Dual-polarised antenna using unbalanced power dividers for small-cell base stations
A compact, dual-polarised multiple-input and multiple-output antenna for small-cell base stations is proposed. This antenna is operating at long-term evolution (LTE) band-5 and consists of two stacking substrates and cavity-backed structures. To produce dual polarisation, two edges of the feeding patch on the lower substrate are individually fed by unbalanced power dividers with a phase difference of 90°. These unbalanced power dividers improve the isolation characteristic of this antenna. Measured results show that the proposed antenna has a port isolation higher than 30 dB over the operating range of 820–900 MHz. Furthermore, a high front-to-back ratio of 13.5 dB is obtained in spite of the compact size because there are no slots on the ground plane.
