High Isolation Novel Interleaved TRX Antenna Array with Defected Ground Structure for In-Band Full-Duplex Applications

Abstract

A compact symmetrical simultaneous transmit and receive antenna with high isolation is one of the main barriers that restricts the in-band full-duplex (IBFD) communication system architecture. To overcome this barrier, a novel interleaved transmit and receive antenna array with plus shaped defected ground structure (DGS) has been developed and presented in this paper. It is designed at 10 GHz, fabricated and validated with the measurements. The proposed interleaved array consists of symmetric 2x1 transmitter (TX) antenna elements and symmetric 2x1 receiver (RX) antenna elements with the spacing of 1λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> while the spacing between TX and RX (TRX) antenna elements is 0.5λ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> similar to a checkerboard pattern. The plus-shaped DGS is applied to reduce self interference (SI) by suppressing the existing surface wave between the TRX antenna elements. The measurement results confirm that this technique increased the isolation from 16.5 dB to 56.5 dB between TRX antenna arrays. In addition, the proposed array and a co-located array without DGS are compared in terms of simulation and measurement to present the benefits of the proposed antenna array. Furthermore, the interleaved antenna arrays with and without DGS are investigated to analyze the isolation characteristics. The analyses indicate that interleaved antenna array structure with DGS enhances the compactness and enables the alternative placement of TX and RX array antennas for better front-end designs towards in-band full-duplex (IBFD) communication systems for 5G and beyond. Simulation and measurement results confirm a close agreement for the proposed antenna array.