A microwave or radio frequency (RF) device includes a substrate and a cover. The substrate has a first surface and an opposing second surface, the first surface including a first RF component and a second RF component electrically coupled to the first RF component in series. The cover is disposed over the first surface of the substrate, where the cover includes a first portion with a first width covering the first RF component, where the first portion and the first surface define a first waveguide cavity having the first width, and a second portion with a second width, less than the first width, covering the second RF component, where the second portion and the first surface define a second waveguide cavity having the second width.