From: "Ko Versteeg" <nl9222tv@tref.nl>
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: AMRAD Antenna ?
Date: Sat, 8 Jan 2000 15:15:16 +0100
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Sorry but i forgot to include this fine program,
found at:
http://ham.te.hik.se/~sm5bsz/pcdsp/pcdroot.htm
Worked with my PCI-64 and now works with AWE-64.

73's de  Ko,  NL9222.     JO22KF

----------
> From: g3kev <g3kev@netscapeonline.co.uk>
> To: rsgb_lf_group@blacksheep.org
> Subject: Re: LF: Re: AMRAD Antenna ?
> Date: Saturday, January 08, 2000 10:42 PM
> 
> Hello All.
> Your comment about your antenna maybe operating like a LOOP is probably
correct.
> I would suggest it is performing like a grounded quad. Similar systems
used on 160
> and 80 metres where one cannot get a full size quad up.
> At 1600 ft long and 50 ft high, think that is what you said, its natural
resonant
> frequency used as a grounded quad would be 296 khz. I expect there is
some sort of
> loading to resonate on 137 khz.
> It would be interesting to check whether it radiates better as a loop or
a long wire
> with the grounded far end disconnected. Judging by experiments in the
past using
> loops v verticlals, I think the vertical/long wire approach would be
better for low
> angle.
> I have tried a variety of loops in the past for 160 metres ie 40 m loop
resonated on
> 160 and although it was quieter than my full size quarter wave on 160, it
was not as
> sensitive and did not pull in the long haul low angle dx, in fact there
were signals
> that  I could not hear that I was able to copy solid on the vertical,
although at
> times probably noiser. Small loops for short/medium distances of several
hundred
> miles are acceptable but for low angle long haul poor on mf/hf.
> A full size loop ie quad or delta etc resonant at the operating frequency
and
> preferably at least a quarter wave above ground is a totally different
story.
> In the UK stations using loops have poor signals compared to those using
verticals,
> even low verticals heights with top loading. A couple of stations that
have been
> using loops have changed over to verticals and although not very high
made a hugh
> difference to their signals received at my qth.
> The so called long wire, just a few feet above ground and fed with a drop
wire is
> really a top loaded vertical or inv L.
> The above comments are a result of experiments and observations,
especially on 137
> khz and 1800 khz bands
> 73 de Mal/G3KEV
> Andre' Kesteloot wrote:
> 
> > Wooops,
> > I guess I did not express myself quite clearly enough.
> > The far end of the wire terminates in a field , (and specifically near
a pond)
> > visited by many cows.  In order to avoid any possible unpleasantness
(wire
> > falling on the ground if broken by the wind, etc.), we decided to
ground that
> > end.
> > It may well be that the whole thing operates as a loop of sorts, as
there is a
> > non-zero resistance between the two grounds (the one at the Tx site,
and the one
> > at the pond end)
> > 73
> > Andre'
> >
> > Dave wrote:
> >
> > > Surely the Voltage gradient is just the same but the other way round?
High
> > > current point at the earthed end and high Voltage point at the TX
site as it
> > > is about a quarter wave....
> > > The "earthed at the far end" idea has been used with topband antennas
for
> > > years in order to get the current into the vertical drop.
> > >
> > > 73 Dave G3YXM.
> 
>