15.4 TV and radio broadcast towers
TV and radio broadcast towers are a relic from the “stone
age” of information transmission. They are among the
strongest radiation sources in existence. The highest
transmitting powers are used by TV broadcast stations,
which may employ more than 1000kW! (for comparison: a
cell tower uses about 40 watts=0,04kW). Short wave radio
stations employ transmitting powers of up to approx.
600kW. FM radio broadcast, employing approx. 100 kW,
are already “more conservative” in this respect. Recently,
these are being converted to digital standards (DVB-T and
T-DAB).
Seeing the enormous transmitting powers involved, it is
not surprising that close to these stations (approx. 100m),
even the extremely high official exposure limits are excee-
ded.
15.5 Satellites
Satellites are gaining an ever-increasing importance for
information transmission nowadays. They orbit the earth at
a height of approx. 36000 km in a geostationary orbit. Even
though these satellites employ a “high” transmitting power
in the high GHz range, the radiation exposure on earth is
so extremely low due to the vast distance that you need
the well known dish antennas seen everywhere to focus
the radiation like a lens. These dish antennas and the cor-
responding LNB receivers do not(!) radiate, in contrast to
popular misconceptions. They are completely passive
reception devices. Thus, satellite technology only causes a
very low amount of radiation exposure. If at all, the recei-
ver may cause radiation as it amplifies and converts sig-
nals for later sending them to the TV. For measuring
this
radiation, you additionally need an LF measurement devi-
ce from the SPECTRAN series.
Stone-age technology:
Thousands of these bro-
adcast towers are in
operation.
Modern and almost
exposure-free: Informati-
on transmission via
satellites.
15.0 RF exposure in practice
55
Содержание SPECTRAN HF-2025
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