Faculty Publications
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Publications by NITK Faculty
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Item Compact bandpass filter based on hybrid spoof surface plasmon and substrate integrated waveguide transmission line(Institute of Electrical and Electronics Engineers Inc., 2017) Rudramuni, K.; Kandasamy, K.; Kandwal, A.; Zhang, Q.In this paper, spoof surface plasmon polariton (SSPPs) and substrate integrated waveguide (SIW) based bandpass filter is proposed. The metal strip on the top of the substrate is composed of periodic slots which supports surface wave mode of SPP within the closed substrate integrated waveguide. The dispersion relation of the proposed structure shows that it has both low-pass feature of SSP and the high-pass feature of SIW, and hence the combination of these two features leads to a bandpass filter (BPF). The results show that the passband is from 11.5-19 GHz with relative bandwidth of 49%. Bandwidth can be controlled by properly adjusting the parameters of the design. The proposed design features a compact size and easy fabrication, due to the integration of SPP in a closed SIW. © 2017 IEEE.Item A Wideband Circularly Polarized Slot Antenna Backed by a Frequency Selective Surface(Korean Institute of Electromagnetic Engineering and Science, 2019) Kumar, P.; Tharehalli Rajanna, P.K.T.; Rudramuni, K.; Kandasamy, K.This paper presents the design of a coplanar waveguide (CPW)-fed single-layer wideband circularly polarized (CP) planar slot antenna backed by a frequency selective surface (FSS). The planar slot antenna is fed with a stub-loaded modified CPW feed line to tune and optimize the impedance bandwidth. The corners of the square slot antenna are perturbed to produce two orthogonal degenerate modes required for a wideband CP operation. The FSS layer is placed under the slot antenna to increase the gain and axial ratio bandwidth. The measured results of the proposed antenna provide an impedance bandwidth of 63.22% and an axial ratio bandwidth of 31.14% with a peak gain of 4.87 dB. The proposed antenna has a simple geometry, a wide CP bandwidth, and a good gain. © 2019. The Korean Institute of Electromagnetic Engineering and Science. All Rights Reserved.Item A High-Gain Circularly Polarized Antenna Using Zero-Index Metamaterial(Institute of Electrical and Electronics Engineers Inc., 2019) Tharehalli Rajanna, P.K.T.; Rudramuni, K.; Kandasamy, K.In this letter, a novel high-gain circularly polarized (CP) antenna based on the zero-index metamaterial (ZIM) is presented. A square ring with two asymmetrical splits is used as a unit cell to achieve high gain and circular polarization. The 9 × 9 periodic array unit cells act as an aperture efficient focusing metasurface lens and polarization converter for a primary source antenna. The focusing effect of the ZIM enhances the gain of the microstrip patch antenna placed above it by an amount of 5-6 dB. Also, the ZIM converts the linearly polarized wave emitted by the patch antenna into circularly polarized waves. The circular polarization is achieved by optimizing the two split gaps on the ring of the unit cell, which gives two orthogonal polarizations with the required phase. The proposed design is fabricated and verified experimentally. The prototype has measured impedance bandwidth from 7.04 to 7.68 GHz. The 3 dB axial ratio is achieved from 7.11 to 7.56 GHz, with a peak gain of 12.31 dBic at 7.45 GHz. The gain of around 11.5 dBic is achieved over the entire CP bandwidth with a good cross-polarization level. © 2002-2011 IEEE.Item Compact triband circularly polarized planar slot antenna loaded with split ring resonators(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2019) Tharehalli Rajanna, P.K.T.; Rudramuni, K.; Kandasamy, K.In this article, a coplanar waveguide (CPW) fed triband circularly polarized (CP) planar slot antenna loaded with split ring resonators (SRRs) is presented. The truncated slot antenna resonates at 4.15 GHz, which gives two orthogonal degenerate modes to produce circular polarization at the first band. The second and third band resonances are achieved at 4.77 GHz and 5.1 GHz respectively due to the loading of SRRs on the slot antenna. The electric fields produced by the single and multiple split gaps in each ring of SRR1 and SRR2 produce CP at the second and third band. All three bands are tuned independently to achieve optimized axial ratio bandwidth. The antenna is fabricated and verified experimentally. The measured results give impedance bandwidth of 64.54% and axial ratio bandwidths of 11.76%, 1.9%, and 3.87% at first, second, and third band, respectively. © 2019 Wiley Periodicals, Inc.Item Goubau line based end-fire antenna(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2019) Rudramuni, K.; Tharehalli Rajanna, P.K.T.; Kandaswamy, K.; Majumder, B.; Zhang, Q.This article proposes a simple and low profile planar Goubau line based end-fire antenna. End-fire radiation is achieved by modifying the Goubau line into inverted periodic arrangement of V-shaped unit cells. Designed prototype is simulated and verified experimentally. Both the simulated and measured results are in good agreement. Proposed antenna radiates toward end-fire direction between 7.8 and 8.3 GHz. The maximum gain of the antenna is obtained around 7.2 dBi. The average efficiency is observed 70% over the entire operating bandwidth. Proposed end-fire antenna has a single metallic layer with simple configuration which is easy to fabricate and also easy to integrate with other electronics circuits. The proposed antenna can be used for satellite and RADAR applications. © 2019 Wiley Periodicals, Inc.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 Dual-band dual-polarized leaky-wave structure with forward and backward beam scanning for circular polarization-flexible antenna application(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2020) Rudramuni, K.; Majumder, B.; Kandasamy, K.In this paper, a novel dual-band dual-polarized leaky-wave antenna (LWA) with polarization diversity is proposed using half mode substrate-integrated waveguide (HMSIW)-based technology. HMSIW LWAs are generally single band. In this work, by etching simple spiral type slots on the HMSIW cavity, a novel dual-band dual-polarized LWA is designed. The proposed antenna resonates at 5.6 and 8.5 GHz. Moreover, the antenna radiates the linearly polarized wave in the lower band and circularly polarized (CP) wave in the higher operating band. Also, in the higher operating band between 8.7 and 9.3 GHz, the proposed overall antenna exhibits both right-hand circular polarization as well as the left-hand circular polarization in the near main beam direction. The ?10 dB impedance bandwidth of the proposed antenna at the lower and the higher operating bands are 27% (4.86-6.4 GHz) and 25% (7.4-9.6 GHz), respectively. In the higher band, the 3-dB axial ratio bandwidth of 6.6% (8.7-9.3 GHz) is achieved. The main beam of the antenna can be steered from 19° to 69° in the forward direction in the lower operating band. In the higher operating band, the antenna can steer the CP beam between ?17° and ?32°. In both the lower bands, the realized peak gain is observed around 13.3 dBi, whereas in the higher band, the realized peak gain is observed around 14 dBi. © 2020 Wiley Periodicals, Inc.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.