A Compact Four-Port Coplanar Antenna Based on an Excitation Switching Reconfigurable Mechanism for Cognitive Radio Applications

• Published in: Applied sciences Vol. 9; no. 15; p. 3157
• Main Authors: O, Yeonjeong, Jin, Yunnan, Choi, Jaehoon
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.08.2019
• Subjects: Antennas; Cognitive radio; cognitive radio (CR); Communication; Coplanar waveguides; Design; Fabrication; Ground plane; Interaction parameters; isolation; narrowband (NB) antenna; Radiation; Radios; Resonant frequencies; Spectrum allocation; spectrum sensing; Systems design; ultra-wideband (UWB); Ultrawideband
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app9153157

In this paper, we propose a compact four-port coplanar antenna for cognitive radio applications. The proposed antenna consists of a coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna and three inner rectangular loop antennas. The dimensions of the proposed antenna are 42 mm × 50 mm × 0.8 mm. The UWB antenna is used for spectrum sensing and fully covers the UWB spectrum of 3.1–10.6 GHz. The three loop antennas cover the UWB frequency band partially for communication purposes. The first loop antenna for the low frequency range operates from 2.96 GHz to 5.38 GHz. The second loop antenna is in charge of the mid band from 5.31 GHz to 8.62 GHz. The third antenna operates from 8.48 GHz to 11.02 GHz, which is the high-frequency range. A high isolation level (greater than 17.3 dB) is realized among the UWB antenna and three loop antennas without applying any additional decoupling structures. The realized gains of the UWB antenna and three loop antennas are greater than 2.7 dBi and 1.38 dBi, respectively.