Accession Number : AD0720869

Title :   Temporal Frequency Spectra of Multifrequency Waves in a Turbulent Atmosphere.

Descriptive Note : Technical rept.,

Corporate Author : WASHINGTON UNIV SEATTLE DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Ishimaru,Akira

Report Date : NOV 1970

Pagination or Media Count : 47

Abstract : General formulations for temporal frequency spectra of the fluctuations of plane, spherical and beam waves operating at two frequencies are given based on weak turbulence and frozen-in assumptions. The cross spectra and the coherence are obtained for the amplitude at two frequencies, the phase at two frequencies, and the amplitude at one frequency and the phase at another frequency. The results are examined in detail for a plane wave case. For the spectrum of the index of refraction Rappa to the -nth power in the inertial subrange, the amplitude spectrum behaves as K to the power((5-n)/2) for omega approaches zero and (k squared)(omega to the power (1-n)) for omega approaches infinity. The phase spectrum for omega approaches zero and for omega approaches infinity behaves as (k squared)(omega to the power (1-n)) with different constants. These results agree well with the experimental work of Janes, Thompson, Smith, and Kirkpatrick at 9.6 GHz and 34.5 GHz, and explains the ratio of the spectra at two frequencies. Also noted is the experimental slope of -2.6 as omega approaches infinity which may be compared with 1 - n = -2.66 using the Kolmogorov spectrum of n = 11/3. (Author)

Descriptors :   (*MICROWAVES, WAVE PROPAGATION), (*WIND, MEASUREMENT), MILLIMETER WAVES, ATMOSPHERIC MOTION, RADIO TRANSMISSION, CORRELATION TECHNIQUES, VELOCITY

Subject Categories : Meteorology
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE