Wideband Dual-Polarized Four-Folded-Dipole Antenna Array With Stable Radiation Pattern for Base-Station Applications

This article presents a wideband ±45° dual-polarized six-element antenna array with stable radiation pattern for base-station applications. Each element consists of four folded dipoles, a parasitic patch, and a convex-shaped reflector. To generate ±45° dual-polarized radiation pattern, the four close-in folded dipoles are arranged uniformly in a square shape and excited simultaneously by two integrated baluns. The parasitic patch is placed above the folded dipoles to enhance the impedance bandwidth for reaching 64.7% (VSWR <; 1.5 within 1.4-2.77 GHz), while the reflector is designed in a convex shape to stabilize the horizontal radiation pattern. To further optimize the horizontally 3 dB beamwidth in the whole frequency band, six antenna elements are divided into three element pairs. Each element pair consists of two antenna elements which are misaligned in the horizontal plane. Using this method, the 3 dB beamwidth is stabilized within the range of 65.7° ± 3.2°. The impedance bandwidth is measured to be 64.8% (1.39-2.76 GHz) for VSWR <; 1.5. Port-to-port isolation of 27 dB and side-lobe level better than 16 dB are obtained. These results make the proposed design attractive in wideband base-station applications.