A Low-Profile Unidirectional Printed Antenna for Millimeter-Wave Applications

By combining a printed reflector-backed one-wave-length bowtie antenna and a printed double loop antenna, a new wideband high-gain antenna element is demonstrated. Due to its low-profile structure of ~ 0.05λ0, it is attractive to be used in an array environment. Experimentally, a series of antenna arrays operated at 60 GHz are designed and fabricated. They achieve wide impedance bandwidths covering the 57-64 GHz unlicensed frequency band. Over this band, the measured antenna gains are ranged from 14.5-15.5 dBi, 18.3-20.1 dBi and 22.5-25.2 dBi for 4-element, 14-element and 50-element antenna arrays, respectively. The measured radiation pattern has low cross-polarization level and low back radiation. The proposed low-profile antenna and arrays are low-cost in fabrication as they are simply made on a single-layer printed circuit board.