Abstract: A phase slope equalizer is a recent device used to replace phase shifters in feed networks for satellite communications antennas. The phase slope equalizer has been further refined so that, once manufactured, it does not require tuning and is well suited to integration in larger systems. Three main embodiments are disclosed, one based on a waveguide configuration and the other two on a square coaxial configuration. In the case of the waveguide configuration half wavelength short-circuited stubs spaced by a quarter wavelength are used and in the case of one of the square coaxial configurations half wavelength open-circuited stubs spaced by a quarter wavelength are used. The third embodiment uses quarter wavelength short-circuited stubs spaced by a quarter wavelength.

Abstract: A duplexer for use in a feed network for a satellite communications antenna is made in waveguide form and comprises two plate halves each with a pattern of channels on one surface, the pattern on one half being the mirror image of the pattern on the other. When the two halves are assembled with the patterned faces juxtaposed, a receive filter and a transmit filter with receive, transmit and common ports are obtained. Each filter has a main waveguide and several short-circuited half wavelength stubs in serial connection to the main waveguide. The joint between the two halves bisects the waveguide broadwall and is, therefore, of no electrical significance. The simplicity of the design lends itself to fabrication as part of a bigger integral assembly consisting of duplexers and other feed components. After manufacture, no further tuning is necessary.

Abstract: A microwave antenna feed network dispenses with the conventional phase shifters. Instead, the required phase relationships between the different individual antenna components is achieved by means of a new device, known as a phase slope equalizer, placed in each feed line. This device is formed of a section of waveguide containing one or more resonant circuit elements. Each element comprises, for example, a pair of spaced inductive posts and capacitive tuning screw, or an inductive iris and a capacitive tuning screw, or a resonant slot. The phase slope equalizer exhibits a substantially constant slope phase shift/frequency response curve extending from a positive phase shift through zero phase shift at midband to a negative phase shift. The device is simpler and smaller than the conventional phase shifter and fewer are required thereby reducing costs.

Abstract: A dual mode filter, known in the art as a fourth order filter, has cylindrical coaxial input and output cavities that are connected through a coupling obstacle. The output of the dual mode filter is provided via a connector that carries a probe which extends within the end cavity. The input cavity supports a propagation therethrough of signals within a pass band of frequencies and within a parasitic band of frequencies. The diameter of the end cavity is smaller than the diameter of the input cavity, thereby causing the end cavity to suppress signals within the parasitic band.

Abstract: A transponder includes twelve directional filters that operate in both band stop and band pass modes. The pass and stop bands of each filter has a center frequency that is substantially the same as the center frequency of one of twelve signal channels of the transponder, whereby each channel corresponds to a filter. The twelve filters are connected to a rectangular waveguide at selected relative displacements from a downstream end thereof. Signals within one of two groups of six alternate adjacent channels are propagated through their corresponding filters and through the downstream end without either an undesired signal loss or an undesired group delay. Signals within five channels of the other group are propagated through their corresponding filters and through the downstream end with a symmetrical loss of the highest and lowest frequency portions thereof.