RADIO ASTRONOMY FREQUENCY ALLOCATIONS

This section shows frequencies allocated for radio astronomy in the European Union. This is by international agreement. Certain scientifically important frequency bands are kept clear of radio transmissions, allowing radio astronomers to detect the faint signals from cosmic sources.

In practice, there is still some interference. Some of these frequency bands are close in frequency to legal, high power transmitters.  High signal levels out of the radio astronomy bands can still desensitize radio telescope receivers. All practical transmitters also radiate a small fraction of power away from their allocated frequencies, called 'spurious' signals. These spurious signals are very small, but still many times larger than the signals radio astronomers are trying to detect. For these reasons the most sensitive radio telescopes are as far away from civilization as possible and normally make use of very good filters.

Radio Astronomy frequency allocations don't mean that you can ONLY use these frequencies for radio astronomy. Any frequency for which the atmosphere is transparent can be used. The problem is that other frequencies are assigned to other services which might cause interference to your radio telescope. The 88 - 108 MHz FM broadcast band is a good example of this.

Jupiter's most interesting radiation is between about 15Mhz and 30MHz. In this range there is only one very small, officially allocated band. To study Jupiter's radiation in this band, the radio astronomer has to contend with transmissions from all over the world as well as computer- and television interference. The radio astronomer is forced to work outside the allocated frequency range and has to learn to distinguish between all kinds of noise and that coming from Jupiter.

In most cases, interesting frequencies have been set aside for radio astronomy. This is thanks to the hard work of radio astronomers through the years to keep these frequencies clear of terrestrial and satellite transmissions. In future their work will become harder as commercial demands on frequency usage make it very difficult for regulators to justify allocating frequencies for scientific purposes.


Table of frequency allocations for European radio astronomers:

Frequency band
Designation
Radio astronomy use
Comments
13.36 - 13.41 MHz
HF


25.55 - 25.67 MHz
HF


37.5 - 38.25 MHz
VHF
Continuum observations

73 - 74.6 MHz
VHF
  1. Solar wind observations.
  2. Continuum observations.

150.05 - 153 MHz
VHF
  1. Continuum observations.
  2. Pulsar observations.
  3. Solar observations.

322 - 328.6 MHz
UHF
  1. Continuum observations.
  2. VLBI

406.1 - 410 MHz
UHF
  1. Continuum observations.
  2. Pulsar observations.

608 - 614 MHz
UHF
  1. Continuum observations.
  2. VLBI

1400 - 1427 MHz **
L-band
Spectral line observations
21cm hydrogen line
1660 - 1660.5 MHz
L-band
VLBI

1660.5 - 1668.4 MHz
L-band
  1. VLBI
  2. Line observations.
  3. Continuum observations.

1668.4 - 1670 MHz
L-band


1718.8 - 1722.2 MHz
L-band


2655 - 2690 MHz
S-band
Continuum observations

2690 - 2700 MHz
S-band


3260 - 3267 MHz
S-band


3332 - 3339 MHz
S-band


3345.8 - 3352.5 MHz
S-band


4800 - 4990 MHz
 C-band
Continuum observations

4990 - 5000 MHz
C-band
  1. Continuum observations.
  2. VLBI

5000 - 5030 MHz
C-band
VLBI

6650 - 6675.2 MHz
C-band


10.6 - 10.68 GHz
X-band
  1. Continuum meausurements.
  2. VLBI

10.68 - 10.7 GHz
X-band
  1. Continuum observations.
  2. VLBI

14.47 - 14.5 GHz
Ku-band
  1. Spectral line observations.
  2. VLBI

15.2 - 15.35 GHz
Ku-band
VLBI

15.35 - 15.4 GHz
Ku-band
  1. Continuum observations.
  2. VLBI

22.01 - 22.21 GHz
Ka-band
Spectral line observations
Water line.
22.21 - 22.5 GHz
Ka-band
Spectral line observations
Water line.
22.91 - 22.86 GHz
Ka-band
Spectral line observations
  1. Methyl Formate
  2. Ammonia
23.07 - 23.12 GHz
Ka-band
Spectral line observations

23.6 - 24.0 GHz
Ka-band
  1. Spectral line observations
  2. Continuum observations
Ammonia line
31.2 - 31.3 GHz
Ka-band
Continuum observations

31.3 - 31.5 GHz
Ka-band
Continuum observations

31.5 - 31.8 GHz
Ka-band
Continuum observations

36.43 - 36.5 GHz
Ka-band
Spectral line observations
  1. Hydrogen cyanide
  2. Hydroxil
42.5 - 43.5 GHz
Q-band
Spectral line observations
Silicon monoxide and many other lines.
48.94 - 49.04 GHz
Q-band
Spectral line observations
Carbon monosulphide
51.4 - 54.25 GHz
V-band


58.2 - 59 GHz
V-band


72.77 - 72.91 GHz
V-band
Spectral line observations
Formaldehyde line.
86 - 92 GHz
W-band
  1. Spectral line observations.
  2. Continuum obserations.

92 - 94 GHz

Spectral line observations.
Diazenylium and many other lines.
95 - 100 GHz

  1. Spectral line observations.
  2. Continuum observations.


** Note that frequencies above 1GHz (1000MHz) are collectively referred to as microwave frequencies. Microwave frequencies are further classified as L-band, S-band, C-band, etc.


References

  1. Frequency range 29.7 MHz to 105 GHz and associated European table of frequency allocations and utilisations. June 1994. Revised March 1995 and February 1998.
  2. Table of frequencies allocated to radio astronomy, the  Earth exploration satellite, and space research.  http://www.aoc.nrao.edu/vla/html/rfa.htm
  3. Basics of Space Flight - Chapter 6: Electromagnetic phenomena. http://www.jpl.nasa.gov/basics/bsf6-3.html