Faculty Publications
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Publications by NITK Faculty
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Item An electronically switchable UWB to narrow band antenna for cognitive radio applications(John Wiley and Sons Inc. P.O.Box 18667 Newark NJ 07191-8667, 2020) Jacob, N.; Kulkarni, M.; Kandasamy, K.Cognitive radio (CR) is designed to achieve intelligent spectrum sensing and sharing, in order to solve spectrum underutilization problem. Conventional CR uses multiple/multiport antenna to switch between UWB and narrow band (NB) frequencies for primary and secondary users. In this article, we propose a compact frequency reconfigurable single port antenna using PIN diodes, to switch between UWB and NB frequencies. A circular disc monopole antenna with partial ground plane is designed to deliver UWB response. Three interdigital capacitors (IDC) are electrically connected to a partial ground plane and feed line using PIN diodes. OFF condition of all PIN diodes will provide the UWB response of 2.8 to 10.6 GHz and ON condition of the diodes will result in 36 different NB frequencies, completely covering the UWB spectrum. A simulation study carried out by incorporating a varactor diode into IDC, clearly shows that, the antenna resonance can be switched using PIN diodes and each resonant frequency can be fine-tuned independently, with in the band of interest. This is the unique feature of proposed antenna, which facilitates the technology for CR based internet of things applications in 5G wireless communication networks. © 2020 Wiley Periodicals, Inc.Item Compact uwb slotted monopole antenna with diplexer for simultaneous microwave energy harvesting and data communication applications(Electromagnetics Academy, 2021) Polaiah, G.; Kandasamy, K.; Kulkarni, M.This paper proposes a new integration of compact ultra-wideband (UWB) slotted monopole antenna with a diplexer and rectifier for simultaneous energy harvesting and data communication applications. The antenna is composed of four symmetrical circularly slotted patches, a feed line, and a ground plane. A slotline open loop resonator based diplexer is implemented to separate the required signal from the antenna without extra matching circuit. A microwave rectifier based on the voltage doubler topology is designed for RF energy harvesting. The prototypes of the proposed antenna, diplexer, and rectifier are fabricated, measured, and compared with the simulation results. The measurement results show that the fractional impedance bandwidth of proposed UWB antenna reaches 149.7% (2.1 GHz–14.6 GHz); the diplexer minimum insertion losses (|S21 |, |S31 |) are 1.37 dB and 1.42 dB at passband frequencies; the output isolation (|S23 |) is better than 30 dB from 1 GHz to 5 GHz; and the peak RF-DC conversion efficiency of the rectifier is 32.8% at an input power of ?5dBm. The overall performance of the antenna with a diplexer and rectifier is also studied, and it is found that the proposed new configuration is suitable for simultaneous microwave energy harvesting and data communication applications. © 2021, Electromagnetics Academy. All rights reserved.Item Compact high-efficiency pentahedron and quatrefoil shape antennas with enhanced gain for GSM1800, 3G, 4G-LTE energy harvesting applications(Cambridge University Press, 2021) Polaiah, G.; Kandasamy, K.; Kulkarni, M.In this paper, three compact, high-efficiency, gain enhanced antennas, and corresponding rectifiers have been proposed for GSM1800, 3G, and 4G-LTE energy harvesting applications. The inverted L-stub is placed on the ground plane of the monopole antenna to get the desired frequency band of GSM1800 MHz. The feed length variation method has been adopted for the slot antennas to obtain the required frequency of 3G and 4G-LTE cellular bands. The performance of antennas is analyzed with the inverted L-stub, feed length variation, and the reflector distance. The maximum gain achieved with the reflector positioned at a distance of ?/4 from the antenna backside is three times greater than the gain obtained without the reflector. The prototype antennas and rectifiers have been simulated, fabricated, measured various parameters, and compared with the simulation results. The antennas provide more than 82% radiation efficiency and an enhanced gain of greater than 5.6 dB. The peak efficiency of rectifiers of more than 30% has been achieved. The aforementioned three antennas are integrated with their corresponding rectifiers for operating at 1.8, 2.1, and 2.3 GHz frequencies. The proposed rectennas are formidably suitable for the reception of RF power from the cellular bands. © © Cambridge University Press and the European Microwave Association 2020.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.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.Item A Novel Single-Layered Dual-Wideband Circularly Polarized Asymmetric Slot Antenna for Wireless Applications(Electromagnetics Academy, 2024) Shankaraiah, P.H.; Shet, N.S.V.; Kandasamy, K.This work focuses on the design and implementation of a dual-wideband asymmetric square-shaped slot radiator with coplanar waveguide (CPW) feed for circular polarization (CP) characteristics. The proposed radiator has inward ground plane extensions in the form of square and rectangular strips on the diagonal corners of the slot. By optimizing the size of strips, a dual-band antenna with CP behaviour is obtained. The inverted L-shaped grounded strip improves axial ratio bandwidth (ARBW). The extended signal line terminated in a wide tuning stub significantly improves impedance bandwidth (IBW) and also further enhances ARBW. The designed asymmetric slot radiator is fabricated using an FR-4 substrate material of dimensions 50×50×1.6 mm3. This antenna design gives flexibility to alter polarization sense at the dual frequency bands. Further, edge effects are analyzed through electric field distribution, and their impact on impedance and AR characteristics are studied. It is designed, fabricated, and tested, and shows right-hand circular polarization (RHCP) response at 3 GHz and 7.5 GHz in the +Z direction. The experimentally verified results show −10-dB IBWs of 40.12% (range from 2.61 GHz to 3.92 GHz) and 40.21% (range from 6 GHz to 9.02 GHz), and 3-dB ARBWs are 20% (range from 2.70 GHz to 3.30 GHz) and 40.21% (range from 6 GHz to 9.02 GHz) at the resonance bands. The experimentally measured and simulated performance parameters of the prototype are in close agreement. The proposed perturbed slot radiator is well suited for Wi-Fi 6E communication and remote sensing applications. © 2024, Electromagnetics Academy. All rights reserved.Item Metamaterial based stepped microstrip line fed quad-band dual-sense circularly polarized slot antenna for wireless applications(Cambridge University Press, 2025) Shankaraiah, P.H.; Shet, N.S.V.; Kandasamy, K.This research proposes a low-complexity, low-profile square-shaped quad-band dual-sense circularly polarized (CP) perturbed slot antenna with stepped microstrip feed for C-band radar and satellite applications. The proposed antenna is characterized by characteristic mode analysis. The proposed design has a square-shaped slot with diagonally opposite symmetric rectangular corner extensions. Multiband resonance is achieved by exciting the split ring resonator (SRR), cross strips and annular ring structure using the stepped microstrip line-fed slot radiator. The slot antenna and a metallic ring resonate at 1.64 and 8.2 GHz, respectively, showing left-hand circular polarization response, whereas the SRR and cross strips resonate at 3.6 and 6.6 GHz, respectively, exhibiting right-hand circular polarization radiation at these resonance bands. Hence, the proposed design shows quad-band performance with dual-sense CP behavior. Furthermore, the proposed antenna allows for independent tuning of polarization sense at resonance frequencies. The proposed design uses a low-cost FR-4 material as a substrate of dimensions 60 × 60 × 1.6 mm3. The experimentally measured results are in close agreement with the simulated performance parameters of the prototype. © The Author(s), 2025. Published by Cambridge University Press in association with The European Microwave Association.