Antenna Safety Question
 

I got a YAGI antenna and put it in my attic -- helped me get rid of FM
static problem I had been experiencing with just the basic dipole antenna I
was using.

But I was wondering ...
is there any issues with lightning like if the antenna was outside or is the
fact that the antenna is in the attic and covered completely by roof make
that a non-issue

Thanks for any info (p.s. I know some people are probably laughing at this
as a dumb question -- but I figure better to ask then take a chance on
toasting my house!)

Thank you

mBird,
The likelihood of your antenna in the attic being hit by
lightning is about the same as winning the lottery. Not
impossible, but don't hold your breath.
'Doc

Treat it like an outside antenna.

Wise words, up to a point.

1) Hardly any difference in the face of a near hit. EMP will hit the
antenna through non-conducing roof.

2) No problem with static accumulation, though. That is due to the
direct interaction of wind / rain / snow and outside metal.

3) Also, IMO, reduced risk of direct hit. Old fashioned lighting rods
featured tall spikes to provide a preferental path to ground for a
lightning. Today's standard solution is a set of flat conductors that
still provide a preferential path, but do not stand up "inviting"
bolts, thus reducing somewhat the likelihood of a hit. (They also
affort little or no protection to nearby property, unlike the older
design).

This in not so clear cut though.

If grounded, an attic antenna will become statically loaded anyway as
the bolt potential builds up. The point effect will be there, leading
to a potential dielectric-perforation risk. The roof will indeed
afford additional isolation, depending on how much material (roof +
DRY air) is between the antenna and the moist outside air in an
electrical storm _with_ rain. I don't know the exact figures, but I
think rainstorm bolts are more common that dry air bolts.

Take your precautions!

Filippo

Must agree, as , in my youth, had neighabor liveing across the street, in
Portland, OR., this on the valley floor, had her Electric Range struck by
lightning, tho, must also agree with Doc, the odds are not much better (or
worse, depending on your outlook!) of hitting the lottery. and, if your
home is serviced by power lines on poles, there is USUALLY a GROUND WIRE ,
at the top of the pole line, and, as lightning USUALLY takes
the path of least resistance, would be the object struck by lightning. It
never hurts, tho to provide lightning protection, just for
general safty. Jim NN7K




"CW" wrote in message
news:aMDpb.72275$mZ5.450665@attbi_s54...
Not at all a dumb question. There are many people that think if it's
inside
you don't have anything to worry about (the ostrich syndrome). Lightning
doesn't care much about your roof nor does static. Treat it like an
outside
antenna.
"mBird" wrote in message

Jim wrote:

... must also agree with Doc, the odds are not
much better (or worse, depending on your outlook!) of hitting the
lottery. ...

Actually, I read somewhere that you're about 1000 times more likely to be
hit my lightning than to win the PowerBall. I would imagine it would vary
considerably depending on which state lottery you're comparing it to, but
I'd also imagine that lottery odds are in general much longer than being
hit by lightning odds (i.e. winning the lottery is much less likely).

On Wed, 05 Nov 2003 02:22:29 GMT, asdf wrote:

Jim wrote:

... must also agree with Doc, the odds are not
much better (or worse, depending on your outlook!) of hitting the
lottery. ...

Actually, I read somewhere that you're about 1000 times more likely to be
hit my lightning than to win the PowerBall. I would imagine it would vary
considerably depending on which state lottery you're comparing it to, but
I'd also imagine that lottery odds are in general much longer than being
hit by lightning odds (i.e. winning the lottery is much less likely).

Guess I'm gonna have to ask for better odds as my tower gets hit bout
3 times a year on average.
http://www.rogerhalstead.com/tower.htm
There are taller towers around, but it's two miles to the nearest one.

Considering I never disconnect the gear I've had very little damage.
One direct hit really frazzled the end of the big 144/440 vertical,
blew off all the coax seal and tape, and even removed the plating from
all the connectors at the top of the tower. I did lose the front end
out of the 2-meter rig on that one. The water running out of the 9913
after the lightening removed the coax seal was at least as big a
problem.

One-of-these-days I'm going to get some static balls up there to see
if they make a difference.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)