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 36.43 - 36.5 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):

35.5  -  36    GHz:	EARTH EXPLORATION-SATELLITE (active)
			METEOROLOGICAL AIDS
			RADIOLOCATION
			
			5.549 5.551A
			
			
36    -  37    GHz:	EARTH EXPLORATION-SATELLITE (passive)
			FIXED
			MOBILE
			SPACE RESEARCH (passive)
			
			5.149
			
			
37    -  37.5  GHz:	FIXED
			MOBILE
			SPACE RESEARCH (space-to-Earth)

			5.547
			

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

• Armenia: no allocation or reference to No. 5.149
• Belgium: no allocation or reference to No. 5.149
• Estonia: no allocation or reference to No. 5.149
• Finland: primary allocation
• Italy: "footnote" secondary allocation
• Liechtenstein: no allocation or reference to No. 5.149
• Luxembourg: no allocation or reference to No. 5.149
• Norway: secondary allocation
• Poland: secondary allocation
• Russian Federation: no allocation or reference to No. 5.149
• Spain: no allocation or reference to No. 5.149
• Sweden: notification of use
• Switzerland: secondary allocation

Astrophysical importance of the band 36.43 - 36.5 GHz

The band 36.43 - 36.5 GHz is of importance for the search for HC₃N and OH lines. The sharing situation as it is now and the provisions of No. 5.149 should be sufficient to provide satisfactory local protection for observatories.

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	2.86 mK	-254 dB(WHz-1)	-207 dBW	-153 dB(Wm-2)	-210 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 36.43 - 36.5 GHz is used by the Radio Astronomy Service by:

• Finland
• Germany
• Italy
• Russia
• Sweden

Threats to the Radio Astronomy Service:

Sharing problems with the following services:

• Fixed Service
• Mobile Service

  Out-of-band emission from the following services:

• Fixed Service
• Mobile Service
• Radiolocation Service
• Space Research Service