The design of parallel coupled line filter with arbitrary image impedance

In this paper, new design equations are presented to implement a parallel-coupled line filter with arbitrary image impedance. These equations are more accurate than the conventional design method. They have an advantage that the designer can control the coupled line width and gap. Hence they are applicable to the design of parallel-coupled line BPFs using high dielectric material. Also, they can be applied to fin-line waveguide filters and hairpin line filters.