Decoupling of Planar Circularly Polarized Patch Array by ADS and Parasitic Structure

A decoupling method for 2 × 2 circularly polarized (CP) patch antenna arrays is proposed in this letter. Four CP antenna elements surrounded by substrate-integrated waveguide cavities consist of two layers of chamfered patch antennas and are rotated through 90° in sequence to form an array. The partially reflective surface above the array introduces a new coupling path, which cancels out a part of the coupled waves. The metal structure serving as a parasitic loaded monopole in the center of the array further improves the isolation. The measured results show that the 3 dB axial ratio (AR) bandwidth can reach 5.8%, and all isolations are higher than 25 dB from 3.35 GHz to 3.55 GHz. The active voltage standing wave ratio of the proposed array is also presented to demonstrate the effectiveness of the decoupling method.