60-GHz Polarization-Adjustable Antenna Arrays

This paper proposes 2 × 2 and 4 × 4 polarization-adjustable millimeter-wave antenna arrays. The antennas were designed to function at 60 GHz and are planar and vialess. The proposed antenna designs contain two input ports; if the input phases and magnitudes of the two input ports can be controlled, enabling the proposed antenna to generate six types of polarization: right-handed circular polarization, left-handed circular polarization, and linear polarization along the φ = 0°, φ = 45°, φ = 90°, and φ = 135° axes. The achieved antenna gain of the 2 × 2 polarization diversity array was approximately 12 dBi, whereas that of the 4 × 4 array was 16 dBi. Prototypes of both the 2 × 2 and 4 × 4 arrays were fabricated and tested. The operating mechanism and design steps are described in detail in this paper.