Abstract: A waveguide directional filter for combining multiple high power UHF television broadcasting transmitters on to a common antenna. The directional filter arrangement includes an input waveguide, an output waveguide and an interconnected cascade assembly of two or more cavity resonators. The input and output waveguides are each aperture-coupled to an end cavity resonator of the cascade assembly. The edges of each aperture incorporate inwardly extending curved protrusions of a characteristic shape. Alternatively or additionally, at least one pair of non-adjacent cavity resonators are coupled by at least one additional coupling element incorporating an external transmission line.

Abstract: This invention discloses an improved thermal compensation arrangement for a microwave filter of the type comprising at least one cavity defined by a metal side wall having a low coefficient of thermal expansion, such as invar, and lightweight metal end walls, such as aluminum, having good thermal and electrical conductivity, but a high coefficient of thermal expansion. The present invention comprises a characteristic arrangement of annular grooves and slots in the end walls that mechanically isolate the end walls from the side wall fixed thereto, to avoid distortion of the cavity with changes in temperature.

Abstract: An adjustable coupling arrangement for aperture coupled cavity filters. According to the invention, in an electric wall (24) separating two cavities to be coupled in a bandpass filter, provide a cruciform iris (26) comprising a central aperture (27) having four slits (28,29,30, 31) extending outwardly therefrom. In each slit there is arranged a captive movable rectangular metal slug (36,37,38,39) whose position along the slit's length can be manipulated by a tool that engages the slug when the tool is introduced into a radial passageway (32,33,34 35) that connects the slit with an access hole in the filter's housing. When desired coupling parameters are achieved by manipulating each of the slugs to effectively change the electrical length of the slits, each slug is locked in position by a respective associated locking means actuated by the tool. Because a significant part of the tool is within a passageway during manipulation, the filter's characteristics are not disturbed by its presence.

Abstract: This invention discloses an improved thermal compensation arrangement for a microwave filter of the type comprising at least one cavity defined by a metal side wall having a low coefficient of thermal expansion, such as invar, and lightweight metal end walls, such as aluminium, having good thermal and electrical conductivity, but a high coefficient of thermal expansion. The present invention comprises a characteristic arrangement of annular grooves and slots in the end walls that mechanically isolate the end walls from the side wall fixed thereto, to avoid distortion of the cavity with changes in temperature.

Abstract: An adjustable coupling arrangement for aperture coupled cavity filters. According to the invention, in an electric wall (24) separating two cavities to be coupled in a bandpass filter, provide a cruciform iris (26) comprising a central aperture (27) having four slits (28,29,30, 31) extending outwardly therefrom. In each slit there is arranged a captive movable rectangular metal slug (36,37,38,39) whose position along the slit's length can be manipulated by a tool that engages the slug when the tool is introduced into a radial passageway (32,33,34 35) that connects the slit with an access hole in the filter's housing. When desired coupling parameters are achieved by manipulating each of the slugs to effectively change the electrical length of the slits, each slug is locked in position by a respective associated locking means actuated by the tool. Because a significant part of the tool is within a passageway during manipulation, the filter's characteristics are not disturbed by its presence.