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Hello Dick:
I took a plot, last month, of the
transmission of a Spanish colleague, who is in Madrid, at 500 km as well, and
the signal level during the day was not stable, varying around 3 or 4 dB; I
guess that the D layer reflection for this range is not low.
On the other hand, Dick , I think that the mean
soil conductivity for your path , in my modest opinion, should be lower than
0.01 S/m, taking into account the conductivity map that can be seen in the
Geri´s page.
I agree with you that, for this 500 km range, there
is high uncertainty in the determination of radiated power.
73 de José, EA1PX
----- Original Message -----
Sent: Monday, May 15, 2006 2:11 PM
Subject: Re: LF: DCF39 ERP and field
strength
Dear Jose,
You wrote:
In the web of Geri, DK8KW, can be seen that DCF39 ERP is 40KW (22KW
EMRP), based on measurements made by Geri some years ago. For this radiater
power corresponds, at 1800 Km, in function of inverse of distance, 58
dB(uV/m); last nigth I made measurement of 60 dB(uV/m), so I wonder if still
DCF39´s power is the same as before, and if the previous theorical field
strength, with no reflection loss, can be exceeded some times due to the
several propagation factors involved.
I measure the
field strength of DCF39 at 2078 microvolt/metre (66.35 dBµV) , as it is
always at daytime.
The distance between my location and
DCF39 is about 500 km. Using the graph for "LAND" (conductivity 0.03 S/m,
dielectric constant 40) in CCIR Recommandation 368-7: GROUND-WAVE
PROPAGATION CURVES FOR FREQUENCIES BETWEEN 10 KHz AND MHz I find the power
of DCF39 to be 39.8 kW. This should be rounded to 40 kW of course.
That this agrees so well with the 40 kW mentioned by Geri is pure
coincidence, given the uncertainties involved.
73, Dick, PA0SE
JN22GD
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