Compact Dual-Band Dual-Polarized Interleaved Two-Beam Array With Stable Radiation Pattern Based on Filtering Elements

This paper presents a compact dual-band 4 × 8 antenna array with dual polarizations and two beams for basestation applications. It consists of two 4×4 subarrays operating at 3G (1710-2170 MHz) and long term evolution (2490-2690 MHz) bands. For size miniaturization, the elements of the two 4 × 4 subarrays are interleaved with each other. The mutual coupling between the elements operating at different bands is suppressed by using filtering antennas with out-of-band radiation suppression. And the spacing between them can be decreased, resulting in array miniaturization. To obtain stable two-beam radiation patterns within the two operating bands, the beam-forming networks with little magnitude and phase imbalances are specially designed for each band. For demonstration, the proposed 4 × 8 array is implemented. In the measurement, the array exhibits stable 10-dB beamwidth around 120° in the azimuth plane within the two entire bands. As a result, the two-beam radiation patterns satisfy the coverage requirement of 120° in the azimuth plane for base-station applications. Additionally, 16.4 dBi/15.5 dBi peak gains and around -10 dB cross levels at the junction of two beams are achieved within the two operating bands. Compared with typical industrial products, the proposed array features both compact size and stable radiation patterns. Moreover, the proposed method can easily be extended to multibeam basestation array designs.