A Ku-Band Circularly Polarized Array Antenna Based on Vertical Virtual Ground

In this paper, a compact 2 × 2 wideband circularly polarized (CP) array antenna is proposed. The antenna element comprises a square ring resonator, a square parasitic patch, and a vertical virtual ground (VVG) structure. To achieve circular polarization, truncated corners are etched on both the resonator and the parasitic patch; meanwhile, the VVG structure is introduced to enhance miniaturization and improve circular polarization performance. The operating mechanism of the proposed antenna element is analyzed in detail. Furthermore, a one-to-four microstrip power divider is designed to feed a 2 × 2 array, which occupies an area of 1.07λ02. For verification, the 2 × 2 array has been fabricated and measured. The measured results indicate that the proposed antenna operates at a center frequency of 17.2 GHz with a bandwidth of 14.4%. Additionally, it exhibits a 3 dB axial ratio bandwidth of 6.52% and a maximum gain of 8.64 dBi. With excellent CP performance and compact size, the proposed CP array is an attractive candidate for high-resolution radar and satellite communications.