Broadband multimode antenna and its array for wireless communication base stations

A wideband dual-polarized antenna coupling cross resonator is proposed for LTE700/GSM850/GSM900 base stations. An additional resonance is introduced to obtain strong coupling between the dipole and resonator. Moreover, the input impedance of the proposed antenna is steadily close to $50{\Omega}$, which results in better impedance matching. Therefore, a wide bandwidth can be achieved with multiresonance. A prototype is fabricated to verify the proposed design. The measured results show that the antenna has a fractional bandwidth of 35.7% from 690 MHz to 990 MHz for ${\mid}S_{11}{\mid}$ < -15 dB. Stable radiation patterns as well as gain are also obtained over the entire operating band. Moreover, a five-element antenna array with an electrical downtilt of $0^{\circ}$to $14^{\circ}$ is developed for modern base station applications. Measurement shows that a wide impedance bandwidth of 34.7% (690 MHz to 980 MHz), stable HPBW (3-dB beamwidth) of $65{\pm}5^{\circ}$, and high gain of $13.8{\pm}0.6dBi$ are achieved with electrical downtilts of $0^{\circ}$, $7^{\circ}$, and $14^{\circ}$.