Simple Blass Matrix Design Strategy for Multi-Beam Arbitrary Linear Antenna Arrays

Multi-beam antenna arrays are currently recognized as one of the enabling technologies for the next generation communication standards. One of the key components of these systems is the beamforming network that implements the array element excitations. This paper addresses this issue by presenting a novel strategy to realize an analog feeding network, which allows an arbitrary linear array (LA) to radiate multiple arbitrary beams. In particular, an iterative procedure is conceived to design a Blass matrix using an identical directional coupler for all nodes, resulting in a very simple structure suitable for large-scale production. Two applications with arbitrary directions are illustrated as proofs-of-concept for the developed architecture: a dual-beam configuration with a null involving an aperiodic LA, and a four-beam configuration involving a periodic LA. For this second application, the effectiveness of the proposed solution is further verified by full-wave simulations and experimental measurements carried out on a fabricated prototype.