Study and design of K-band active phased array multibeam antenna and its application for source positioning

Abstract

Since fixed beams on satellite could face some business risks when service environment change, onboard satellite systems have been forced to be equipped with intelligent antennas. On the other hand, a new generation of wireless network on the ground has been evolving from independent fixed networks into a ubiquitous network to provide global seamless wireless services to subscribers which connects the satellite and ground networks. Regarding these, recently, phased array antennas (PAA) with rapidly reconfigurable multiple spot beams have been studied and developed by a few leading companies and institutes. Furthermore, the multibeam has advantages in localization when multiple area source positioning is required on the earth simultaneously. In this dissertation, we first investigate the PAA theory, and derive optimum parameters for linear and planar arrays. We will conduct a performance simulation of different types of array apertures and valuable insight into the effects on the sidelobe level and beamwidth distortion. Since selection of a radiator element is a little bit more complicate in physical size, an extensive analysis will be presented. We also look into the multibeam antenna techniques, and present a beamforming network(BFN) with a 20 $\chi$ 24 array structure based on 4$\times$1 beamforming block (BFB), which is a fundamental element for the array. During the design of the BFN, analysis on digital phase shifter is extensively discussed and analyzed about quantization error and its effect on the SLL and beam accuracies. The designed PAA utilizes a proposed dual mode horn, which has internal choke ring. We implemented a 4$\times$4 phased array subsystem for study purposed and compared it with the theory or the design numbers. The results showed quite a good match with the design. An application of the multibeam antenna to a localization of an object on the earth using GEO satellites will be presented with TDOA accuracy analysis. In this analysis, ...