Committee on Radio Astronomy Frequencies

The Committee on Radio Astronomy Frequencies (CRAF) is a committee of the European Science Foundation (ESF).

Frequency band allocated to the Radio Astronomy Service:

ITU-RR allocations (+ footnotes):

22    - 22.21  GHz:	FIXED
			MOBILE except aeronautical mobile
			
			5.149
			

22.21 - 22.5   GHz:	EARTH EXPLORATION-SATELLITE (passive)
			FIXED
			MOBILE except aeronautical mobile
			RADIO ASTRONOMY
			SPACE RESEARCH (passive)
			
			5.149 5.532
			
22.5  - 22.55  GHz:	FIXED
			MOBILE

National Arrangements for Radio Astronomy different from ITU-R Radio Regulations:

Astrophysical importance of the band 22.21 - 22.50 GHz

The 22.21 - 22.5 GHz "H2O-band" is one of the most important for spectroscopy in radio astronomy (See ITU-R Recommendation RA.314-8, table 1, and the IAU list of important spectral lines).

Threshold levels of interference detrimental to radio astronomy spectral-line observations:

System Sensitivity (noise fluctuations)Threshold Interference Levels
TemperaturePower Spectral DensityInput PowerPower Flux DensitySpectral Power Flux Density
Single Dish2.91 mK-254 dB(WHz-1)-210 dBW-162 dB(Wm-2)-216 dB(Wm-2Hz-1)

NOTE:

For further details the reader is referred to ITU-R Recommendation RA769. It should, however, be noted that the observed spectral power flux densities are much lower than the harmful interference levels because they are made in the main beam of the radio astronomy antennas whereas the harmful levels correspond to reception in the sidelobes, i.e. the differences are related to the gain of the antennas. The differences can be of the order of 50 to 80 dB W m-2 Hz-1 (see ITU-R "Handbook on Radio Astronomy", 1995/2003, chapter 4).

In Europe, the band 22.21 - 22.50 GHz is used by the Radio Astronomy Service in:

Threats to the Radio Astronomy Service:

Last modified: March 16, 2005