Reflector Antenna Beam-Shaping Investigation Based On Function Expansion And Particle Swarm Optimization

In this paper, a method of shaped reflector antenna is investigated by direct function expansion of reflector antenna surface and optimization of the expansion coefficients using particle swarm optimization (PSO). It can satisfy the beam shaping needs.First, direct function expansion of reflector surface is analyzed. It uses a complete set of orthogonal basis functions which consist of modified Jacobi polynomials and Fourier functions to express the surface. And examples of parabolic reflector are given. Far-field radiation pattern is calculated by physical optics (PO) to verify the method. Then, PSO is studied to improve the performance. Local searching, chaos and neighbor infection are introduced into PSO. They compose modified particle swarm optimization (MPSO). Test functions are used to verify the algorithm. The test results show that it has advances in convergence velocity and stability.Finally, the MPSO is used to optimize the expansion coefficients of a single offset reflector antenna. The optimized reflector has expected shaping-beams. And the optimized reflector is compared with the original reflector. The surface distortion is continuously. So the direct expansion has advantage.