Filter unit and filter

Disclosed are a filter unit and a filter. The filter unit comprises two cavities in a stack configuration. Each of the cavities comprises a dielectric substrate, and a metal coating layer is respectively disposed on two surfaces of the dielectric substrate. Connected coupling slots and a row of metal slots parallel to the coupling slots are etched on one of the metal coating layers. The coupling slots each have an open end and a closed end. The open end corresponds to a magnetic wall structure and the closed end corresponds to an electric wall structure. The two cavities are coupled by means of the coupling slots. In the technical solution of the present invention, two layers of cavities are stacked to form a filter unit, the two cavities are coupled by means of coupling slots to form the filter unit, and feed ports are required to be disposed only on sloping edges of the cavities. By adoption of the structure, the physical size of a conventional filter is effectively reduced, and surface area of the filter unit is decreased.