[Towertalk] Lighting Protection and Roof Towers

[Jon Ogden]

on 12/12/02 3:58 AM, Mark Beckwith at mark@concertart.com wrote:

>> if you
>> can make your antenna/tower look as much like ground as possible and
> prevent
>> any charge from building up on it, you are less likely to take a strike.
> 
> Does this mean that the side of a high dipole which is connected to the
> center conductor is a target?

UGH!

Any object in the air is a potential target.  Both sides of your dipole are.
While the side of the dipole which is connected to ground is at or near, RF
Ground, there is still a rather inductive path through your coax, etc. to
that ground point.  It does not look like earth ground.

One purpose of lightning protection is to prevent charge from building up
and hence contributing to a strike.  If you keep that from happening you
minimize your chances of a strike.  The best way to do that is with a good,
low inductance grounding system that will help prevent it.

You want to keep the voltage potential between the top of your tower and the
earth to be a minimal as possible.  Sometimes, it doesn't matter how good
your grounding system is and you will still take a strike.  But you lessen
your chances which is half the battle.

73,

Jon
NA9D

-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d

"A life lived in fear is a life half lived."