TopBand: verticals

[Peter Chadwick]

>This is a long-held fallacy--that the higher impedance of the folded
>unipole reduces the ground losses.  The impedance transformation
>of the folded unipole also transforms the ground loss part of the
>equation in the same way and there is no net improvement

Interesting. The 'Services Textbook of Antennas and Propagation' by
Glazier and Lamont defines radiation resistance as 'the resistive
component of the input impedance of an aerial [antenna]'. On this basis,
the radiation resistance must go up when the impedance goes up. But if
the ground losses are not very low, why couldn't I measure any change in
input impedance when adding radials - which you'd expect with alow
radiation resistance? And why can't I measure any current in them? 

Amongst professional antenna designers, I can find about a 50-50 split
between those who hold that the radiation resistance goes up, and those
that hold that it doesn't!!

I always felt that I never could understand radio - how I've made a
living at it for over 30 years I don't know!

73

Peter G3RZP

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