[TowerTalk] Verticals with Elevated Radials

[L. B. Cebik]

>,  kept my enthusiasm down (ok,  I am lazy)  from going out and
> hanging up a bunch more elevated radials!

Use care in interpreting modeling results relative to the real world.  It
is easy (too easy?) in a model to make a perfectly balanced n-wire radial
system and quite another to make one in the field.  A small imbalance
(<5% length difference) in one wire of the modeled radial system with 4
wires makes a considerable difference in the pattern shape.  This is
something that Dick Weber and others have been working on with finding a
higher Z point for starting the radials, etc.  With more radials, changing
the length of one by that same 5% makes far less difference.  Examining
the current tables of a given model will show the reason why.

So even if more radials than 4-8 were to reduce gain by the NEC-4
indicated amount of well under 0.1 dB, they may have other functions of
equal or greater importance.  With elevated radials, one may not need the
full 120 recommended for underground use, but more than 4 can relieve some
imbalance problems if one does not have the engineering wherewithal to
make a perfectly symmetrical system or cannot adopt one of the alternative
strategies in recent literature.  On the other hand, pattern shape
imbalance is not always a problem, since being a problem or good fortune
depends on where the bulges and nulls happen to fall.

This note is not intended to compare elevated and underground
radial systems, which is a separate subject.

-73-

LB, W4RNL


L. B. Cebik, W4RNL         /\  /\     *   /  /    /    (Off)(423) 974-7215
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                URL:  http://web.utk.edu/~cebik/radio.html



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