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)
• National Arrangements for Radio Astronomy different from ITU-R Radio Regulations
• Astrophysical importance of the band 134 - 136 GHz
• Threshold levels of interference detrimental to radio astronomy
• Radio Astronomy use of this band in Europe
• Threats to the Radio Astronomy Service

ITU-RR allocations (+ footnotes):

130 - 134 GHz:		EARTH EXPLORATION-SATELLITE (active)  5.562E
			FIXED
			INTER-SATELLITE
			MOBILE  5.558
			RADIO ASTRONOMY
		
			5.149 5.562A


134 - 136 GHz:		AMATEUR
			AMATEUR-SATELLITE
			Radio astronomy


136 - 141 GHz:		RADIO ASTRONOMY
			RADIOLOCATION
			Amateur
			Amateur-satellite
			
			5.149

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

• Armenia: no allocation
• Liechtenstein: no allocation
• Russian Federation: no allocation

Astrophysical importance of the band 134 - 136 GHz

This frequency band is used for both spectral line and continuum observations.

See also: mm-Wavelength Astronomy.

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

	System Sensitivity (noise fluctuations)		Threshold Interference Levels
	Temperature	Power Spectral Density	Input Power	Power Flux Density	Spectral Power Flux Density
Single Dish	2.74 mK	-254 dB(WHz-1)	-204 dBW	-140 dB(Wm-2)	-200 dB(Wm-2Hz-1)

Threshold levels of interference detrimental to radio astronomy continuum observations:

	System Sensitivity (noise fluctuations)		Threshold Interference Levels
	Temperature	Power Spectral Density	Input Power	Power Flux Density	Spectral Power Flux Density
Single Dish	0.037 mK	-273 dB(WHz-1)	-185 dBW	-121 dB(Wm-2)	-219 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 134 - 136 GHz is used by the Radio Astronomy Service in:

• Spain

Threats to the Radio Astronomy Service:

Sharing problems with the following services:

• Amateur Service
• Amateur-Satellite Service

  Out-of-band emission from the following services:

• Earth Exploration-Satellite Service
• Fixed Service
• Inter-Satellite Service
• Mobile Service
• Radiolocation Service