Re: LF: Finbar's Compact 500kHz Vertical

[Rik Strobbe <rik.strobbe@fys.kuleuven.be>]

Dear HaJo,

> But in general I feel that
> antenna height should not be disregarded. Even with equal ERP sky waves
> may develop better from higher aerials.
>
> HW?

I guess that the only cause that 2 antennas fed with the same ERP produce
different signals is a difference in the (vertical) radiation pattern,
ie. the takeoff angle.
I simulated a 30m, 10m and 3m vertical (at 502kHz) with mmana_gal and
found only very small differences: from 18.2 degrees for the 30m vertical
to 18.6 degrees for the 3m vertical. This for a uniform ground with a
conductivity of 10mS/m.
Making the ground poor (1mS/m) results in a takeoff angle of about 26
degrees (+/- a few tenths depending on the height).
Increasing the conductivity to 100mS/m reduces the takeoff angle to 12-13
degrees.

73, Rik  ON7YD - OR7T

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