Applications of nonuniform transmission lines in filters

In this paper, nonuniform transmission lines (NUTLs) are used to design various types of filters. The characteristic impedance of NUTL can be expanded as truncated Fourier series. The optimized values of series coefficients are obtained by some optimization process. The characteristic impedance can then be determined and the width of the structure can be obtained. The performance of the designed filters is assessed by the well-known software packages high-frequency structure simulator (HFSS) and computer simulation technology (CST).