Directional notch filter for simultaneous transmit and receive of wideband signals

A directional notch filter for simultaneous transmit and receive of wideband signals, the directional notch filter comprising:

• a first directional coupler and a second directional coupler for receiving from an antenna, an input signal comprising a reflection of a high-power broadband transmit signal spectrally overlapping with a low-power narrow band or broadband desired received signal, wherein the first and second directional couplers are configured to produce respective first and second signals comprising portions of the received input signal, while respective first and second terminations at isolation ports of the first and second directional couplers prevent multiple reflections within the first and second signals;
• a shaping filter for receiving the second signal from the second directional coupler, wherein the shaping filter is configured to produce a compensation signal as a replica of an antenna reflection transfer function, wherein the shaping filter creates a notch in the reflected transmit signal;
• a delay compensator for receiving the first signal and matching the path delay of the first signal to the second signal and outputting a delayed first signal;
• and
• a power combiner configured to receive as inputs, the compensation signal and the delayed first signal, and to subtract the compensation signal from the delayed first signal to cancel self-interference and provide a combined output as an input to a receiver.