A Low Profile Broadband Dual-Polarized Base Station Antenna Using Folded Dipole Radiation Element

In order to satisfy the communication requirements, a low profile + 45° / -45° dual-polarized base station antenna with a spacing of only 23 mm between the reflector and radiating surface is proposed. Different from the more common base station antenna units, the four folded dipoles are arranged in the same plane to form an octagon. When a single polarization is excited, the four folded dipoles are excited as a whole. Furthermore, two meandering L-shaped feeding lines are used to achieve a larger impedance bandwidth. Ultimately, this antenna has a relatively wide impedance bandwidth of 44.5% from 1710 to 2690 MHZ. The use of a reflector contributes to the formation of a stable radiation pattern, and aids in the realization of high cross polarization discrimination (XPD) available in the whole working frequency band. The antenna geometry description and operation principle are elaborated and several important parameters are also studied. The fabricated antenna array consists of 2 × 12 elements and the measurement results obtained demonstrate that the array meets the requirements in all bands of the DCS1800, PCS, 3G, and traditional WiMAX for modern communication on the eve of the 5G.