Design of a 3G base station antenna

Abstract

The conventional microstirp patch antenna has major advantages of low profile and low fabrication cost, but its impedance bandwidth is not wide enough for modern wireless communication systems. Some attractive techniques have been proposed to increase the impedance bandwidth, such as L-probe antenna, whose horizontal part can efficiently cancel the inductance of the vertical part of the probe and results in a large bandwidth. But the major problem is it causes a large cross-polarization radiation. High cross-polarization not only leads to a distortion in the co-polarization pattern, but also reduces the gain of the antenna. Recently a new technique named meandering probe feed has been proposed to suppress the cross polarization. In this project, analysis and design of a meandering probe-feed 3G (operating frequency ranges from 1.9GHz to 2.17GHz) base station antenna are presented. Enlightened by the above-mentioned technique, a new structure with 4 surrounding patches and meandering probe is proposed in this project for both enlarging the bandwidth and reducing the cross-polarization. This increases the antenna complexity in structure, so the results of a structure with 1, 2 and 4 meandering probes are studied and analyzed. Moreover, experimental results of the antenna performance, including impedance matching and radiation patterns are also presented.