A ceramic waveguide filter, a radio unit, an antenna unit and a base station are disclosed. According to an embodiment, a ceramic waveguide filter comprises a body (1) that is made of a ceramic material and that has a plurality of resonators each including a blind hole (101). The blind holes (101) of two of the resonators open at a first surface of the body (1) and extend toward an opposite second surface of the body (1). Capacitive coupling between the two resonators is achieved by a coupling structure (201) on/in a substrate (2), to which the body (1) is attached at the side of the second surface.