Abstract: A circuit for compensating for GaAs FET amplifier gain variations over a frequency band as a function of temperature. The circuit includes a passive equalizer circuit having a fixed gain over the frequency band and an active equalizer circuit having a gain which varies over the frequency band as a function of temperature. The passive and active equalizers are coupled in series. The active equalizer circuit comprises varactor diodes in a low pass filter arrangement with the bias voltage of the varactor being provided by an external driver controlled by a temperature sensitive thermistor. As the value of the varactor's junction capacitance is increased (as a function of the temperature controlled bias voltage), the cutoff frequency of the low pass filter decreases.

Abstract: A multibeam antenna having a radio frequency lens fed by a plurality of feedports is disclosed. The radio frequency lens includes a printed circuit parallel plate region and a polarizer section. The polarizer section includes a plurality of polarizer sheets separated by a plurality of layers of dielectric material, the dielectric constant of the printed circuit parallel plate region and the dielectric constant of the layers of dielectric material being selected to form substantially collimated beams, each one of such beams being associated with a corresponding one of the feedports. With this arrangement, the polarizer section is an integral part of the radio frequency lens, thereby reducing the size of the antenna.