Antenna Radiation Characteristics Optimization by a Hybrid Topological Method

A hybrid topology optimization method that integrates material distribution and level set methods (LSMs) is proposed. The topology of the antenna is optimized first by the material distribution method, and then, the derived structure, which has a zig-zag boundary, is further optimized by the LSM. By adopting this hybrid strategy, the powerful topology-searching ability of the material distribution method and the advantageous feature of producing structures with smooth and low sensitivity boundary of the LSM are fully exploited. To optimize antenna's radiation characteristics, sensitivity analysis of the power density of the far-field is formulated. To demonstrate the capability of this hybrid topology optimization method and verify the sensitivity analysis formulation, three microstrip antennas with different desired polarizations, beam directions, and bandwidths are designed and tested. The measured results show that all the antennas not only achieve low reflection in the prescribed frequency band, but also give good performances in gain and polarization in the desired beam directions.