To all intents and purposes a short (in wavelengths) vertical
attached to an arrangement of horizontal wires is a simple
(capacitively) loaded vertical.
The horizontal part will radiate, especially if it has a vertical
component rising higher than the feedpoint, but most of that
radiation will be cancelled by its reflection in the ground.
Several unbelievers have tried using purely horizontal transmitting
antennas and have had poor results. The beauty of amateur radio is
that you can prove something to yourself, but it won't change the
laws of physics.
Of course, every electrically small Marconi that is not in free space
performs in a complex way, but the result of that complexity is small
compared to the predominent omnidirectional radiation from the
vertical section. There is very little difference between various
arrangements of capacity hat, so long as you follow the rule to put
up as much wire as possible, as high as possible and covering as much
ground as possible.
Mike, G3XDV
==========
> Not sure why you talk about wire separation,
>
> Verticals properly are quire simple, this is not a pure vertical
> and not very simple to evaluate , Your making the assumption,
> that the system stops radiating at the point of connection to
> the loop ? .
>
> The feed is at the corner making a Y and not a T .. hence the
> question ,
>
> At what point dose the transformation take place , radiator to
> loading ?
>
> G,
>
>
> From: Andy Talbot
> Sent: Wednesday, November 04, 2015 9:11 PM
> To: [email protected]
> Subject: Re: LF: Capacitive top hat question
>
>
> 16 US units of length ~ 4.9m, so that means it's a bit more than half
> the height of mine. The top hat is near-enough infinite to all
> intents and purposes, so its real height is 4.9m. My antenna is
> only 7m high, with much smaller top hat. That amount of top
> capacitance will drastically reduce the ground resistance, so all more
> than likely all quite an efficient vertical radiator. If there is
> enough buried metal in the ground it could be very good indeed. so
> we're probably talking about a similar performance - perhaps an
> efficiency of -40dB on 137kHz. That's what mines comes out as,
> anyway.
>
>
>
> Horizontal radiaitors don't when they are close to a reflector. And
> the same good ground system that makes it radiate vertically stops the
> horizontal bit doing anything. If the ground were very poor, sand
> for instance with littel wire underneath, then perhaps the horizontal
> part may generate some ExH, but then efficiency would no doubt be so
> poor that teh Hpol contribution would be insignificant.
>
>
> Not sure why you talk about wire separation, he said they are strapped
> so its just a two wire, fat vertical. Which is exactly what I use -
> two paralleled conductors of a twin feed.
>
>
> Vertical antennas really are quite straightforward to analyse /
> measure
>
>
> Andy G4JNT
>
>
>
>
>
>
> On 4 November 2015 at 20:21, Graham <[email protected]> wrote:
>
> I dont think its that simple Andy ,
>
> 16 ft is not much for 136 , and the loop runs up from the
> feed point , which I think is a corner ,, so at what point
> is it a radiating element and which point is it top loading
>
>
> Ae could look like a sloping Y at some point , the wire
> separation must be too much to act as one ?
>
> G,
>
>
>
>
> From: Andy Talbot
> Sent: Wednesday, November 04, 2015 8:00 PM
> To: [email protected]
> Subject: Re: LF: Capacitive top hat question
>
>
> A pretty thoroughly top loaded vertical, Heff = Hactual
>
>
> 'jnt
>
>
>
>
> On 4 November 2015 at 19:50, Graham <[email protected]> wrote:
>
> (about 16 fee thigh, strapped together at the base only)
>
> I wonder what exactly is radiating Chris ?
>
> what to you estimate the beam pattern to be , I have the
> idea , south to SV is down , compared to say North TF ? , the
> levels into Iceland are significant ..
>
> 73-Graham
>
>
>
> --------------------------------------------------
> From: "Chris Wilson" <[email protected]>
> Sent: Wednesday, November 04, 2015 4:29 PM
> To: <[email protected]>
> Subject: LF: Capacitive top hat question
>
>
> 04 November 2015
>
>
> On my 136khz set up I have a short piece of ladder line (about
> 16 feet high, strapped together at the base only) feeding the
> corner of my horizontal quad loop, which is about 460 feet in
> circumference. If I am TX'ing with WSPR I can walk around under
> all of the loop and a fluorescent tube at waist height will
> light quite brightly. Should the loop also radiate as well as
> the vertical section? Sorry for the probably naive question, I
> am not sure whether it's normal or not, thanks.
>
>
>
> --
>
>
> Best regards,
> Chris mailto:[email protected]
>
>
>
>
>
>
>
>
>
>
>
> -----
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>
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