP performance is achieved by the combination of truncated corner slot and rotated SRR mode resonances. Both bands are tuned independently to optimize the wide axial ratio bandwidth. The designed antenna is fabricated, and its performance is verified experimentally. The measured impedance bandwidth of 2.53 GHz (61.40%) and axial ratio bandwidth of 0.9 GHz (21.68%) with a peak gain of 2.74 dB is observed. The proposed wideband CP antenna is utilized for soil moisture sensing application and high sensitive microwave sensing application. © 2020Item Characteristic mode-based compact circularly polarized metasurface antenna for in-band RCS reduction(Cambridge University Press Journals_subscriptions@cup.cam.ac.uk, 2020) Tharehalli Rajanna, P.K.; Rudramuni, K.; Kandasamy, K.This paper presents a novel design of a low profile circularly polarized (CP) metasurface (MTS) antenna with in-band radar cross-section (RCS) reduction property. The MTS is loaded as a superstrate on slot antenna and it can be viewed as a polarization-dependent MTS (PDMTS). The rectangular patch-based PDMTS is analyzed using characteristic mode analysis to find two orthogonal degenerate modes, which produces CP waves. Linearly polarized slot antenna is used to excite the PDMTS. The performance of PDMTS loaded slot antenna is analyzed numerically using full-wave analysis method. The PDMTS CP antenna is fabricated and its performance is tested experimentally. The proposed antenna has a compact structure and it has an overall size of (where is the free space wavelength). The measured results show that the PDMTS antenna achieves impedance bandwidth of 29.41, 3-dB axial ratio bandwidth of 9.05, broadside gain of 6.34 dB, and monostatic RCS reduction of at the resonant frequency of 5.86 GHz. The simulated results are in well agreement with the measured results and it is well suited for C-band Radar and Satellite communication. © © Cambridge University Press and the European Microwave Association 2019.Item Slot coupled dual band high gain circularly polarized metasurface antenna(John Wiley and Sons Inc, 2022) Tharehalli Rajanna, P.K.; Rudramuni, K.; Kandasamy, K.This article presents a slot coupled dual-band metasurface (MTS) based antenna with high gain and circular polarization characteristics. The MTS consists of two different unit cells, which give rise to two operating bands. The metasurface is excited by the slot aperture fed by a 50 Ω microstrip feed-line. The circular polarization is achieved by the diagonally oriented rectangular patch-based unit cells on top of the square substrate. Two orthogonal modes of MTS are required to produce circularly polarized waves, and these modes are excited by the slot aperture. The proposed MTS-inspired antenna is fabricated and experimentally validated. The experimentally verified impedance bandwidth of 33.71% in the lower frequency band and 5.35% in the upper-frequency band is achieved. The measured 3 dB (AR <3 dB)axial ratio bandwidth of 6.22% and 0.98% with a peak gain of 8.89 and 6.32 dBic is achieved with respect to 4.8 and 6.4 GHz resonant frequencies. © 2022 Wiley Periodicals LLC.