Research And Design Of Multi-beam Base Station Antennas

The number of terminals accessing mobile communication networks has grown rapidly since the third generation of mobile communications(3G)and the demand for mobile data services(traffic services)has increased,which has forced mobile operator to pay more attention to the issue of wireless network capacity.In some large cities or communities where the number of base stations is already high and site resources are already very tight,it is becoming difficult to expand capacity using traditional cell splitting.Rather than using traditional wide-angle sector coverage,multi-beam antennas achieve system capacity expansion by using multiple high-gain narrow beams for the same angular range,with different carriers configured for each area covered by an isolated narrow beam.This type of expansion has become increasingly popular among operators as it allows for no re-selection of station sites and is simpler to configure.The focus of this paper is the study and design of a low-cost implementation of a multi-beam base station antenna,and is summarized as below.1.Proposed a compact crossover circuit based on microstrip structure implemented based on the core components of the Butler matrix,enabling a wide band(0.5 to 6 GHz)circuit crossing function.Test result show that the RL of the ports is above 18.4 d B,the isolation of the ports is below-30 d B,the phase difference of the pass-through ports is less than 3°.2.Designed a 3 × 5 Butler matrix with amplitude weighting for its output to address the traditional Butler matrix’s inability to achieve a 0° azimuthal beam,the simulated and measured circuit characteristics meet the requirements of a low side lobe triple-beam antenna feed.3.Improved the feed network of a four-beam antenna from the 4 × 8 to the 4 × 6 matrix network to achieve a better low side lobe level,while reducing the size of the array and improving the crossover level between adjacent beams.The simulated and measured circuit characteristics meet the needs of a three-beam antenna feed with low side lobe.4.Designed a low-profile radiating element operating in the 3.2 to 3.8 GHz band and used it to design an array of three-beam and four-beam antennas.The 3×5 and 4×6 feed matrices were used to feed the antenna and the measured results were in good accordance with the proposed design.