Abstract: A multiplexer has a plurality of manifolds interconnected by bandpass filters of differing spectral passbands. The filters serve to segregate signal channels from each other during a process of separating microwave signals in one of the manifolds and in a process of combining the microwave signals associated with another of the manifolds. A compact rigid structure of reduced mass is attained by employing one or more of the bandpass filters as connecting filters for coupling a signal channel directly between a first of the manifolds and a second of the manifolds, wherein the construction of the manifold and the connecting filters is in the form of a rigid assembly. A base may be provided for supporting each of the manifolds and each of the bandpass filters in a unitary structure.

Abstract: A method of tuning individual filters in an assembly of filters connected to a manifold, such as a microwave multiplexer, prior to assembly of the multiplexer, is accomplished by energizing a subject filter to be tuned with an electromagnetic signal provided by a network analyzer. The filter is tuned by adjustment of a tuning component, such as a tuning screw within the filter, while the network analyzer presents the transfer function of the filter during the tuning process. To compensate for tuning effects of the other filters and of the manifold, which are manifested upon a connection of the filters to the manifold, the transfer function of the assembly is loaded into a computer of the network analyzer. Thereby, during a tuning of the filter, the presentation of the filter transfer function by the network analyzer includes the tuning effects of the rest of the assembly.

Abstract: Apparatus and method for filtering an electromagnetic signal employs the feeding of the signal via a rectangular waveguide to a plural mode cavity filter with coupling available at plural modes. The cavity has a mode-coupling structure such as a mode-coupling screw. The waveguide operates at a first mode of lower cutoff frequency and a second mode of higher cutoff frequency. The feeding is at a frequency for propagation in the first mode. The cavity radiates back into the waveguide, or into another waveguide, below the higher cutoff frequency to provide an evanescent reactive loading which reduces the required penetration of tuning screws for reduced dissipation of power in the tuning screws.

Abstract: In a filter assembly having a bandpass filter and a group-delay equalizer coupled thereto by a circulator, there is disposed in the filter and/or the equalizer an electromagnetic wave propagation structure having a cavity with a plurality of tuning elements extending therein. The wave-propagation structure supports a first wave propagating in a first mode and a second wave propagating in a second mode. A first of the tuning elements is positioned to interact with the first wave, a second of the tuning elements is positioned to interact with the second wave, and a third of the tuning elements is positioned for coupling electromagnetic energy between the first wave and the second wave. A fourth of the tuning elements has an orientation perpendicular to an orientation of the third tuning element.