Dual-Band Dual-Polarized Antenna Array With Flat-Top and Sharp Cutoff Radiation Patterns for 2G/3G/LTE Cellular Bands

Abstract

This paper proposes a dual-band dual-polarized planar antenna array with flat-top and sharp cutoff radiation patterns for 2G/3G/LTE base stations. The array consists of $8 \times 8$ antenna elements arranged with nonuniform spacings and is assigned with optimized nonuniform excitations to achieve flat-top and sharp cutoff radiation patterns with low sidelobes. The radiating element consists of two square-shaped PCB boards. Extra adjustable coupling elements are introduced in the H-shaped patches to improve the impedance matching performance in an array environment as well as to reduce the size of the antenna element. In the 1.71–2.69 GHz band, the dual-polarized radiating element exhibits stable radiation patterns, excellent impedance matching (VSWR 40 dB). Frequency band selective variables are defined to group the antenna elements. They are optimized along with the element spacings and complex excitations in the optimizer to ensure stable flat-top radiation patterns. Rectangular-shaped baffles are introduced to reduce mutual couplings. A prototype of the $8 \times 8$ antenna array has been fabricated and measured. The results indicate that the proposed dual-band dual-polarized planar array achieves a half-power beamwidth of 50° ± 5° in both the H-plane and E-plane. The proposed antenna and its array exhibit attractive potentials for 2G/3G/LTE base station applications.