Date: Thu, 22 Apr 1999 07:20:57 -0400
From: "Holger 'Geri', DK8KW" <DK8KW@compuserve.com>
Subject: LF: Calculation of radiated power
To: rsgb_lf_group@blacksheep.org
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Hello Lowfers,

Dick wrote:

>Concluding I would say that the only reliable way of finding radiated
power is by measuring the field strength near the station. But preferably
at say 3 or 4 kilometers distance and not 1 km as I did so that correcting
for the near field component is not required.<

I understand the difficulties about measuring/estimating the ERP that Dick
has pointed out in his message. How about the relative measruement of
comparing the field stregth of a station with known ERP (or at least with
one where the ERP can be estimated with a reasonable accuracy, such as
DBF39 with 25 kW) and using the distance to those station to correct for
path losses using the CCIR curves? The sample in my previous message
comparing DF3LP and DBF29 is quite simple, especially the path-loss
calculation is simplified and maybe needs som emore attention. Rik, ON7YD
mentioned, that it was not 9 dB difference as I briefly calculated from the
difference in distance but only 4 dB according to the CCIR curves, so
DF3LPs ERP would be another 5 dB weaker than my anticipated 25 mW ...
acording to the figures stated by Peter I believe this to be too low?

Two questions in this respect:

1. Can someone point me to an internet page where to find those curves?
 
2. How do I use CCIR field strength attenuation in V/m to convert this into
voltage (e.g. in dBm) attenuation at the input of my receiver (75 Ohm)?   


Best 73

Geri, DK8KW (W1KW)