[Antennas] Dumb question?

[AI4WM]

It is my understanding that a sharp object will attract a strike by
build up of static charge.  A fuzzy object like the static dissipation
systems used by some broadcasters and commercial communications people
(police & fire and such) will dissipate a static charge thus
preventing a strike.

I've seen static brushes and nets used at several TV stations where I
maintained some FM installations.  Here in FL FDOT uses them on their
com towers at the weigh stations.
 I forget who made and installed them but here is one from altec:

http://www.allteccorp.com/resources/brochures/TerraStat_Brochure.pdf

73,
Bill
AI4WM

On Sun, May 17, 2009 at 4:00 PM,  <bonddaleena at aol.com> wrote:
> Hi, here is a question I would like to put before the list....
>
> I have just finished getting my 2 - 95 foot towers up. They are well
> engineered and guyed VERY well with 1/4" EHS guy wire.
> The towers are well grounded with low imped copper strap from each leg
> to a system of 8' ground rods all interconnected.
> I have had tall towers like this at my last 4 QTHs and never had a
> problem with lightning DIRECTLY hitting a tower. I have had some 'near
> misses' which have taken out several mast mounted VHF and UHF GaaSFET
> preamps , until I learned how to protect them.
>
> However, I was watching a special last night on Ben Franklin and they
> went into great detail about how he invented the 'lightning rod'
> concept.
> I have read extensively about this subject, but still have this
> question on my shrinking mind:
>
> Since I leave near the thunderstorm capitol of the USA (Florida), would
> I gain any safety by installing a very pointed conductor at the very
> top of my tower's mast?
>
> One tower will have a pair of 432 MHz long yagis at 115'. They will be
> fed with 7/8" CATV hardline and have the preamp near the rotor.
> I have ground straps to bypass the rotor. The antennas are all at DC
> ground, so there would be a direct path to ground for everything on the
> tower.
>
> My feeling is that by placing a sharply pointed 'tip' to the top of the
> mast will help dissipate a charge before it builds to strike potential.
> As you are aware, this is how Ben's stuff works. Lightning rods cannot
> withstand a direct 'hit'. They are for dissipation purposes.
>
> OR, am I inviting a strike with the pointy rod????
>
> I've not seen this topic discussed before.
>
> Thank you in advance.
>
> ron
> N4UE
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-- 
73,
Bill
AI4WM