Low-noise receiver for microwave ozone measurements

Rozanov, S. B.; Zavgorodniy, A. S.; Логвиненко, С. В.; Lukin, A. N.; Shtanyuk, A. M.; Bol’shakov, Oleg

doi:10.1007/s11141-012-9325-9

Cited by 5 publications

(8 citation statements)

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“…Measured maximum value of the image band suppression by the SSB filter was as high as 34 dB near the image band centre at 134.625 GHz. Experimental estimate of total input signal loss including loss in the corrugated horn at the mixer flange was 0.8±0.5 dB [5].Local oscillator pump of the mixer at 138.4 GHz is provided by 34.6 GHz Gunn-diode oscillator following with two frequency doublers [7]. Cold (85 K) blackbody background was introduced to the signal beam through the SSB filter in the image band of the mixer to reduce its noise temperature for the signal band centered at 142.175 GHz.…”

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confidence: 99%

“…Elevation angle of antenna is selected at observations depending on weather conditions. Antenna pattern width is of 1.5° at -3 dB level [5].Room temperature heterodyne receiver [5] of the ozonometer is based on planar Schottky diode mixer [6, 7] and consists of optical and high-frequency blocks (Fig. 1, left).…”

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confidence: 99%

“…Cold (85 K) blackbody background was introduced to the signal beam through the SSB filter in the image band of the mixer to reduce its noise temperature for the signal band centered at 142.175 GHz. This resulted in approximately 100 K yield in SSB receiver noise temperature [5].The high-frequency block of the receiver [5] provides 1) main amplification of the signal at the IF1 and its conversion to frequency bands of the spectrum analyzers, 2) phase-locking of Gunn-diode oscillator and additional local oscillators, and 3) broadband square-law and synchronous detection of part of the signal in the IF1 band to measure averaged brightness temperature of sky around the ozone line. This 'broadband channel' values are used to calculate attenuation of stratospheric and mesospheric ozone spectra in the troposphere.…”

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confidence: 99%

“…Elevation angle of antenna is selected at observations depending on weather conditions. Antenna pattern width is of 1.5° at -3 dB level [5].…”

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confidence: 99%

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Transportable millimeter-wave spectrometer for monitoring of the atmospheric ozone

Rozanov

Shtanyuk

Bol’shakov

et al. 2013

2013 International Kharkov Symposium on Physics and Engineering of Microwaves, Millimeter and Submillimeter Waves

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Ozone is one of the most important minor gas constituents of the atmosphere. Global depletion of the protective ozone layer in the last decades accompanied with such anomalous events as ozone holes in Antarctic and Arctic [1, 2] requires reliable long-term monitoring of ozone and ozone-related minor atmospheric gases from both satellites and ground level. Ground-based millimeter-wave (MMW) monitoring of atmospheric ozone is low-dependent on weather conditions, covers broad altitude region from the lower stratosphere to mesosphere, and is possible in day and night time [3,4]. These features of MMW measurements provide their advantages over traditional optical methods (UV spectrometers and lidars) and ozone sondes.A new transportable MMW spectrometer for ground-based monitoring of vertical distribution of atmospheric ozone (ozonometer) was designed and built at the LPI in cooperation with a number of leading scientific institutes of Russia. The instrument measures broadened spectral line of the atmospheric ozone thermal emission centered at 142.175 GHz (wavelength of 2.1 mm). Vertical ozone distribution in the stratosphere and mesosphere over point of observations (altitudes 12-75 km, up to 95 km at night) may be retrieved from the spectral line contour using special mathematical methods [4].The ozonometer consists of low-noise receiver, acousto-optical and filter-bank spectrum analyzers and PC with special software. The instrument may be operated in both automatic and manual mode. General view of the ozonometer is shown at Fig. 1. At present the instrument is placed at the LPI in Moscow before window closed with thin radio transparent polyethylene film. Elevation angle of antenna is selected at observations depending on weather conditions. Antenna pattern width is of 1.5° at -3 dB level [5].Room temperature heterodyne receiver [5] of the ozonometer is based on planar Schottky diode mixer [6, 7] and consists of optical and high-frequency blocks (Fig. 1, left). Optical block includes input Gaussian quasioptics [8], the mixer and local oscillator, corrugated horns to launch Gaussian beams, preamplifier of the first intermediate frequency (IF1) 3.5…4.0 GHz, and control interfaces. Quasioptical units are flat antenna mirror, chopper wheel of 200 mm diameter, room-temperature (hot) calibration load periodically placed across the signal beam, liquid nitrogen cooled reference load with brightness temperature varying from 85 K to 295 K by rotating wire grid, single sideband (SSB) filter, path length modulator to avoid distortions from standing waves, diplexer to combine signal and local oscillator beams and filtering local oscillator noise, and off-axis elliptic and parabolic mirrors for focusing Gaussian beams. Diameters of all apertures were selected to be no less than 4.5 w , where w is parameter of field distribution across main Gaussian mode [8]. The chopper wheel switches the receiver input between sky and the reference load with frequency of 30 Hz. The SSB filter and diplexer are Martin-Puplett interferometers. Meas...

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confidence: 99%

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confidence: 99%

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confidence: 99%

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confidence: 99%

“…Elevation angle of antenna is selected at observations depending on weather conditions. Antenna pattern width is of 1.5° at -3 dB level [5].…”

mentioning

confidence: 99%