Combined sub mm TWT and BWO with Biplanar Interdigital Circuit

The goal is to build a prototype tunable, nominally one-Watt, signal source, centered at 650 GHz, comprised of a backward wave oscillator (BWO) that provides a signal that is amplified by a traveling wave tube (TWT). The BWO and the TWT are fabricated as a unit on the same substrate using silicon lithography and processes of chemical vapor deposition (CVD) of diamond that have been patented by GENVAC. The device is assembled using liquid crystal display fabrication concepts that have not previously been applied to the manufacture of vacuum electron devices. In conventional practice, the oscillator and amplifier would be fabricated as separate devices. There are significant advantages that result from combining them on one wafer in one package. There are obvious manufacturing economies obtained by fabricating the two devices in the same process and by building only one vacuum envelope. In addition, if the two were separate devices, there would be losses associated with passing through the BWO output coupler, the TWT input coupler, a connecting transmission line and two vacuum windows, which in total would be approximately 10 dB.