An improved self‐interference canceller for X‐band radar transceivers

Abstract

A study and analysis of an X-band transceiver self-interference cancelation system based on wideband 90°phase-shifters are presented. The analysis introduces the conditions for perfect isolation and imbalance mitigation in the system. A high isolation, low path-loss transmitter leakage canceller for single antenna frequency-modulated continuous wave radar applications is developed and fabricated to validate the provided analysis. The canceller consists of two circulators, three Wilkinson combiners/dividers and three phase-shifters. Practically, similar circulators have certain performance mismatches, which degrades conventional canceller performance. The proposed system uses a 90°phaseshifter along with the Wilkinson to allow the tuning of the phase difference for each branch to compensate for circulators' mismatches. The proposed canceller is designed at a 10 GHz centre frequency. The measurement results show more than 40 dB isolation for 600 MHz bandwidth (9.6-10.2 GHz) with less than 1.7 and 1.4 dB transmitter and receiver path-losses, respectively. The good agreement between measurements and simulations verifies the proposed system as well as the proposed analysis.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.