A Dual-Band Dual-Polarized Antenna Array Arrangement and Its Application for Base Station Antennas

This letter presents a dual-band, dual-polarized antenna array arrangement for low grating lobe base-station antenna applications. The presented array arrangement uses two different lower band elements to achieve a 2.5-time element spacing array scheme, in which lower band elements spacing is 2.5 times of upper band elements spacing. With this arrangement, both the lower and upper band element spacing can be reduced, leading to a better grating lobe performance. To verify the idea, an antenna array operating at two bands, namely, 690-960 and 1690-2690 MHz, is presented. For 690-960 MHz array, two different radiation elements are designed, each of them has two pairs of bent dipoles for dual-polarization operation. The smaller lower band element is embedded with one upper band element. Meanwhile, the larger one is embedded with two upper band elements. An array consisting of five lower band elements and 12 upper band elements is fabricated and tested. Measured results show that the array has a good performance with return loss larger than 15 dB, ports isolation better than 28 dB. Besides, the grating lobe value is better than -12 dB at tilt angle 12° for both upper and lower band, which is a significant improvement over its former counterparts.