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

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 × 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 <; 1.5), and high isolations (>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 × 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.