A. A. Shvetsov

A dual-wave atmosphere transparency radiometer of the millimeter wave range

The MIAP-2 radiometric complex intended for measuring the atmospheric absorption in the millimeter wavelength range (2 and 3 mm) is described. The complex is based on two solid-state modulation radiometers with wave ranges of 84–99 GHz and 132–148 GHz, which are equipped with horn-lens antennas. The device determines an optical depth in the millimeter wave range using the atmospheric-dip method and the absolute signal calibration method in the fully automated mode under the remote control via the Internet. A set of observations was performed in the stationary mode and in mountain expedition conditions. The reliability of the device was evaluated from 2-year operation results.

A microwave spectroradiometer for the earth-based complex for thermal sounding of the stratosphere

A laboratory model of the spectroradiometer for the complex for thermal sounding of middle atmosphere has been designed. Based on the self-radiation spectra of the atmosphere measured by this instrument in the frequency range of 52.45–53.20 GHz, it is possible to retrieve the vertical temperature profile in the stratosphere and the upper troposphere. The temperature profiles obtained in the test cycle of round-theclock observations in the altitude range of 10–55 km are in good agreement with the satellite data.

Ground-based microwave spectroradiometer for thermal sounding of the troposphere

The laboratory model of a mobile solid-state uncooled microwave spectroradiometer, operating in the frequency range of 50 to 55 GHz is described. It is designed for remote passive monitoring of the tropospheric temperature. The spectroradiometer consists of a heterodyne receiver with a low noise amplifier at input and 8-channel spectrum analyzer. To ensure the internal calibration of the intensity of the received atmospheric radio emission using the built-in unit type modulator-calibrator based on GaAs diodes with the Schottky barrier. The antenna system of the spectroradiometer consists of a teflon enlightened lens and conical corrugated horn. The device is equipped with an automated control system process measurement, calibration, and data pre-processing.

Improving the Efficiency of Single-Sideband Millimeter-Wave Reception by Returning the Signal Converted into Image

We describe the technique, apparatus, and the results of studies of the possibility of millimeter-wave single-sideband reception with minimum loss, associated with conversion into image. The single-sideband noise temperature of the receivers is improved by a factor of 1.4-1.9 in the N and Y bands.

Automated microwave radiometer for measuring the atmospheric ozone emission line

The work presents the results of upgrading of microwave spectroradiometer for ground-based remote sensing of Earth’s ozone layer improving essentially the noise temperature (up to value less 1500 K). For this, the low-noise high frequency amplifier was set up in front of the receiver and temperature control of the instrument was changed for stable work of the amplifier.

A calibration system for microwave radiometers based on a modulator–calibrator

A system for automatic internal calibration of millimeter-range radiometers is described. This system is based on an electrically controlled modulator–calibrator, which is a compact solid-state device that combines the functions of a modulator and a source of stable noise calibration signals. Stability of the calibration levels is provided by thermostatting the modulator–calibrator case and stabilization of the control currents. The calibration and data-collection process is governed by software using a special digital module and a personal computer.

Mixer conversion loss and receiver single-sideband noise temperature improvement by return of signal converted in image

A rather simple and low cost method of improving mixer conversion loss and the single side-band noise temperature of a receiver was proposed and implemented. As a result the single side-band noise temperature of uncooled receivers was reduced to 770 K at a frequency 115.3 GHz and to 1500 K at a frequency 210.5 GHz.