A Miniaturized Base Station Antenna With Novel Phase Shifter for 3G/LTE Applications

This paper presents a new type of miniaturized base station antenna array, which consists of a metal reflector, six upper-band dipoles, and a couple of ladder sidewalls, operating over 1.71-2.69 GHz (DCS/PCS/UMTS/LTE). Meanwhile, this paper also proposes a novel miniaturized phase shifter with one input and five outputs to enable the antenna array to achieve electrical downtilt (0 degrees-10 degrees) in the operating frequency band. Three different sidewalls are applied in the proposed antenna array to compare their performance. Simulated results demonstrate that the antenna array with ladder sidewalls can achieve an excellent performance, and this proposed phase shifter also has good electrical properties to help the proposed antenna array realize downtilt. The proposed antenna array and phase shifter are fabricated and measured, and the measured results show that the antenna array has good radiation characteristics, including low-voltage standing wave ratio (< 1.4), high port-to-port isolation (> 31 dB), low third-order passive intermodulation (3 < -120 dBm), stable radiation patterns with horizontal half-power beamwidth 65 degrees +/- 5 degrees, high front-to-back ratio (> 30 dB), and high cross-polarization discrimination at +/- 60 degrees azimuth (>11.5 dB) in all frequency bands and electrical downtilt angles. The proposed antenna array exhibits an acceptable gain of 15 +/- 1.1 dBi across the operational frequency band.