Linearly Co-Polarized Dual Band In-band Full-Duplex Antenna System with Defected Ground Structure

This paper presents a compact, linearly co-polarized in-band full duplex (IBFD) antenna system that operates in two distinct frequency bands of the sub-6 GHz spectrum. It consists of two identical microstrip patch antennas (MPAs) along with defected ground structures (DGSs) on a single-layer printed circuit board (PCB). The quarter-wavelength long MPAs along with the DGSs in the ground plane facilitates the dual-band characteristics of the proposed antenna system. The quarter-wavelength MPAs are obtained by short-circuiting one of the radiating edges by an array of metallic vias. The designed antenna system operates in TM<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</inf>,<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> mode at 2.4 GHz, with |S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>| ⩽ -10 dB bandwidth of 2% and a gain of 4.35 dBi. At 5.2 GHz, it operates in TM<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/2</inf>,<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> mode, with |S<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</inf>| ⩽ -10 dB bandwidth of 6.8% and a gain of 4.82 dBi. The good impedance characteristics and good inter-port isolations at both the operating frequencies makes the designed antenna system a potential candidate for IBFD systems.