Phase-controlled beamforming network intended for conformal arrays

This work describes a reconfigurable 1 × 4 network able to provide beamforming capabilities to conformal antenna arrays. In particular, the proposed feed network is able to activate either single output ports or couples of adjacent output ports of a four-element array. The output-port selection is achieved by controlling only the phase of four variable phase shifters. In the case where two output ports are activated, the network is also able to control the phase relationship between the signals, enabling in-phase and 180°-out-of-phase signal configurations. To test the developed theory, a prototype in microstrip technology, designed to operate in the recently released sub-6 GHz 5G 3.4 GHz to 3.8 GHz band, was manufactured, confirming adequate behavior of the network. The proposed circuit was then connected to a four-element antenna cube where it was used to generate twelve different beams: eight equally-spaced beams over 360° with maximum gain in their broadside direction, which enabled a uniform coverage of the azimuthal plane, and four equally-spaced beams with nulls in their broadside direction, useful in applications such as interference removal and radio localization.