The invention discloses a double
passband differential filter having a laminated substrate integration
waveguide structure. The filter includes a medium substrate, an upper surface
metal layer, a middle
metal layer and a lower surface
metal layer. A metallization through hole array penetrating through the medium substrate is arranged in the medium substrate. Six substrate integration
waveguide cavities are defined by the metallization through hole array, the upper surfaced metal layer, the middle metal layer and the lower surface metal layer. The
center frequency of the two differential passbands is obtained through adjusting upper layer cavity dimension parameters. At the same time, the middle metal layer is etched with an H-type
coupling slot line. Through adjusting the size and the position of the slot line, a demanded
coupling index is obtained, so that better
frequency response is achieved. According to the invention, a second difference module
passband is obtained by utilizing a substrate integration
waveguide high order mode, the size of the filter is reduced effectively. Besides, through adjusting the position or the size of the metal
etching slot line in the lower surface, common mode rejection and inter-band isolation are improved.