2-D Scanning Magnetoelectric Dipole Antenna Array Fed by RGW Butler Matrix

Abstract

In this paper, a 2-D scanning magnetoelectric (ME) dipole antenna array fed by printed ridge gap waveguide (PRGW) Butler matrix is proposed. The ME dipole antenna is designed to achieve a bandwidth wider than 20% at 30 GHz and stable gain of 6.5 ± 0.8 dB over the operating frequency bandwidth. A $4\times 4$ planar PRGW Butler matrix is designed and constructed using a four PRGW hybrid couplers having a wide bandwidth performance. The overall performance of the Butler matrix exhibits about 5° phase error over the operating frequency bandwidth. The integration of ME dipole antennas with the designed Butler matrix results in four fixed beams, one in each quadrant at an elevation angle of 35° from the broadside to the array axis. The proposed passive beam switching network (BSN) has a wide bandwidth of 20% with radiation efficiency higher than 84% over the operating bandwidth. The proposed BSN shows a stable radiation pattern with a stable gain of 10.3±0.2 dB, where the sidelobe level is less than −15 dB over the whole operating frequency band. The fabricated prototype of the proposed BSN is tested, where the measured and simulated results show an excellent agreement.