Coupled antenna scheme using filter design techniques and tunable resonators to show simultaneous transmit and receive

In order to enable multifunction arrays with simultaneous transmit and receive, high isolation must be provided between antenna elements. This isolation should ideally be independent of the waveforms being transmitted. In this paper, a tunable baffle design is presented which provides over 30 dB of improvement in isolation for bandwidths of 7.5 MHz between adjacent antennas. This isolation can be tuned in frequency to protect a given receive channel from transmitter interference. Filter approaches are used to analyze the antenna design and extract the interactions between each resonator. The antennas and the resonant baffles can be modeled as one coupling matrix just as in filter design approaches. This allows a notch filter to be created in which the direct coupling path between antenna patches is counteracted by the interaction of the resonators in the baffle.