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 31.2 - 31.8 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):

31    -  31.3  GHz:	FIXED 5.543A
			MOBILE
			Standard Frequency and Time Signal-Satellite
				(space-to-Earth)
			Space Research  5.544 5.545
			
			5.149
			
			
31.3  - 31.5   GHz:	EARTH EXPLORATION-SATELLITE (passive)
			RADIO ASTRONOMY
			SPACE RESEARCH (passive)
			
			5.340
			
			
31.5  - 31.8   GHz:	EARTH EXPLORATION-SATELLITE (passive)
			RADIO ASTRONOMY
			SPACE RESEARCH (passive)
			Fixed
			Mobile except aeronautical mobile
						
			5.149 5.546
			

31.8  -  32    GHz:	FIXED 5.547A
			RADIONAVIGATION
			SPACE RESEARCH (deep space)(space-to-Earth)
			
			5.547 5.547B 5.548			
			
						

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

• Armenia: no allocation in the band 31.2-31.3 GHz
• Estonia: no allocation but No. 5.340 applies to the band 31.3-31.5 GHz
• Liechtenstein: no allocation but No. 5.340 applies to the band 31.3-31.5 GHz
• Luxembourg: no allocation
• Russian Federation: no allocation in the band 31.2-31.3 GHz
• Turkey: no allocation in the band 31.2-31.3 GHz

Astrophysical importance of the band 31.2 - 31.8 GHz:

The band 31.2 - 31.8 GHz is a continuum band of sufficient width. The allocations to other services in the band 31.5 - 31.8 GHz should not lead to difficulties. The provisions of No 5.149 and 5.340 should be sufficient to provide satisfactory local protection for observatories.

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	0.083 mK	-269 dB(WHz-1)	-192 dBW	-141 dB(Wm-2)	-228 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 31.2 - 31.8 GHz is used by the Radio Astronomy Service in:

• Germany
• Italy
• Sweden
• United Kingdom

Threats to the Radio Astronomy Service:

Out-of-band emission from the following services:

• Fixed Service
• Mobile Service
• Radionavigation Service
• Space Research Service