The purpose of this program is the attainment of low-noise amplification over two octaves in a single traveling-wave tube. Noise figure is to be less than 6.5 dB from 0.5 to 2.1 GHz with a minimum of three milliwatts saturated power output. The work described herein has been aimed primarily at raising the power output to the required three milliwatt level and achieving uniform gain over the full band. This has been sought through the use of a servered helix, with the output section operating with higher voltage and lower gamma than the input, or low-noise section. Good results have been obtained with this method, the power output being greater than two milliwatts over practically the entire band. It is concluded that this approach is entirely feasible technically, and that future effort will be expended applying it to reduce gain variation at an increased power level. At present, noise figure of the tube is within the specification over all of the band. (Author).

A low noise traveling wave tube amplifier packaged with integral solid state power supply and permanent magnet focusing was developed to cover the frequency band 18 to 40 GHz. The amplifier noise figure lies between 13 and 14 dB; the minimum small signal gain is 32 dB, and the gain variation is plus or minus 2.7 dB. The minimum saturated power output is + 6 dbm. The tube employs a hollow beam six anode low noise electron gun. A unique ridge waveguide coupler was developed to cover the double waveguide band. A key factor in reducing gain variation was development of an improved 'skrunching' method for the fluted glass helix support structure. The tube completes a series of four low noise traveling wave tube amplifiers covering the 0.5 to 40 GHz frequency band. (Author).

An X- and K sub u-band, low-noise traveling-wave tube amplifier covering the 8 to 18 GHz frequency range was developed. This amplifier exhibits a maximum noise figure of 8.6 dB over 100 percent of the band and a 7.5 dB maximum noise figure over 60 percent of the band. Nominal small signal gain is greater than 30 dB, and saturated power output ranges from +5 to +10 dBm in an 18 pound, 4.5 inch diameter package. The design of this broadband amplifier is a logical extension of several known techniques including the fabrication of uniform dense cathode, low-loss circuits, broadband low-reflection couplers, and uniform, low transverse field permanent magnets, as well as considerable experience and knowledge gained in the earlier development of narrow band amplifiers in X- and K sub u-band. The performance of this X- and K sub u-band amplifier is superior to presently available low-noise amplifiers in K sub u-band alone, and it opens up applications for new wideband receiving systems with reduced complexity and cost. (Author).

The report describes the design and development of the WJ-276-6, a 5 dB terminal noise figure, 8.0 to 12.0 Gc/s, permanent magnet focused traveling-wave tube amplifier with integral power supply. The major problem in the development was reducing the terminal noise figure to less than 5 dB, while keeping the weight of the amplifier to less than 15 pounds. This problem was solved by the use of a hybrid straight field magnet, which provided a peak magnetic field of 1500 gauss in the critical region of the cathode and electron gun; a high gamma a, low RF loss helix assembly; a novel thin-rim cathode and flexible low noise gun assembly; and low RF loss waveguide input coupling. The report describes the important design considerations and the effect of the design parameters on traveling-wave tube performance. A physical description of the tube is presented along with important fabrication and measurement techniques. The progress which lead to the final design is chronicled, and the initial and final design values compared. (Author).