LF: Antenna height and length

[André Kesteloot]

Peter Bobek wrote:

> Gentlemen,
>
> I have been following the recent discussions about effective antenna height
> / toploading of
> rather short aerials... (Note: SHORT aerials)
>
> May I point out that there has been a good article published in
> "ELECTRONICS & WIRELESS
> WORLD" (April 1985 issue) which deals with basic fundamentals.
> (there are some printing errors, however...)
>
> Two sentences in this article are worth to be mentioned here:
>
> 1.)  For Rr = 1 ohm (radiation resistance), aerial height (without top
> loading) has to be about
> 18 electrical degrees.
>
> (.....this is pretty close to a height of 110m at 136.5 kHz!)
>
> 2.)  Optimum top loading doubles the effective height and quadruples
> radiation resistance.
>
> (....you can´t expect more!)
>
> The higher the vertical portion of your LF antenna the less likely it is
> that you will actually quadruple
> its radiation resistance - even with perfect top loading!
>
> Regards,
>
> Peter/DJ8WL (DA0LF on LF)