Abstract: A point-to-point radio frequency unit/antenna has a flat antenna, preferably a continuous transverse stub antenna, integrated into the housing of the microwave unit. The radio frequency unit/antenna includes a housing having an exterior wall, a microwave radio frequency transceiver electronics package within the housing and having an antenna connection, and a flat antenna affixed to one face of the exterior wall of the housing. A microwave radio frequency feed communicates between the flat antenna and the antenna connection of the microwave transceiver electronics package. There is preferably a bracket structure on another face of the housing to affix the housing to a support.

Abstract: Multiple gain stages are provided in a single traveling wave tube amplifier (TWTA). Each gain stage comprises an interaction circuit, an associated RF input, and an associated RF output. The gain stages are separated by a drift length that is selected to achieve a desired interaction between gain stages. In one embodiment that uses only one TWT, couplers, and adjustment blocks external to the TWT, feed-forward and feedback connections remove intermodulation distortion introduced by the TWTA.

Abstract: A refrigeration control apparatus especially adapted for use in conjunction with cryogenic coolers includes a brushless variable speed drive motor for powering a mechanical cooler-compressor and electronic control circuitry coupled to the motor allowing motor speed and hence cooling rate to be responsive to changes in the temperature of the volume sought to be cooled. A signal corresponding to sensed temperature is compared to a reference signal derived from motor speed. The difference therebetween used to vary the duty cycle of a high frequency pulse train. The pulse train is used to modulate the drive current applied to the motor through pulse position switching circuitry to vary the speed of the drive motor. High and low motor speed limits are provided along with sensor failure protection circuitry to insure continuous motor operation between chosen limits.