Helix Millimeter-Wave Tube

The experimental results of a program to extend helix backward-wave oscillator techniques to the 4.5- to 6-millimeter range are described. The design of a tube capable of cw output over this range is presented together with operating characteristics. The tube employs a tungsten helix wound with 0.002-inch by 0.005-inch tape with a 0.025-inch inner diameter. The helix voltage is tuned from 2,400 to 850 volts to cover the range, and the cathode current is 4.0 ma. The tube with its all-glass envelope is believed to be a relatively inexpensive millimeter-wave signal source. Power output is estimated to be greater than 1 milliwatt.