Knowledge Bank

Extension of the microwave spectroscopy frequency range up to 1.5 Terahertz achieved by frequency multiplication of the submillimeter Backward Wave Oscillator (BWO) of 300 GHz range up to the fifth harmonic on the multiplier developed using planar Schottky diode is reported [1, 2]. Spectroscopic cell with acoustic detector had been used for selection and detection of harmonics by observation of proper spectral lines of gases. $SO2$ lines in the range 541 - 1524 GHz were observed in the second, third, fourth and fifth harmonics of BWO fundamental frequency. Ways to the further significant extension of microwave spectroscopy range are shown.