Abstract: A receiver system and method of operation are used to tune a selected channel from an input spectrum. The receiver includes an up-converter which responds to a selection setting for up-converting the input spectrum, including the selected channel and an unwanted spectrum; a first diplexer for dissipating the energy of the unwanted spectrum in a manner to reduce distortion effects on the up-converter; a down-converter for down-converting the up-converted selected channel having associated upper and lower sidebands and an intermediate frequency component; and a second diplexer for dissipating the energy of the upper and lower sidebands of the down-converted selected channel in a manner to improve intermodulation of the down-converter.

Abstract: The problems of high cost, high loss and incomplete distortion compensation are resolved in a distortion generating circuit which employs a nonlinear phase modulator (70, FIG. 7) and a linear phase shifter (71) as a means of generating selected distortion signal components. The circuit includes an output coupler (30) and an output coupler (31) interconnected by means of a pair of wavepaths (32, 33). The nonlinear phase modulator (70), which includes a nonlinear reactive element (37), is disposed in one of the wavepaths (32). The linear phase shifter (71) is included in the other wavepath (33). By the appropriate adjustment of the linear phase shift in wavepath (33) the entire gamut of distortion characteristics can be compensated. Distortion generating circuits of the type disclosed can be employed as either predistorters or as postdistorters to compensate for the nonlinearities in electromagnetic signal devices, such as amplifiers.

Abstract: A complementary distortion circuit for reducing the level of IM products in the output of a TWT amplifier. One embodiment of the invention includes a 3 db, 90.degree. coupler to divide the input signal into two components of equal amplitude but differing phase with an IM generator positioned in the path of each component. The IM generator may comprise non-linear phase modulators or non-linear amplitude modulators. The two components are then re-combined in a second, 3 db, 90.degree. coupler. The non-linear phase-modulators may comprise varactors and the non-linear amplitude modulators may comprise varistors. The unit is intended to operate in the microwave region.