Circularly-polarized Antenna Arrays in Package with Rotated Sequential Feeding Network for Millimeterwave Communications

This paper proposes rotated sequential feeding network for circularly-polarized antenna arrays in package to achieve broad 3-dB axial ratio bandwidth. The proposed antenna consists of multiple layers containing radiating patches, quadrature feed, rotated sequential feed, and power supply lines. This multilayer feeding network allows for exciting balanced 90° phase difference to the circular patch antennas with a phase error less than 5° in the target bandwidth. Consequently, the axial ratio bandwidth is improved from 7.1% to 75%, compared to the conventional feeding mechanism. Furthermore, the axial ratio characteristics remain stable for the beam steering operation within the range of θ
0
≤ 60°.