A line of ultra-low-noise amplifiers with integrated solid-state power supply

The low-noise characteristics of the traveling-wave tube, which have previously been obtainable only with solenoid focusing, have now been achieved in shielded permanent-magnets. This paper describes a family of low-noise traveling-wave tubes from L through Ku-band. The four tube types covering the band 1 through 12 Gc are focused in straight-field Alnico permanent magnets. External magnetic flux is reduced to a negligible value by shielding. Identical units can operate side by side without mutual interference. All have 25 db minimum gain. Noise figure is typically 4 db in L-band, 4.5 db in S-band, 5.5 db in C-band, and 7 db in X-band. Power output is between -5 and +5 dbm, with the higher values at the higher frequencies. A solid-state power supply with regulated voltages for all tube elements is described. Novel use of the annular space between the permanent magnet and the shield has resulted in a complete amplifier no larger than the shielded package without the power supply. Designed for a wide range of environmental conditions, peformance is guaranteed from -54° C to +85° C, for 10 g vibrational forces, and adequate protection from high humidity, altitude, and shock. The Ku-band tube is solenoid focused. Power required for the 1300-gauss field is 500 watts. Noise figure is less than 10 db from 12 to 18 Gc, and values less than seven db have been obtained with developmental models.