A design method of broadband polarizers using metal posts

AbstractA broadband polarizer with metal posts is designed on the basis of the fact that normalized capacitive susceptance of short posts decreases at high frequencies. To obtain the design data, the measurement is made for the optimum post diameter and its length which give negative normalized capacitive susceptance, and the magnitude of the post susceptance for the orthogonal two polarized waves. A method of determining the post size for a broadband polarizer is examined from the equivalent circuit. To obtain good VSWR characteristics, the post susceptance in the matching sections follows the raised cosine distribution. The relation between the number of posts and VSWR is clarified. An experimental polarizer has an ellipticity less than 0.25 dB in the specific broadband 12.6%.