Natural Noise Above 50 MHZ from Terrestrial and Extraterrestrial Sources

  • E. K. Smith
  • W. L. Flock


This paper offers a brief overview of natural radio noise for frequencies above 50 MHz in terms of brightness temperature as observed from two vantage points. The first is from an Earth station located at 40 degrees north latitude and observing at elevation angles from 0 to 90 degrees with an ideal antenna. The second is a satellite in geostationary orbit communicating with the Earth.

Earth station noise at VHF and UHF is dominated by galactic and solar noise. Emission from the atmosphere, gases and hydrometeors, are dominant at EHF and SHF. Radiative transfer theory is invoked in the calculation of brightness temperature from the atmosphere.

The situation is not vastly different from geostationary orbit if communications is with the Earth. Emission from the land and sea, even under idealized conditions, enters significantly. Land is a much more effective emitter than sea water, but at frequencies above 30 GHz the differential becomes much less due to the increasing significance of atmospheric emission.


Spectral Index Brightness Temperature Noise Power Antenna Temperature Natural Noise 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Kraus, J. D. (1988) Radio Astronomy, 2nd Edition, Cygnus.Quasar Books, Powell, Ohio.Google Scholar
  2. 2.
    Spaulding, A. D. & Hagn, G. H. (1978) Worldwide minimum radio noise levels (0.1 Hz to 100 Ghz), Effect of the ionosphere on Space and Terrestrial Systems, J. M. Goodwin, Ed., ONR7NRL, Arlington, VA, Jan. 24–26, 1978.Google Scholar
  3. 3.
    CCIR (1986b) Report 670, Worldwide external noise levels, 0.1 Hz to 100 GHz,Vol. 1, Spectrum Utilization and Monitoring, Recommendations and Reports of the CCIR, XVIth Plenary Assembly, Dubrovnik, 1986, ITU, Geneva.Google Scholar
  4. 4.
    Smith, E. K. (1982) The natural radio noise environment, Proc. IEEE Int’l Sympon EMC, Santa Clara, CA, Sept. 6–8, 1982., pp 266–277Google Scholar
  5. 5.
    CCIR (1986a) Report 720-2, Radio emission from natural sources in the frequency range above about 50 MHz, Vol. 5, XVI Plenary Assembly, Dubrovnik, 1986, ITU Geneva.Google Scholar
  6. 6.
    CCIR (1990) Recommendations and Reports of the CCIR, XVII’th Plenary Assembly, Dusseldorf, 1990, ITU, Geneva.Google Scholar
  7. 7.
    Boischot, A. (1975) Les Bruits Cosmiques, AGARD Conference on Electromagnetic Noise, Interference, and Compatibility, NATO, November, 1975.Google Scholar
  8. 8.
    Taylor, R. E. (1973) 136 MHz/400 MHz radio-sky maps, Proc. IEEE, Vol. 61, No. 4, pp 469–472.Google Scholar
  9. 9.
    Yates, K. W. & Wielebinski, R. (1966) Intensity-frequency dependence of the radio sky background, Australian J. Phys, Vol. 19, pp 389–407.Google Scholar
  10. 10.
    Allen, C. W. (1947) Interpretation of electron densities from coronal brightness, Mon. Not. Roy. Astron. Soc, vol. 107, p 426.Google Scholar
  11. 11.
    Berman, A. L. (1979) A unified observational theory for solar wind columnar turbulence, Deep Space Network Progress Report 42–50, pp 743–808, NASA-JPL, Caltech Jet Propulsion Laboratory, Pasadena, CA 91109.Google Scholar
  12. 12.
    Shimabukuro, F. I. (1988) The solar spectrum above 1 mm. The Solar Output and Its Variation, O. R. White, Ed., Colorado Associated University Press, Boulder, Colorado.Google Scholar
  13. 13.
    Hey, J. S. (1946) Solar radiation in the 4 and 6 meter radio wavelength band, Nature, Vol. 157, p 47.CrossRefGoogle Scholar
  14. 14.
    Smerd, S. F. (1950) Radio frequency radiation from the quiet sun, Australian J. Sci. Res, Vol. 3A, pp 34–59.Google Scholar
  15. 15.
    Covington, A. E. (1979) Historical background of the 1970 absolute calibration of solar flux density, Herzberg Institute of Astrophys, Rept. ARO-6, NRC No. 17686.Google Scholar
  16. 16.
    Mayer, C. H. (1964) Thermal radiation from the Moon and planets, IEEE Trans. Ant. & Propag. Vol. AP-12, pp 902–913.CrossRefGoogle Scholar
  17. 17.
    Waters, J. W. (1976) Absorption and Emission by atmospheric gases, Methods of Experimental Physics, Vol. 12B, Radio Telescopes, Ed. M. L. Meeks, pp 142–176, Academic Press, New York, N.Y.Google Scholar
  18. 18.
    Smith E. K., & Waters, J. W. (1981) Microwave attenuation and brightness temperature due to atmospheric oxygen and water vapor, JPL Publication 81–81, Aug. 15, 1981.Google Scholar
  19. 19.
    Smith, E. K. (1982) Centimeter and millimeter wave attenuation and brightness temperature due to atmospheric oxygen and water vapor, Radio Science, Vol. 17, No. 6, pp 1455–1464.CrossRefGoogle Scholar
  20. 20.
    Zavody, A. M. (1974) Effect of scattering by rain on radiometer measurements at millimeter wavelengths, Proc. IEE, Vol. 121, pp 257–263.Google Scholar
  21. 21.
    Tsang, L., Long, J. A, Njoku, E. G. Staelin, D. H. & Waters, J. W. (1977) Theory of microwave thermal emission from a layer of cloud or rain, IEEE Trans. Ant. & Propag. Vol. AP-25, No. 5, pp 650–657.CrossRefGoogle Scholar
  22. 22.
    Slobin, S. D. (1982) Microwave noise temperature and attenuation of clouds: statistics of these effects at various sites in the United States, Hawaii and Alaska, Radio Science, Vol. 17, No. 6, pp 1443–1454.CrossRefGoogle Scholar
  23. 23.
    Njoku, E. G. & Smith, E. K. (1985) Microwave antenna temperature of the Earth from geostationary orbit, Radio Science, Vol. 20, No. 3, pp 591–599.CrossRefGoogle Scholar
  24. 24.
    Smith, E. K. and Njoku, E. G. (1985) The microwave noise environment at a geostationary satellite caused by the brightness of the Earth, Proc. IEEE Int’l Symp. on EMC, Wakefield MA, Aug. 20–22, 1985, pp 318–323.Google Scholar

Copyright information

© Springer-Verlag Tokyo 1991

Authors and Affiliations

  • E. K. Smith
    • 1
  • W. L. Flock
    • 1
  1. 1.NASA Propagation Information Center, Department of Electrical and Computer EngineeringUniversity of ColoradoBoulderUSA

Personalised recommendations