A patch-resonator-based Butler Matrix with new triangular phase shifters

In this paper, a new novel patch based Butler Matrix using 3-dB square-patch coupler and triangular-patch wideband phase shifter is presented. By inserting a via hole along the symmetrical plane of the triangular patch, the bandwidth of the transmitting response is significantly increased. In order to obtain a 45° phase difference and a wideband phase response, a reference line with high characteristic impedance is applied and the length of the feeding line for the triangular-patch structure is adjusted correspondingly. As an application, a patch-based Butler Matrix is designed and fabricated around 4 GHz. The measured patch-based Butler Matrix shows a good agreement with the simulated results. 18% bandwidth is obtained with the return loss better than -10 dB.