[TowerTalk] Dayton Antenna Forum (contd.)

[Jim Reid]

The comment was made:
 
> ON4UN mentioned in the beginning of his talk about the 
> K5UI's use of <1/4 wave length elevated radials to get 
> equal currents in the radials. 

Per my understanding,  getting equal currents is about a
2nd or 3rd order effect in this case!  The first order effect
of the low,  and now short radials,  is that very high voltages
will exist on these wires,  especially at the ends.  Therefore,
E field lines will easily reach the ground and induce much
of your rigs output power's current to flow in the ground 
resistance in an attempt to return to the antenna feedpoint.
And,  that is where the 3 to 6 dB of RF loss,  and loss of
radiated power occurs.

That is why the loss is much less over a great ground screen,
or at the beach;  the resistance to RF current flow is much
less than in our usual dirt in the backyard or out in the pasture.

That is also a benefit of elevating the base of your vertical, as
ON4UN did,  but he still had them over the ground screen,  he
just wanted the high current,  and therefore area of most
intense radiation up higher in the sky,  so he raised the feed
point.

73,  Jim,  KH7M


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