[BC] Long Wire

[Steve Lewis]

A couple of questions, Phil...

Please explain a "girdle" you recommend for the top and bottom of this
configuration - I'm assuming it is something more than simply a ring that
connects the drape wires.

And the bottoms of the drape wires are connected together in some sort of
spider arrangement where all drape wires are fed with equal length jumpers
and no ring, correct?  Is that true of the top as well?

And if I understand you completely, the vertical wires are always to be 90
degrees.  In the case of a 90 degree tower, the feed point would be near the
ground or at least the top of the pier?

If this arrangement were perfect, what would you expect the impedance of the
skirt to be?

-----O'rig Msg-----

 From: Phil Alexander

It was Ron Rackley who pointed me in the right direction for
making skirts perform and when I started doing modeling,
surprise, surprise the model showed his ideas hit the nail
squarely on the head, namely: minimum 5 foot clearance; top
attachment at **90** degrees; use an ATU to match the skirt
to coax - never try to do it with jumpers between skirt and
tower.

Some other things I've found while modeling: use girdles at
top and bottom; use a balanced drive spider at the bottom;
use top lightning rods extending above the attach/support
point equal in length to the height of the bottom girdle thus
making the extended drapes exactly 90 deg total height, 
attached exactly 90 deg above the base of the steel.

In the model this configuration always yields < 0.5 dB loss
(usually quite a bit less) as compared with the same tower
driven with a series fed base and base insulator.