A Dual-polarized Planar Antenna Using Four Folded Dipoles and Its Array for Base Stations

A ±45° dual-polarized base station antenna with a planar structure is proposed for 2G/3G bands. The +45° antenna and the -45° antenna share the same radiator, which is composed of four folded dipoles and four coplanar striplines. The coplanar striplines work as λ/4 impedance transformers. Two Y-shaped feeding lines is designed to obtain a good impedance matching and a planar reflector is employed to achieve a stable radiation pattern. The antenna element has a wide impedance bandwidth of 27.8% with SWR30 dB), a stable radiation pattern with 3-dB beamwidth 65° ± 5° in the horizontal plane, a high XPD and a high front-to-back ratio were achieved.