Compact Dual-Band Dual-Polarized Base-Station Antenna Array With a Small Frequency Ratio Using Filtering Elements

This paper presents a compact dual-band ±45° dual-polarized base-station array based on embedded filtering elements. The proposed antenna array consists of 9 dual-band antenna units, which operate at the lower band (LB) of 790-862 MHz and the higher band (HB) of 880-960 MHz with a small frequency spacing. In each unit, one antenna element is embedded into the other one, featuring a very compact size. To alleviate the serious cross-band mutual coupling between the two elements, the LB patch antenna generates a boresight radiation null at its higher band edge, and the HB element is designed with a band-stop response at its lower band edge. In this way, high cross-band isolation between the two embedded elements can be obtained. For demonstration, a compact dual-band ±45° dual-polarized filtering antenna array with 9 units is designed and fabricated to fit the specification of LB and HB bands (|S
₁₁
| <;-15 dB). The overall width of the array is only 280 mm, which is much narrower than that of typical industrial products using two side-by-side sub-arrays (~576 mm). The measured performance of the antenna array can meet the requirement of base stations.