10.1 Exposure limits
(for personal safety)
For radio transmitters (including mobile phones/cell towers), internationally
approved exposure limits, but also various precautionary limits and recommen-
dations exist. Depending on the context and country, however, exposure limits
and recommendations differ vastly.
The
German
limits are defined by the “Regulierungsbehörde für Telekommuni-
kation und Post (Reg TP)”, a subsidiary of the “Bundesministerium für Wirtschaft
und Arbeit (BMWA)”. They are mainly based on the heat generation caused by
high-frequency fields. It is assumed that effects harmful to health only occur
when tissue warms by more than 1°C. These exposure limits are mostly accep-
ted by all national and international committees. For Germany, these limits are
recorded in the “Verordnung über elektromagnetische Felder (26. BlmSchV)”
and are mostly derived from the international recommendations. As an approval
for the compliance with these exposure limits, radio installations acquire the
“Reg TP Standortbescheinigung”.
The German exposure limits are designed for squared averages recorded over
intervals of 6 minutes
, and are categorized by frequency ranges. Depending
on the affected group of persons, different limits apply. As an example, we will
use the limit defined for the general population:
Frequency [MHz]
E field strength[V/m]
M field strength[A/m]
1 - 10
87 / f
0,73 / f
10 - 400
27,5
0,073
400 - 2.000
1,375 * f
0,0037 * f
2.000 - 300.000
61
0,16
This graphic shows a visual
representation of aforementioned
formulas over a frequency range
from 1Hz to 100GHz.
The graph
clearly shows that the simple,
wide-spread “broadband”
devices CANNOT measure and
evaluate exposure limits cor-
rectly as they are not frequen-
cy-dependent!
10.0 Exposure limits
37
Summary of Contents for SPECTRAN HF-2025
Page 72: ...23 0 For your notes 72...
