Abstract: Coupling between non-adjacent resonators and wave propagation through the waveguide structure in distributed EM filters are reduced by forming one or more holes in one or more of the resonators (planar or folded) and by passing a conductive structure through each hole normal to the resonator. The conductive structures (vertical vias or horizontal strips) are preferably grounded, either by direct connection or capacitive coupling to one or more ground planes or by creation of a virtual ground. The holes are spaced apart from the edges of the resonator so as to minimize any interference with the current and fields concentrated at the edges of each resonator. These conductive structures narrow the effective cavity width “aeff” for the waveguide as a whole and between non-adjacent resonators without affecting the cavity width “a” between adjacent resonators.

Abstract: Coupling between non-adjacent resonators and wave propagation through the waveguide structure in distributed EM filters are reduced by forming one or more holes in one or more of the resonators (planar or folded) and by passing a conductive structure through each hole normal to the resonator. The conductive structures (vertical vias or horizontal strips) are preferably grounded, either by direct connection or capacitive coupling to one or more ground planes or by creation of a virtual ground. The holes are spaced apart from the edges of the resonator so as to minimize any interference with the current and fields concentrated at the edges of each resonator. These conductive structures narrow the effective cavity width “aeff” for the waveguide as a whole and between non-adjacent resonators without affecting the cavity width “a” between adjacent resonators.

Abstract: A printed circuit board. The novel printed circuit board includes a substrate, a layer of conductive material disposed on the substrate, and a solder mask layer disposed on the conductive layer, the solder mask layer including cutouts shaped as reference text and/or art. The conductive layer is etched to form traces for connecting electronic components to be mounted on the board in a desired pattern to form an electrical circuit and may include pads and lands to which the components are to be soldered. The solder mask layer is made from a material that resists wetting by solder and also includes cutouts in areas where the components are to be soldered to the conductive layer. The reference text and/or art includes readable information for assembling, testing, and/or repairing the circuit board, such as component part numbers, reference designators, pin one identifiers, component outlines, and test point identifiers.