Design Of Multi-beam Array Antennas And Shaped Reflector Antennas

With the advantages of high gain and beamforming capacity, array and reflectorantennas have attracted extensive applications in communication, radar, and navigation.To realize the more and more complicated design demands by means of optimizationmethod is always the most important direction for antenna designers.In this thesis, we focus on the optimization design of the helix antenna array withmulti-beam switching and the shaped reflector antenna using the differential evolutionalalgorithm, the main contribution includes two aspects:First of all, an antenna array with multi beam switching capacity for highfrequency transceiver is designed. This antenna is composed by thirty axial mode helixantennas, with upper-bottom two layers’ architecture conformal to the side of the conefrustum. Besides, on each layer fifteen elements are arranged uniformly. Theneighboring five elements on the two layers are selected to compose the subarray, andthe amplitude and phase of the response of each array element are calculated by meansof differential evolution algorithm. Two kinds of beams, i.e., high elevation angle beamand low elevation angle beam, are generated to realize the pitch plane to be between-10°and+50°, high and low elevation angle beams scan switching, and also azimuthscan switching with thirty groups of beams.Then a single offset shaped reflector antenna is designed for lower space areamonitoring. The surface of the reflector is expressed by a complete orthogonal functionset (Jacobian-Fourier function), far field radiation field is calculated by physical opticalmethod. The coefficient of the reflector is optimized by differential evolutionalalgorithm and then beamforming is accomplished. The reflector is processed by mouldmethod, the measured results show that the horizontal elevation angle is2°in themaximum radiation direction, the elevation angle shows a cosecant distribution within2°and20°, the gain in-1°direction is3dB less than the maximum gain, and theradiation pattern meet the requirements.