Recent development on terahertz spectroscopy and measurement with phase locked backward-wave oscillators

Discusses a really fast frequency scanning option for millimeter and submillimeter-wave synthesizers which opens as a consequence new possibilities for precise microwave measurements. This becomes possible due to development of synthesized radio frequency source with a discreteness of 0.03 Hz and switching time of about 200 ns without phase jumps. The source is based on 0-50 MHz direct digital synthesizer microchip. Frequency modulation by sine, square-wave, triangle, saw-tooth and other desired functions with precisely known frequency deviation and period of modulation is possible. The signal from the source is used as a reference in a phase detector of BWO PLL so the tube output radiation frequency follows the law of the radio source frequency change. Fast frequency scan/modulation without phase jumps of phase-locked BWO is available now within 0.2 GHz.