A spiral antenna with a circular reflector

A numerical solution for a spiral antenna with a finite reflector is presented. The analysis is based on the method of moments (MoM) and Galerkin's matching. The antenna geometric parameters are optimized to obtain the best circular polarization (CP) axial ratios (AR) in the main beam of the pattern. A block matrix inversion technique is used for the computation to be more efficient. Simulated results are well consistent with the measured ones, while the antenna height is less than a quarter of wavelength.