Development of an X-Band Printed Circuit Traveling Wave Tube

摘要

The printed circuit traveling wave tubes that were developed on this program were designed for use in an airborne electronically-scanned microwave aperture. Conventional traveling wave tubes are available which provide the required power but are of greater size, weight and cost than is allowable. Solid state devices on ceramic microstrip substrates can be miniaturized to meet the size requirements, but do not provide enough power and are too high in cost. The printed circuit traveling wave tube achieves small size and weight and low cost by using a radically new approach. All the tube elements, including the beam forming electrodes, the microwave interaction structure, the collector, and all electrical and microwave connections are printed on a pair of ceramic sheets. The sheets themselves form the vacuum envelope of the tube. Microwave power is generated by passing a sheet electron beam between the ceramic sheets. The beam interacts with the printed microwave structure on the sheets to generate power. The electron beam is formed by printed beam-forming electrodes from a strip cathode, which is the only nonprinted element inside the tube. The beam is focused through the microwave structure to the printed collector by a pair of sheet magnets mounted on the outer surface of the ceramic sheets. The objective performance requirements of the printed circuit traveling wave tube developed on this program were as follows: Pulsed Output Power 100W, Duty Cycle 10%, Frequency 9.5 to 10.5 GHz, Saturation Gain 30 dB, and Overall Efficiency 15%.