Design of a Third-Order Filter with 10 GHz Center Frequency

Filters are extensively applied in the field of communication artificial intelligence. The input–output coupling structure and the stage coupling structure of substrate integrated waveguide (SIW) resonator are introduced in this paper. The transmission characteristics of SIW are studied by means of the electromagnetic field distribution and surface current of rectangular waveguide. Combined with the basic theory and the general design method of coupled resonant filter, as well as the metal via hole design requirements of SIW, a third-order filter with center frequency of 10 GHz, relative bandwidth of about 2.4%, and return loss in the pass band better than −12.5db is designed by using the electromagnetic simulation software HFSS.