A Wide-Angle Scanning Phased Array Antenna with Non-Reciprocal Butler Matrix Beamforming Network

The theory and design of a wide scan array antenna is presented in this paper. A conventional 4x4 butler matrix is used to achieve four fundamental beam arrays from -45 degrees to + 45 degrees. The use of Butler Matrix relaxes the requirement of the progressive phase and consequently the phase shifters to a good degree. The butler matrix is also integrated into a non-reciprocal feed network structure to achieve a non-reciprocal beamforming network with less complexity of the phase shifter and resolution requirements. The non-reciprocity is achieved through unidirectional amplifiers, different phase shifters with opposite progressive phases as well as a good Wilkinson power divider for isolation between the TX and RX paths. Two different progressive phases are also designed and shown here for the proof of concept. With one SP4T switch, and two passive low and high pass filters, eight different beam patterns were achieved four of them are for the transmit and the other four are for the receive paths. Any combination of the TX and RX paths can be used for different applications with a full-duplex scheme.