Radiometer of the 3-mm wave range with a modulator-calibrator

Abstract

We describe a radiometer intended for use in the spectroradiometric complex for remote sensing of the Earth's atmosphere. The main feature of the radiometer is application of an electrically controlled modulator-calibrator allowing one to perform measurements and thermal calibration in a wide temperature range without using matched loads and means for their connection. The principle of operation and design of the modulator-calibrator are described and the characteristics of the radiometer and its separate units are presented.

Quasioptical low-inertia radiation detector as a noise generator

“…As a result of the measurements using superheterodynes [1,8], it is shown that at a frequency of 115 GHz, the effective temperature of radiation from the large aperture of the developed device varies from room temperature to 650 K (see Fig. 3) as a current from 0 to 3 mA flows via the diode matrix.…”

“…The effective temperature decreases almost monotonically with increasing frequency to almost 310 K for a current of 3 mA in the region of 300 GHz. The effective temperature drop to below room temperature, which was observed for small currents in the SBD modulator-calibrators [1][2][3], was not observed in the described case of the δ-doped diodes.…”

“…Effective radiation temperature of the studied device was measured with the help of superheterodyne receivers [1,8] with calibration by two "black bodies" at room temperature and boiling nitrogen temperature, respectively.…”

“…Another advantage of the SBD-based crystal detectors is their possible use as noise radiation generators, which was already realized in [1][2][3] during calibration of the receiving equipment without using conventional gas-discharge and avalanche-type noise generators or different-temperature matched loads and their connection devices.…”

Microwave spectroradiometer complex for remote study of the stratosphere thermal structure

“…To this end, an electrically controlled device for internal calibration of the spectroradiometer (modulator-calibrator) developed at the Institute of Applied Physics of the Russian Academy of Sciences in cooperation with the "NIIPP" Company was included between the antenna and the receiver [9]. This device ensures antenna connection to the receiver input with a loss of about 0.5 dB (for a zero current) or input of the noise calibration signal depending on the current through the circuits of Schottky-barrier diodes (SBDs) built in the waveguide section.…”