Journal ArticleDOI
Acoustic antennas for atmospheric echo sounding
F. F. Hall,J. W. Wescott +1 more
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A conical horn reflector antenna made of fiberglass has given excellent performance at 1-5 kHz after being coated with a viscous damping tar to keep reverberation time short for the reception of weak echoes as discussed by the authors.Abstract:
The successful utilization of acoustic waves for atmospheric echo sounding requires an efficient antenna, with high on‐axis gain and suppressed sidelobes. Existing microwave antennas and optical searchlights have been adapted for acoustic use, and their performance measured. A conical horn reflector antenna made of fiberglass has given excellent performance at 1–5 kHz after being coated with a viscous damping tar to keep reverberation time short for the reception of weak echoes with minimum delay following the transmission of 20 acoustic watts from the antenna. Septum dampers have been used successfully on parabolic dish antennas. Antenna beam patterns have been measured on an outdoor range, across a canyon, and the results agree closely with predictions from diffraction theory. Absorbing, cylindrical antenna enclosures have been found effective in reducing sidelobe reception by 10 to 20 dB, also in agreement with predictions. Attention to antenna design should provide unimpaired echo sounder operation in...read more
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Journal ArticleDOI
Advances in atmospheric acoustics
Edmund H. Brown,Freeman F. Hall +1 more
TL;DR: A detailed review of developments in atmospheric acoustics of the last decade is given in this paper, which includes new ways to use refractive effects, studies of phase and amplitude fluctuations during propagation of sound along a path, nonlinear effects near high-powered acoustic antennas, problems related to noise, insights into large-scale atmospheric processes gained from infrasound, applications dependent on the Doppler frequency shift, and hybrid devices using both acoustic and electromagnetic waves.
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Quantitative bistatic acoustic sounding of the atmospheric boundary layer
TL;DR: In this paper, the authors measured the magnitude of the structure parameters for wind and temperature, C and C respectively, using turbulence probes attached to the tethering cable of a large (1300m3) balloon.
Journal ArticleDOI
A quantitative comparison between acoustic sounder returns and the direct measurement of atmospheric temperature fluctuations
TL;DR: In this paper, it was shown that reasonably accurate estimates of the atmospheric temperature structure paparmeter CT 2 can be derived from the returns of a monostatic acoustic sounder in both stable and convective atmospheric conditions.
Sounder returns and the direct measurement of atmospheric temperature fluctuations
TL;DR: In this paper, it was shown that reasonably accurate estimates of the atmospheric temperature structure paparmeter C$ can be derived from the returns of a monostatic acoustic sounder in both stable and convective atmospheric conditions.
Journal ArticleDOI
Quantitative low-level acoustic sounding and comparison with direct measurements
TL;DR: In this paper, the first 150 m of the atmospheric boundary layer obtained by a high-frequency acoustic mini-sounder is compared with measurements obtained with a full complement of instruments including sonic anemometers mounted on the Boulder Atmospheric Observatory tower.