Numerical analysis of conical horn with dielectric lens in free-space method

A free-space method where a pair of conical horns with dielectric lenses are used has an advantage that one can estimate material constants without electromagnetic absorbers. Since the analysis region for the free-space method in a 3dimensional (3-D) electromagnetic analysis is very large, we investigate the usefulness of 2-D FEM analysis and the plane wave spectrum method in 3and 2-D FEM analysis for a conical horn with a dielectric lens in the setup of the free-space method, and illustrate the difference of the focusing property against operating frequencies.