DK8KW Longwave Information
Field Strength Profile of
On April 8, 2000, Gamal he and myself took a nice ride to the
Burg transmitter facility, took some pictures and a field strength profile
from the location back to my home QTH, approximately 120 km away.
As DCF39 is one of the few LF signals that has been heard on the other
side of the atlantic, it might be interesting for further field strength
40 kW ERP (see below).
calculations to know the ERP. With our measurements with an untuned
1m-diameter loop and a calibrated level meter (MV61,
as my Siemens D2108 gave up its work) we came to the result, that the 50
kW DCF39 signal on 138.830 kHz mark frequency is being transmitted from
a 325m high antenna. The actual ERP we came up with (matching the appropriate
CCIR-curves with a very good correlation) is
So for all you guys in Canada or the U.S. that are able to hear DCF39,
you might consider this ERP in relation to an amateur signal of only 1
W ERP (but maybe 1000 km closer to you location if it is a UK or Irish
The 40 kW estimation is based on calculations made by Veino (OH2LX)
and also on the curves derived from the CCIR- RECOMMENDATION 368-7 named
"GROUND-WAVE PROPAGATION CURVES FOR FREQUENCIES BETWEEN 10 kHz AND 30 MHz".
The recommendation contains curves from 30 kHz to 30 MHz, based on various
conductivity values. As no 136 kHz is available, we have selected the 150
kHz curve instead. The curve shows the expected field strength for a 1
kW signal vs. distance.
The conductivity can be derived from the following map. The area we
used for our measurments has an average conductivity of approx 6 mS/m.
Courtesy of Telefunken Sendertechnik Berlin
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