A Dual-Broadband Dual-Polarized Directional Antenna for All-Spectrum Access Base Station Applications

A dual-broadband, dual-polarized directional antenna with an electrical down-tilted beam is designed for all-spectrum access base station applications. Three columns of elements are deployed in the manner that six lower-band elements are placed in the center column while the eleven upper-band elements are arranged in the other two columns. Moreover, each column of elements are fed by two ports, which makes the proposed antenna suitable for multiple-input-multiple-output (MIMO) applications. To verify the design concept, a prototype is fabricated and measured. The measurement results confirm that the proposed antenna achieves a bandwidth of 31.6% (698-960 MHz) for VSWR<; 1.5 in the lower band and a bandwidth of 44.5% (1710-2690 MHz) for VSWR<; 1.5 in the upper band, covering all the frequency bands for 2G/3G/LTE systems and 700 MHz/2.6 GHz frequency bands. The measured gains are 17.4 ± 0.9 dBi, 17.3 ± 0.8 dBi, and 14.4 ± 0.9 dBi for the antenna port1, port2, and port3, respectively, while the third-order passive intermodulation (PIM
₃
) is larger than 115 dBm at all frequencies. With these distinctive advantages, the proposed antenna is suitable for multi-band base stations.