Content-Transfer-Encoding: 8bit
Message-ID: <5.1.0.14.0.20020724141345.00aa3bd8@gemini.herts.ac.uk>
Date: Wed, 24 Jul 2002 16:18:18 +0100
To: rsgb_lf_group@blacksheep.org,  dj2lf@darc.de,  markusvester@aol.com, 
 "Reg Edwards" <g4fgq.regp@btinternet.com>
From: "James Moritz" <j.r.moritz@herts.ac.uk>
Subject: LF: Re: Activity from Deutschlandfunk Antenna
In-reply-to: <3.0.5.32.20020724101244.00a54a30@pop3.esoterica.pt>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org
Sender: <majordom@post.thorcom.com>

Dear Walter, Markus and friends, Reg, LF Group,

Very pleased to work DJ2LF/P this morning, both on 136k and cross-band 
40m/136k. I was running the usual 1200W + inverted L at 9m on LF, plus an 
IC718 with a dipole on 40m.Their signal was 579 even when running 1W TX 
power, and was obviously very strong when running the full 200W.

I also measured the field strength using a 4m^2 single turn loop antenna 
with an SPM-19 selective level meter. Running full power, DJ2LF/P measured 
between 35dBuV/m and 36.5dBuV/m, about 60uV/m on average, in IO91VR. At a 
distance of 705km, this works out to 36W ERP over perfect, flat ground - 
using G4FGQ's grndwav3 program, and assuming "type 4" ground (this seemed 
the best compromise of the several choices available), ground & diffraction 
losses account for an additional 6.7dB, making the actual ERP 167W - this 
is within 0.5dB of the figure obtained by PA0SE.

If my ERP is about 400mW, turning the above calculations around gives my 
field strength in JN49ON as about 3uV/m, so reception there is actually not 
too bad.

For comparison, DCF39 on the same antenna measures as 57dBuV/m, at a 
distance of 828km, an ERP over perfect ground of 7.0kW. And assuming the 
same ground type as before, ground loss is 9dB, giving an actual ERP of 
55kW. I believe the usual figure quoted is 40kW, so agreeing within 1.5dB.

I calculated the antenna calibration factor simply from the area of the 
loop and the impedance levels, so as a further cross-check I also measured 
DCF39 using my ferrite rod measuring antenna, previously calibrated using a 
Helmholz coil set-up. This measured DCF 39 at 56.4dBuV/m, so only 0.6dB 
difference between two completely different measuring antennas, calibrated 
in different ways, which inspires a good degree of confidence.

So thanks to all in Donnebach; It looks like the DLF mast, our 
measurements, and Reg's software are all working well today. I look forward 
to hearing how things were at the TX end!

Cheers, Jim Moritz
73 de M0BMU