Re: Longest practical ground cable?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

ALthough a better antenna than the secondary, it's still a darn bad
antenna... at 300 kHz, wavelength is 1000 meters.  A 10 meter wire is 0.01
wavelength long.  It's a lumped component, if anything.


Tesla list wrote:
> 
> Original poster: "Malcolm Watts by way of Terry Fritz
<twftesla-at-uswest-dot-net>" <m.j.watts-at-massey.ac.nz>
> 
> On 2 May 01, at 18:00, Tesla list wrote:
> 
> > Original poster: "Garry Freemyer by way of Terry Fritz
> > <twftesla-at-uswest-dot-net>" <garry-at-ndfc-dot-com>
> >
> > What's the longest RF ground cable I can have?
> >
> > I've been thinking maybe I could drive a rod on the edge of my porch.
> > Trouble is, the thing is 30' away. That seems to be too long. With ham
> > radio, if I remember correctly, the ideal ground cable has to be
> > shorter than a quarter wave of the frequency you are transmitting on
> > or it could act as an antenna.
> 
> It *will* act as an antenna and if it's longer than the TC secondary
> it will radiate more effectively than the secondary itself although
> the effect can be killed to some extent by running it along the
> ground. In effect, the ground will will behave as a horizontal
> radiating element with the secondary acting as a capacitive top hat.
> 
> Anyone else?
> 
> Malcolm