Closely-Spaced Half-Ring Patch Antenna Pair With Enhanced Isolation, Reduced Cross Polarization, and Consistent Beam

This letter proposes a copolarized and closely-spaced half-ring patch antenna pair (HRPAP) with loading of stubs and shorting pins for isolation enhancement and cross-polarization reduction. By inserting two stubs and adjusting gaps between the HRPAP, consistent resonant frequency, and equal quality factor of the odd and even modes can be simultaneously obtained, which contributes to high isolation of the HRPAP over a wide frequency range. Furthermore, four shorting pins are elaborately loaded so as to weaken the y -oriented current component of the HRPAP, by which the cross-polarization level in the H -plane is significantly reduced. Finally, the proposed HRPAP is fabricated and measured. Both the simulated and experimental results show that the antenna has achieved an isolation level over 30 dB, cross-polarization reduction of about 8.8 dB, and consistent radiation patterns.