Faculty Publications
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Publications by NITK Faculty
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Item A triband circularly polarized strip and SRR-loaded slot antenna(Institute of Electrical and Electronics Engineers Inc., 2018) Paul, P.M.; Kandasamy, K.; Sharawi, M.S.In this communication, a simple and compact multiband circularly polarized (CP) slot antenna loaded with metallic strips and a split-ring resonator (SRR) is proposed. The multiband operation is obtained via exciting the SRR and copper strips by the microstrip-fed square slot antenna. The SRR resonates at 1.83 GHz, while the strips and the slot antenna provide resonances at 2.5 and 3.1 GHz. Resonant modes of loaded SRR and strips combined with the fundamental mode of the slot produce CP waves at the resonance frequencies of the proposed antenna. The proposed antenna allows for independent tuning of different bands via the use of the tilted strips and the SRR. Also, the sense of polarization at the resonance frequencies can be controlled by changing the orientation of the strips and the SRR with respect to the slot. The proposed antenna is fabricated on an FR-4 substrate of dimension 50 × 50 × 1.56 mm3. Antenna performances in terms of 10 dB return loss bandwidth, 3 dB axial ratio bandwidth, gain, and efficiency are validated experimentally and are in a good agreement with the simulated results. © 2018 IEEE.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 A corner expanded slot antenna loaded with copper strips for dual-band circular polarization characteristics(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2020) Paul, P.M.; Kandasamy, K.; Sharawi, M.S.In this article, the design and implementation of a dual-band circularly polarized (CP) microstrip line fed square slot antenna with compact size is proposed. The proposed CP antenna consists of a square slot antenna with a pair of symmetric rectangular extensions on opposite corners and loaded with an array of inclined and truncated rectangular copper strips. The square slot with diagonal extensions resonates at 2.24 to 2.62 GHz with a 3 dB axial ratio (AR) bandwidth of 15.7%. Besides, loading it with an array of inclined and truncated rectangular copper strips helps produce a resonance at higher band with CP. The higher band operates between 3.26 and 5.18 GHz and centered at 4.52 GHz, with a 3 dB AR bandwidth of 45.5%. The polarization sense and resonant frequency of the proposed antenna can be independently tuned depending on the position and dimensions of the slot and strips, respectively. The proposed antenna is fabricated and measured in terms of impedance bandwidth, axial ratio bandwidth, peak gain, and radiation efficiency. Good agreement between the simulations and measurements of the prototype is obtained. © 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 Dual-Band Asymmetric Leaky-Wave Antennas for Circular Polarization and Simultaneous Dual Beam Scanning(Institute of Electrical and Electronics Engineers Inc., 2021) Rudramuni, R.; Majumder, B.; Tharehalli Rajanna, T.R.; Kandasamy, K.; Zhang, Q.In this article, two configurations of novel dual-band half-mode substrate integrated waveguide (HMSIW) leaky-wave antennas are presented. The first proposed antenna radiates linearly polarized (LP) waves in the lower band and circularly polarized waves in the upper band when the unit cells are cascaded sequentially. The second antenna, where the sidewall via of the HMSIW unit cells is connected alternatingly, provides simultaneous dual beams with different polarization in the upper operational band in addition to the LP beam in the lower operational band. The unit cells of the two antennas are analyzed in terms of their dispersion behaviors. Finally, the performance of both the antennas is experimentally verified. © 1963-2012 IEEE.Item Circularly polarized rectangular dielectric resonator antenna with elliptical aperture feed for 5 GHz ISM band(John Wiley and Sons Inc, 2021) Usha, L.; Kandasamy, K.In this article, a new elliptical slot aperture feed circularly polarized (CP) rectangular dielectric resonator antenna (RDRA) has been proposed. The nonresonant slot excites two spatially orthogonal resonant frequencies in RDRA to produce CP waves. TEx111 and TEy111 are the orthogonal modes produced by the 450 inclined elliptical slot with respect to microstrip feed. Also, the sense of polarization at the resonance frequencies can be controlled by changing the orientation of the slot. The antenna performances in terms of impedance bandwidth, 3-dB axial ratio, and gain are validated experimentally. The proposed antenna can be used in 5 GHz ISM band for WiFi/satellite communications. © 2021 Wiley Periodicals LLC.Item Linearly Polarized and Circularly Polarized Cylindrical Dielectric Resonator Antenna(Electromagnetics Academy, 2022) Usha, L.; Kandasamy, K.This paper presents the design of a novel aperture coupled cylindrical dielectric resonator antenna with linear polarization and circular polarization. The linearly polarized cylindrical dielectric resonator antenna (LP CDRA) with proposed aperture and microstrip feed line excites three hybrid radiating modes (HEM11δ, HEM21δ, and HEM13δ) in three impedance bands. The circularly polarized cylindrical dielectric resonator antenna (CP CDRA) with proposed aperture and flag-shaped feed line excites six different hybrid radiation modes (HEM11δ, HEM21δ-like, HEM21δ, HEM12δ, HEM13δ, HEM14δ) in three impedance bands and three CP bands. A different sense of CP is reported. The antennas operate in both C and X bands. © 2022, Electromagnetics Academy. All rights reserved.