Beamforming Approach for Steerable Null Synthesis in a Four-Element Conformal Array fed with a Radio-Frequency Reconfigurable Network

This paper presents a beamforming network used to synthesize steerable nulls. The antenna topology consists of four patch antennas placed on the lateral sides of a cube. From the analysis of the array factor and the radiation pattern of the single radiating elements, the theory to realize fully steerable nulls on the azimuth plane is presented. The array, targeted for an operating frequency of 3.6 GHz, is fed by a reconfigurable radio-frequency network. The network, which bases its reconfigurability on eight phase shifters, makes it possible to excite couples of adjacent output ports with arbitrary amplitudes and phases. The radiation pattern of the topology is measured for different excitations, confirming the theory. This approach opens the way to a new beamforming approach, that can be applied to interference removal and radio localization applications.