Transmit-receive isolation in phased array antennas for duplex communication systems

In this paper we identify the generic coupling mechanism between transmit and receive channels in phased array antennas providing full duplex communication links to multiple users. The transmitter-to-receiver coupling degrades the receive S/N and produces unwanted spurious signals in the receive band. Both effects can be reduced to sufficiently low level by increasing isolation between the transmit and receive channels using filters on the transmit as well as on the receive side. We developed a procedure to analyze the coupling effects and to determine the necessary filter characteristics for a typical T/R module configuration and array architecture.