[BC] Ground system

[Phil Alexander]

This was William Culpepper's original design. A few years ago while
I was in Charlotte for an AM Transmission Seminar and Radio Show
I had privilege of discussing this topic in detail with William. He
told me that 9 deg. was a first experimental approximation that 
worked so well he felt there was no point in trying other heights.
I believe this testing was done with 4 radials, but perhaps Milton
can settle that point because I believe he was there.

There are various theories about vertical profile of the wires, and
some sentiment supports a "gull wing" profile. The disadvantage of
this configuration is the high RF voltage inherent at the wire ends.
Keep in mind that economic efficiency is an equally important target
to radiation efficiency. IIRC, modeling I did shortly after my talk
with William seems to support the idea of using a conventional (i.e.,
3 ft. AGL) drive point with a 45 deg ground wire departure angle up
to a point 9 deg AGL extending 90 deg from the tower to an insulator
9 deg AGL. It can be seen that the near (tower end) support can be a
point between 2 insulators in a short guy cable while the far support
can be an insulator supported by a utility pole. 

Another point demonstrated by modeling is that galvanized guy cable
does not appear to reduce radiation efficiency unreasonably although
Cu jacketed steel wire (i.e., Copperweld) is somewhat superior, but
may not be economically justifiable especially when maintenance 
factors in some geographic areas (e.g., coastal) are considered. 

Phil Alexander, CSRE, AMD

-----Original Message-----
>From: Tom Spencer <Radiofreetom at gmail.com>
>
>I recall something about 9 degrees up needing no more than four 
>radials.