A Highly Isolated IN-Band Full Duplex Antenna Using Defected Ground Structure and Parasitic Strips

In this communication, a highly isolated, low crosspolarized two-port antenna system using defected ground structure (DGS) and parasitic strips (PS) at 5.85 GHz is proposed. The combination of DGS and PS gives isolation (> 93 dB) exactly at the center frequency of impedance bandwidth, which can facilitate self-interference cancellation in the context of full-duplex (FD), without the need for extra circuitry. The individual antennas in the FD antenna exhibit a fractional bandwidth of 3.9% and a realized gain of 6.27 dBi with 97% efficiency. The proposed FD antenna system has two radiating elements with an overall dimension and edge-to-edge spacing of 0.97λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> × 0.68λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> × 0.03λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> and 0.14λ<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> respectively. The simple planar design and feeding mechanism make it easy to fabricate and practical for use in full duplex systems.