Abstract
In this paper, a novel 3\times 3 Nolen matrix based on trans-directional (TRD) coupled lines is proposed for beam-forming antenna array applications. The proposed Nolen matrix consists of a 4.78-dB coupler, two 3-dB couplers, two 3\lambda/4 transmission lines, and a \lambda/2 transmission line. The 4.78- and 3-dB couplers are realized by using TRD coupled lines. By exciting one of three input ports, the proposed 3\times 3 Nolen matrix generates three equal magnitude outputs, and three progressive phase shifts at its three output ports, which are 0°, 120°, and -120°, respectively. To validate the proposed concept, a prototype of the proposed Nolen matrix operating at 3.5 GHz is designed, fabricated, and measured. The simulated and measured results are in good agreement.