A Compact 1:3 Power Divider Incorporating 180° Shifted Path for Polarization Purity Enhanced Base Station Subarray

This paper presents a compact 1:3 power divider and a base station subarray antenna with enhanced polarization purity exhibiting high cross-polarization discrimination (XPD) and high input port isolation. The compact 1:3 power divider incorporating a 180° shifted path is proposed to achieve both polarization purity and the wideband characteristics of the subarray antenna, which is difficult to implement using the conventional dual-feed method in limited areas. Using the proposed power divider, a dual-polarized quadruple Π-probe feed stacked patch antenna array is designed, which achieves a wide bandwidth of over 30% (< -13 dB) from 1.68 GHz to 2.25 GHz. The XPD is increased by approximately 8 dB and 5 dB at 1.71 GHz and 2.11 GHz, respectively, to attain an increase in the isolation bandwidth (< -20 dB) from 14% to 43%. Furthermore, the measurement results of a 4 × 3 antenna array confirm the effectiveness of the proposed design in terms of XPD and isolation while maintaining the bandwidth and beam performance. This study demonstrates a relatively wide bandwidth between patch antennas, despite the use of multiple subarrays. The comparative results also show a relatively better frontto-back ratio and isolation of the proposed design.