Crisscross-Shaped ±45° Dual-Polarized Antenna With Enhanced Bandwidth for Base Stations

In this communication, a +/- 45 degrees dual-polarized antenna for 690-960 MHz base station applications is proposed. The proposed antenna has a crisscross-shaped radiator which is fed by four triangular-shaped couplers. The +/- 45 degrees dual polarization is achieved by vector synthesis of the currents on the radiator. To further broaden the impedance bandwidth (IBW), a miniaturized lowpass filter is designed and integrated with the baluns of the proposed antenna. With the lowpass filter, a new resonance is introduced and harmonic suppression is also realized. The experimental results which agree with the simulations show that wide harmonic suppression bandwidth which can cover the interference bands (1.69-2.69 GHz and 3.3-3.8 GHz) is obtained. In the operating frequency band (690-960 MHz), a voltage standing-wave ratio (VSWR) of less than 1.5, a polarization isolation (ISO) of more than 35 dB, a half-power beamwidth (HPBW) of 66.8 degrees +/- 1.5 degrees, and the gains of 8.3 dBi +/- 0.2 dBi are obtained by the proposed antenna.