Eznec is your friend Dave. Having used a previously short Vertical 51ft for
20+ years, the top loading is not your problem. Because the feed Z is low you
will require longer radials. Mine are typically 0.4 wavelengths.
I will stand corrected but the formula is E (efficiency) = Feed Z/ Feed Z plus
loss (the loss being mainly ground loss)
So typically with a short vertical we could have 12/ 12+ plus loss which could
be any amount dependent on your radial system.
The only way to deal with this is either by a vast radial system or a taller
vertical. In the end it's all a numbers game.
73 Clive GM3POI (306 current confirmed)
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of David Cole
via Topband
Sent: 13 June 2017 21:08
To: topband@contesting.com
Subject: Topband: Short Verticals
Hi all -
Assuming a standard 1/4 wave vertical is 36 ohms - is there any formula that
will calculate the Z if the vertical is short and brought to resonance by top
loading wires - I understand the Z will be less - but how much by ? I am trying
to use the formula on ON4UN disc to calculate the approx LC ratios for a
Lahlum-Lewallen phasing system.
Thanks Dave g3rcq
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