A Novel Planar Nolen Matrix Phased Array for MIMO Applications

Abstract

In this paper, a novel Nolen matrix phased array for MIMO applications is presented. The proposed $4\\times 4$ Nolen feeding network consists of six couplers and eight phase shifters in a triangular lattice. Each coupler represents a node in the lattice, and each phase shifter connects two adjacent couplers. By exciting one of four input ports, the proposed $4\\times 4$ Nolen matrix generates four unique phase differences at its output ports, which are 0°, +180°, +90°, and −90°, respectively. By intergrading with radiating elements, the corresponding four radiation beams are achieved in desired direction. The closed-form equations are derived for the proposed Nolen matrix with flexible structure. To verify the proposed design concept, a $4\\times 4$ Nolen matrix operating at 5.8 GHz is designed, fabricated and measured, and the simulation and measurement results agree well with each other to prove the design theory.