Reconfigurable Generalized Joined Coupler Matrices for Independent Control of Multiple Steerable Beams

It is a widely recognized challenge to achieve independently steerable multiple beams using analog circuits. The generalized joined coupler (GJC) matrices have been proved capable of realizing multiple beams with flexible beam directions and low sidelobe levels (SLs). A major advantage of GJC matrix is that the phase shifters in each row are the same, thus facilitating easy and independent control of beams. In this article, for the first time, a reconfigurable GJC matrix as a multibeam feed network (MFN) is reported using planar circuits and verified experimentally. Beam steering is realized by a series of novel low-loss tunable reflection-type phase shifters (RTPSs), which are modeled and thoroughly analyzed. Based on the hybrid couplers and tunable phase shifters, a $2\times 8$ reconfigurable GJC matrix is modeled and simulated using planar microstrip lines, and prototype is fabricated and tested. Low loss, excellent matching and continuous tuning phases with the minimum phase error are obtained from simulation as well as measurements. Finally, the designed matrix is employed to feed a linear array for steering multiple beams. The realized beam patterns have successfully demonstrated that the designed reconfigurable GJC matrix is capable of independently controlling multiple beams simultaneously.