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 An Autonomous Frequency Reconfigurable Antenna Using Slotline Open-Loop Resonators(Institute of Electrical and Electronics Engineers Inc., 2021) Polaiah, G.; Kandasamy, K.; Kulkarni, M.This paper presents a slotline open-loop resonators based frequency reconfigurable antenna with autonomous switching of frequency bands. The dual-port slot antenna is designed to operate at 2.1 GHz when excited at port-1, and when port-2 is excited, the antenna can be reconfigured to operate at 2.85 GHz and 5.52 GHz, respectively. Port-1 is used to receive the control signal, which is converted to a DC signal using a rectifier. The rectified control signal is used to switch the operating frequency bands of the port-2. The proposed antenna configuration gives the flexibility of remote/wireless control of the operating frequency. The antenna prototype is fabricated and measured for observing the frequency switching at port-2. The measured results show that the antenna has been effectively switched from lower band frequency (2.8 GHz) to upper band frequency (5.41 GHz) when the PIN diode is ON. The proposed antenna in its final configuration can be potentially suitable for transmitter reconfigurable antenna without the need for external DC bias voltage. © 2021 Institute of Electrical and Electronics Engineers Inc.. 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.