[BC] Ground system

[Milton Holladay]

Push this idea a bit further:  put the skirt  halfway up the tower with 
all guys and the base  insulated and you've got a vertical dipole, 
center fed.
Visualize what you proposed as the dipole with a foreshortened bottom 
half augmented with radials to "top"load it, so to speak.  Grounding the 
base should give even more "top", actually, bottom, loading.

Now, does this way of looking at it enlighten or confuse ?
M

On 2/12/2012 17:33: VIRUS ALERT!, Craig Healy wrote:
> How about this?
>
> A tall tower, maybe 500' commonly used by 50kw FM stations.  To add an AM to
> it, use a skirt feed.  Rather than at ground level, put the feed up at the
> lowest guy wire point.  Bond those guy wires to the tower and put a long
> fiberglass insulator a quarter wave or slightly more out from the tower.
> Those become the radials.  Insulate all the above guy wires just as at any
> AM station.
>
> Yes, the ATU would be up on the tower, but it's no real issue.  If there has
> to be a base current reading, do it with a video camera remotely.
>
> No copper to be stolen, tower itself grounded and no need for an isolator
> for the FM or STL cables.
>
> The skirt feed length would depend on frequency.  If the AM was at the upper
> part of the band, the feed could be up another guy wire level or so.
>
> Craig Healy
> Providence, RI
>

-- 
Milton R. Holladay Jr. / miltron at att.net
Columbia, S. C. / 803-331-8059
RF Measurements / Planning&  Installation / Emergency Service&  Parts