Adaptively Thinned Arrays

Array thinning places a low sidelobe amplitude taper on a large antenna array by making certain elements in a uniform array inactive. The active elements contribute to forming the beam, while the inactive elements are terminated in a matched load. Transmit/receive (T/R) modules often have switches that not only connect to the transmit or receive paths but also connect to a calibration port. In addition to changing between transmit, receive, and calibration modes, these switches can be used to alter the array thinning to either modify the sidelobe level or move a null. This paper describes an approach to interference suppression by adaptively thinning the array in order to reject sidelobe interference. Changing the random thinning can lower a sidelobe or place a null in the direction of interference.