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Date: Sat, 30 Oct 2010 00:10:43 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <schaefer@iup.uni-heidelberg.de>
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References: <Pine.LNX.4.64.1010291457450.26567@paranoid.lipkowski.org> <4CCAE624.3080402@legal-medicine.de> <Pine.LNX.4.64.1010292254530.7134@paranoid.lipkowski.org>
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Subject: Re: LF: vlf experiments-numerical considerations
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Hi Jacek,

All very interesting, i cannot stop thinking about ;-)
Your plot_80km.png tells me that in 200 km distance (pretty close to=20
DF6NM/DJ2LF/DK6NI/DJ6LB), 2500 Hz is the most suitable frequency.

Compared to 8970 Hz, the signal shall be 20 =B5V stronger, about a factor=
=20
5 in field strength (~ 14 dB). This would mean, my signal would be much=20
stronger even if the losses due to a parallel capacitor would increase=20
by say 6 dB.

BTW, since i was out of resonance during the 5170 Hz test, the current=20
was just half the current which would be possible. This means my TX=20
power on 5170 Hz was just about 150 W! Anyway the S/N at OE3GHB was=20
about the same as on 6470 Hz where i have had the full power! So the=20
signal could have been 6 dB stronger!

So, if i would use the 300m kite and switch a parallel capacitor to the=20
loading coil, 3x the C of the kite wire (about 5 nF/ 30 kV), i could=20
resonate on 2.5 kHz (crazy!). Although just 1/4 of the coils current=20
would flow into the wire (< 12 dB losses) my signal would be stronger in=
=20
that region! Ah, i have forgotten the lower radiation resistance of the=20
300m wire on this frequency,ok...

Oh dear, should we really try a 2.5 kHz test?

Another idea: It would be most interesting in a test on the earth=20
antenna since there is no need to resonate it and the earth losses are=20
almost independent of frequency! If the frequency decreases, the skip=20
depth (and so the effective loop area) increases. This might partly=20
compensate the decrease of efficiency.Wow! I will prepare such a test=20
for the next week! :-)

73, Stefan/DK7FC



Am 29.10.2010 22:57, schrieb Jacek Lipkowski:
> On Fri, 29 Oct 2010, pws wrote:
>
>> Yes, I'm very interested, especially in the makefile since I'm having
>> trouble invoking the GCC against those code. More than 30 years ago=20
>> dealing
>> with Fortran - on a block heating station named PDP-10 ["."]
>
> the page with code and sample graphs is here:
> http://www.lipkowski.org/~sq5bpf/vlf/wavevlf/
>
> i've added a program that can be used to create data for graphs and=20
> example files for gnuplot to make graphs.  the code compiles under=20
> gfortran
>
> jacek