Raytheon Company

Jeremy Bart Baldwin

Kevin W Patrick

Michael R Beylor

Joel Blumke

Sergio E Cardona, Jr

Michael D Gordon

Bradley O Hansen

William L Cagle

David J Karasiewicz

A filter assembly in a multi-layer printed wiring board. One or more conductors is formed on an internal layer of a printed wiring board. Surrounding dielectric layers and ground layers form, together with the conductors of the internal layer, microstrip or stripline transmission lines and distributed element filters. The filter assembly may include a plurality of internal conductive layers, each sandwiched between dielectric layers and ground layers, and each internal layer may include a plurality of distributed element filters. Connections from each filter to the surface of the filter assembly are formed by vias, and connections from the surface of the filter assembly to a host board are formed by solder joints.

Stacked filters

A distributed electromagnetic (EM) wave filter includes: a cavity; upper and lower ground planes on top and bottom surfaces of the cavity, wherein the upper and lower ground planes are in electrical contact; a plurality of electromagnetically coupled resonators in said cavity between the upper and lower ground planes that define respective transmission lines, wherein the plurality of resonators are not connected to each other by a conductive connection; an input port coupled to a first one of the plurality of resonators to receive an EM wave; an output port coupled to a last one of the plurality of resonators to output a filtered EM wave; and a plurality of conductive structures between adjacent resonators, respectively and connected to one or more of the upper and lower ground planes.

Ground structures between resonators for distributed electromagnetic wave filters

A dummy structure for a printed wiring board (PWB) includes a unit shape defined on the PWB, the unit shape configured to, based on a visual inspection thereof, provide an indication of one of: etching of a PWB circuit element within a desired tolerance range, over etching of the PWB circuit element, or under etching of the PWB circuit element.

Dummy structure for visual aid in printed wiring board etch inspection

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 'a' for the waveguide as a whole and between non-adjacent resonators without affecting the cavity width 'a' between adjacent resonators. Consequently the conductive structures have no effect on the desired coupling between adjacent resonators and the desired filter response of parallel-coupled filters while increasing the attenuation of the wave propagating in the waveguide and the attenuation of the wave coupled between non-adjacent resonators.

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Sahuarita, AZ, United States of America

Jeremy Bart Baldwin