Cancellation of Beam Squint with Frequency in Serial Beamforming Network-Fed Linear Array Antennas

This communication investigates the capability of serial beamforming networks to cancel beam squint with frequency in linear array applications. Such a property could be of interest for broadband applications with multiple narrow beams. The theoretical aspects are described, as well as the impact on the beamforming network design. It is found that the main limitation to achieving beam-squint cancellation in serial beamforming networks comes from the insertion phase of the different directional couplers needed. A specific design at S band with a single-beam four-element linear array is detailed. Experimental validation in microstrip technology is presented, confirming the cancellation of beam squint with frequency over a 9% bandwidth. The design of the elementary directional couplers is the main limitation in terms of frequency bandwidth. The applicability of such a design procedure to serial multiple beamforming networks, namely Blass and Nolen matrices, is discussed.