[Lf] Top Loading Vs. Base Loading]

[Andre' Kesteloot]

Richard Brunner wrote:

> This is somewhat apocryphal (doubtful authenticity), but, years ago, when
> working with Vince Pinto in up-state New York  from Massachusetts, I was
> using a fifty foot vertical.  When I added top loading, consisting of six 30
> foot wires at about 50°, he said I went up about 10 dB.  How 'bout that!
> With no top-loading, the effective height is 50% of the antenna height.
> With top-loading, effective height is perhaps 80% of the antenna height.
>
> Top loading coils, in my experience, act more like rf chokes - a bad idea.
> You want to get as much rf current as high as possible, and retarding it
> with a coil is counterproductive.  Think capacitance. (top-loading)
>
> Richard Brunner, AA1P, rbrunner at gis.net
>
> ----- Original Message -----
> From: <les at highnoonfilm.com>
> To: <lowfer at qth.net>
> Sent: Saturday, August 26, 2000 07:22 PM
> Subject: [Lowfer] Top Loading Vs. Base Loading
>
> >
> >
> > I know that in theory top loading our very short verticals would
> > improve radiation resistance. But I wonder if anyone has
> > ever compared just how much of a difference this would
> > account for.
> >
> > I have seen an NDB antenna system developed by Nautel called
> > the "Polestar" that used a tophat and top loading coil along with
> > a small variometer at the base for fine tuning. They claim
> > some pretty impressive benefits over a conventional base loaded
> > vertical.
> >
> > Has anyone ever done research into how much of a benefit
> > a typical lowfer installation could expect?
> >
> > Les Rayburn, N1LF
> >
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>
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