Circularly Polarized Planar Aperture Antenna for Millimeter-Wave Applications

This paper presents a novel differentially driven planar aperture antenna with circularly polarized (CP) radiation. The proposed antenna is simple in structure yet can achieve high gain and wide bandwidth, and is constructed using only a single layer laminate via standard printed-circuit-board (PCB) technology. Circular polarization is realized by a rotationally symmetric windmill-shaped patch-aperture formation with travelling wave distribution. The physical aperture of the antenna is constituted by an opening cavity structure formed by metalized vias, which offers high-gain unidirectional radiation pattern. Measurement results of a prototype operating at 60 GHz band show a 3-dB axial ratio (AR) bandwidth of 17.9% (56.5-67.5 GHz), which is within its -10-dB impedance bandwidth. Meanwhile, the left-handed CP (LHCP) gain is stable throughout the operating bandwidth with a peak gain of 13.4 dBi. The proposed antenna is a promising candidate for various consumer level millimeter-wave (mmWave) band applications due to its merits of wideband, high gain, simple structure, low cost, and easy integration with differential circuits.