Feedforward embedding circulator enhancement in transmit/receive applications

In this work, a feedforward embedding technique is presented to improve the isolation of a circulator. The circuit configuration is particularly suitable for transmit/receive applications where the received signal is extremely weak compared to the transmitted signal and where a mismatch at the antenna may exist. It is demonstrated that the isolation of a circulator can be improved by an additional 30 dB by using a feedforward embedding method. Test performance of a commercial 1-GHz circulator with and without the feedforward network is shown.