P BAND
Satellite Communications Glossary
Satellite Communications — Satellite Frequencies — P Band
Information on P Band
P Band: 0.2-1.0 GHz. Because lower frequencies are trapped
by the ionosphere, only frequencies above 100 MHz are available
for satellite communications. The VHF and UHF range is principally
used for mobile satellite communications because the design of the
satellite and terminal hardware is relatively straightforward and well understood.
For example, the receive antenna can be a simple Yagi
or wire helix. The size and cost of terminals can
also be reduced by using higher powers that are easier
to generate on board the satellite because of the low
frequency being used. The propagation of the longer wavelengths is
also useful because they diffract more easily around obstacles and
are able to penetrate buildings.
The main restriction in the
use of these relatively low frequencies is the competition provided
by a large number of existing terrestrial radio applications in
these bands, which restricts the frequency range available for satellite
communications. A small frequency range and the power available from
a simple antenna mean that the capacity available in P
band is also very small--of the order of a
few to tens of channels with data rates of a
few kilobits per second (compared with tens of thousands of
channels available in C band, for example). The use of
simple antennas also produces a broad beamwidth, which tends to
require satellites to be located further apart to avoid interference.
Other topics in our resources on Satellite Communications related to P Band include:
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