Implementation of an X band leakage cancellation network for bandwidth improvement

In this paper, the implementation of an X band Tx-to-Rx leakage cancellation network to achieve bandwidth improvement and high isolation performance is presented. The circuit architecture and leakage cancellation theory are described in detail. The operation principle of leakage cancellation network is based on phase cancellation technique. This architecture is made up of three two-section Wilkinson power dividers and a hybrid-ring, which miniaturizes the leakage cancellation network, compared with conventional ferrite circulators. The proposed architecture has been completely implemented and measurements have been carried out for verification. The simulated bandwidth is presented with 83% fractional bandwidth above 30dB isolation, and the corresponding measured fractional bandwidth is 31.2%. Meanwhile, the simulated bandwidth is presented with 16% fractional bandwidth above 40dB isolation, and the corresponding measured fractional bandwidth is 6.4% The measured peak isolation is 46.2dB@9.361GHz. Although the measured fractional bandwidth is decreased, the high isolation bandwidth between Tx port and Rx port based on the circuit architecture proposed in this paper, is still enhanced, especially compared with other conventional high isolation networks.