Hi Piotr, Nice to see your good work again. Do you think it would be
possible to present the plot with a logarithmic distance scale. It might
also be interesting to try dbuV/m for the strength axis??.
Alan G3NYK
----- Original Message -----
From: "Piotr Mlynarski" <[email protected]>
To: <[email protected]>
Sent: Monday, October 04, 2010 9:44 PM
Subject: Re: VLF: Re: DK7FC's 7th VLF kite experiment
Stefan Schäfer pisze:
> Wow!
> Dear VLF,
> This was very nice to read. So many messages and so many positive
> receptions. I am really impressed!
>
> *Many thanks to you all* who have been active on this day, watching on
> 8,97 kHz, the Dreamers Band :-)
>
> *We have a new world record of the maximum distanced reception on VLF
> (by amateurs): SQ5BPF at a distance of 904 km with excellent S/N.*
> Congratulations!! See attached picture.
>
> Thanks to Markus/DF6NM for QSP to the reflector. Sorry to Wolf/DL4YHF
> that i was not QRV on 2m CW but there were problems to that time (see
> below). Thanks to SQ5BPF for the positive SMS ;-) Thanks to the US and
> canadian stations who tried to receive the signal. It becomes more and
> more probably since the S/N values are impressive here in EU.
>
> Congratulations to all successful receiving stations, especially the
> new ones (on 8970 Hz) which are as far as i can see: Daniele Tincani,
> SQ5BPF, DD7PC, DF0WD, F1AFJ (683 km since my locator is/was JN49IS),
> F5WK (very impressive S/N 25 dB at 460km distance!), DL3ZID(463 km) :-)
Dear Stefan, VLF ,
Congratulations to you for ,again, your remarkable efforts, passion,
knowledge and skills resulting in another, world-wide acknowledged VLF
experiment.
Unfortunately, i was away from home by the time the experiments were
taking place so i could only read e-mails with rx reports and remarks.
I guess you recall some discussion about field strength ,propagation
models etc.. among some "Dreamers" which took place, here,
on this reflector, after your second/third vlf experiment. Paul
Nicholson has introduced us to a paper dealing with some theoretical
considerations
about EM waves travelling in earth-ionosphere waveguide:
http://dspace.mit.edu/bitstream/handle/1721.1/16973/53712465.pdf;jsessionid=995C2F2A8DC7FFC28D518D8FF1745D7C?sequence=1
I 've written fortran code based on egn. 5.2 of the above paper and i
have already presented some theoretical estimates
based on data taken from your previous experiments. Today, i present
another theoretical E-field strength estimate( attachment) based upon
your recent setup
i.e with assumed antenna current of 1 Amp and its vertical length of
200 meters. The height of ionosphere has been assumed to vary between 60
and 80 km
f = 8970 Hz. A separate, 'single point' calculation has also been made
for the tx-rx distance of 904 km
i.e. between you and Jacek,sq5bpf and the calculated effective field
values for 60,70,80 km of ionosphere height are: 3.32; 2.85; 2.49
respectively
(expressed in microVolts/m).
73, Piotr, sq7mpj
p.s.
in the course of collecting some literature dealing with propagation
models of EM waves in the ELF_VLF_LF range; 'receivers' and 'antennae'
i have found an interesting paper which title ( and contents) reads ( in
our,radioamateur vocabulary)
as simply another loop antenna and receiver for VLF reception :-)
http://www-star.stanford.edu/~vlf/publications/2010-02.pdf
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