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 51.4 - 54.25 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):

50.4  -  51.4  GHz:	FIXED
			FIXED-SATELLITE (Earth-to-space)	
			MOBILE
			Mobile-Satellite (Earth-to-space)
			
			
51.4  -  52.6  GHz:	FIXED
			MOBILE
			SPACE RESEARCH (passive)
			
			5.547 5.556
			
			
52.6  -  54.25 GHz:	EARTH EXPLORATION-SATELLITE (passive)
			SPACE RESEARCH (passive)
			
			5.340 5.556
			
			
54.25 -  55.78 GHz:	EARTH EXPLORATION-SATELLITE (passive)
			INTER-SATELLITE 5.556A
			SPACE RESEARCH (passive)
			
			5.557A

			
55.78 -  56.9  GHz:	EARTH EXPLORATION-SATELLITE (passive)
			FIXED
			INTER-SATELLITE 5.556A
			MOBILE 5.558
			SPACE RESEARCH (passive)
			
			5.547 5.557
			

56.9  -  57    GHz:	EARTH EXPLORATION-SATELLITE (passive)
			FIXED
			INTER-SATELLITE 5.556B
			MOBILE 5.558
			SPACE RESEARCH (passive)
			
			5.547 5.557

			
57    -  58.2  GHz:	EARTH EXPLORATION-SATELLITE (passive)
			FIXED
			INTER-SATELLITE 5.556A
			MOBILE 5.558
			SPACE RESEARCH (passive)
			
			5.547 5.557
			

58.2  -  59    GHz:	EARTH EXPLORATION-SATELLITE (passive)
			FIXED
			MOBILE
			SPACE RESEARCH (passive)
			
			5.547 5.556
			

59    -  59.3  GHz:	EARTH EXPLORATION-SATELLITE (passive)
			SPACE RESEARCH (passive)
			FIXED
			INTER-SATELLITE 5.556A
			MOBILE 5.558
			RADIOLOCATION 5.559
			
			
59.3  -  64    GHz:	FIXED
			INTER-SATELLITE
			MOBILE 5.558
			RADIOLOCATION 5.559

			5.138

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

• Austria: primary allocation in the bands 51.4 - 54.25 GHz and 58.2 - 59 GHz
• Ireland: allocation in the bands 51.4 - 54.25 GHz and 58.2 - 59 GHz
• Italy: primary allocation in the band 52.6 - 55.78
• Norway: primary allocation
• Poland: primary allocation in the bands 51.4 - 54.25 GHz and 58.2 - 59 GHz
• Switzerland: primary allocation in the bands 51.4 - 54.25 GHz and 58.2 - 59 GHz

Astrophysical importance of the band 51.4 - 54.25 GHz

The band 51.4 - 54.25 GHz is an important radio astronomy band in the series of continuum bands.

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	3.00 mK	-254 dB(WHz-1)	-207 dBW	-152 dB(Wm-2)	-209 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 51.4 - 54.25 GHz is not used by the Radio Astronomy Service by terrestrial stations.

Threats to the Radio Astronomy Service:

Sharing problems with the following services:

Out-of-band emission from the following services: