Single Layer, Differentially Driven, LHCP Antenna With Improved Isolation for Full Duplex Wireless Applications

Haq Nawaz,Ahmad Umar Niazi,Muhammad Usman,Muhammad Abdul Basit

doi:10.1109/access.2019.2954947

Abstract

This paper presents a unidirectional, left handed circularly polarized (LHCP), single layered antenna array with improved interport isolation for simultaneous transmit and receive (STAR) or in-band full duplex (IBFD) wireless applications. The proposed IBFD antenna is comprised of three identical and sequentially rotated LHCP radiating elements where two Rx patches are symmetrically placed with respect to a single Tx patch. The symmetry of proposed antenna structure results in same amount of coupling or self interference (SI) from Tx element and differentially driven Rx patches achieve effective suppression of resulting SI to obtain improved Tx-Rx interport isolation required for STAR applications. The deployed feed network for differential-driven Rx operation is composed of a simple 3dB/180° rat-race coupler (ring hybrid coupler) with nice in-band amplitude and out-of-phase balance characteristics. The implemented single layer, compact (antenna elements and feeding network etched on single-layered PCB) antenna array achieves 10dB return-loss bandwidth ≥ 75MHz for both Tx and Rx ports. The prototype achieves ≥ 47dB interport isolation in 75MHz bandwidth and 3 dB axial ratio beam-width is ~ 60° for implemented antenna.

Highlights

The superior spectral efficiency is a key factor to offer higher data rates or throughputs in generation wireless networks [1], [2]
We have employed a 3dB/180◦ ring hybrid coupler having nice amplitude and out-of-phase phase balance responses to differentially drive the Rx patches to achieve improved self interference cancellation (SIC) levels for presented in-band full duplex (IBFD) antenna array with left handed circularly polarized (LHCP) characteristics for both Tx and Rx modes
EXPERIMENTAL RESULTS FOR IMPLEMENTED COMPACT LHCP ANTENNA ARRAY For experimental validation and performance evaluation, a prototype of compact LHCP antenna array was implemented on 1.6mm thick single-layered FR-4 substrate

Summary

Introduction

The superior spectral efficiency (bps/Hz) is a key factor to offer higher data rates or throughputs in generation wireless networks [1], [2]. IBFD transceivers find a major application in electronic warfare systems to offer the possibility of simultaneous jamming and monitoring of radio signals in required bandwidth. Practical realization of IBFD operation [5] This strong in-band coupling acts as a jamming signal for very weak received signal of interest (SOI) to severely degrade the signal to noise ratio (SNR) [7]. Such type of SI results from direct coupling between Tx and Rx chains (composed of both linear and non-linear components) in addition to SI caused by reflections of Tx signals from nearby objects) [8]

Methods

Results

Conclusion