Filter design methods applied to panelized antenna array integration for digital backends

Digital arrays offer much greater flexibility at a lower cost than traditional analog arrays. A digital array need not be fixed to a single purpose, but can be designed to be capable of performing multiple functions at once.;As much of a digital array's functionality is implemented in software, the RF frontend can be quite simple relative to traditional analog arrays. This fact, along with recent advances in solid state technology makes it possible to integrate the RF frontend, including antennas, into a single panel using standard multilayer board manufacturing techniques, as will be demonstrated herein. To further improve this integration, a technique will be demonstrated in which antennas and filters can be designed as a single unit using traditional filter design techniques.;Furthermore, these design techniques are extended to multiple antenna systems by enabling simultaneous transmit and receive. Systems designed for simultaneous transmit and receive must implement new techniques in the RF hardware to isolate the receive paths from the high-power transmit signals. The use of tunable resonators at the antenna panel allows deep isolation to be achieved. The largest source of transmit to receive coupling in an array is due to coupling between antenna elements, which can be controlled through active baffle design viewed as a portion of a larger filtering system. Proposed and demonstrated herein are two distinct techniques to ensure high isolation between antenna elements using baffles consisting of tunable filter elements. These techniques improve isolation by over 50 dB, making simultaneous transmit and receive feasible.