Millimeter Wave Switched Beam Rectangular Loop Dipole Antenna Array Using a 4×4 Butler Matrix

Abstract

A four-stage switched beam antenna array at millimeter-wave (mm-wave) frequencies is designed, fabricated, and experimental results are demonstrated. A novel rectangular loop dipole antenna (RLDA) applying the quasi Yagi-Uda concept is designed to achieve high gain and wide bandwidth with end-fire radiation. This RLDA with director has a return loss better than 10 dB over a frequency range of 32 GHz to 37 GHz and a peak gain of 8.5 dB. The proposed high gain end-fire RLDA antenna in combination with a 4 × 4 Butler Matrix (BM) creates the switched beam configuration and generates four beams in the directions of 15and −15 • ± 1 • at 33.5 GHz, 34.5 GHz, and 35.5 GHz with successive input port excitation. The switched beam configuration has overall dimensions at 34.5 GHz is 26 mm × 25.8 mm (3.03λ × 3.0λ).