[Towertalk] More on Lightning protection

[Tom Rauch]

> May I suggest this company as an alternative way of thinking regarding
> lightning protection The last thing anyone wants is to make yourself a
> target. This company has a different approach... their system 'bleeds
> off' static electricity lowering the potential for a hit. The system
> works very well on sail boats (tall aluminum masts in the middle of
> the ocean tend to be a major attraction!) A friend and ham used to be
> the national sales manager for them.
> 
> http://www.lightningmaster.com/

The only known way to reduce the probability of a lightning hit by 
"bleeding off" charge is by sending a streamer of ions up to the 
cloud...since it is the cloud that actually has the concentrated 
charge.

(It's sort of like walking across the carpet shuffling your feet, and 
expecting that a "special device" on the door knob will prevent you 
from getting a poke.)

The problem is when the streamer gets near the cloud, a giant 
crackling flash occurs as several massive discharges balance the 
potential of the cloud to earth, which has a tremendous reserve of 
charge available.

There are some little whiskers that work very well on airplanes, and 
help prevent the airplanes from building up charges. But this is much 
different than trying to discharge the earth....which has 
considerable more electrical mass than a jumbo jet.

You can reduce the probability of a hit by making an object "blunt", 
so the voltage gradient is reduced (no sharp points). There is some 
possibility that the whiskers do this on a pointed object, because 
they can create an ion cloud around the attachment point of the 
whiskers.

It is very unlikely they would help a tower with a yagi even the 
smallest amount.73, Tom W8JI
W8JI@contesting.com