Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!husc6!think!ames!ucbcad!ucbvax!cbosgd!cwruecmp!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: sci.electronics
Subject: Re: Lightning Rod Problem
Message-ID: <616@neoucom.UUCP>
Date: Sat, 4-Jul-87 14:08:30 EDT
Article-I.D.: neoucom.616
Posted: Sat Jul  4 14:08:30 1987
Date-Received: Sun, 5-Jul-87 07:38:44 EDT
References: <204600003@prism>
Organization: Northeastern Ohio Universities College of Medicine
Lines: 31
Summary: Radio design manuals advocate use of sphere on tip


Several books I have on antenna design recommend using a small
metal or even plastic ball on the tip of whip or pole type
antennas.  The two books I looked at don't show mathmatical proof,
but claim that the increased surface area of the ball makes it
easier for static to dissipate.

The claimed result is that generation of small sparks is reduced,
thus cutting down on the amount of crackle emitted from the speaker
of a receive attached to said antenna.  Supossedly, this is
especially helpful on car radio antennas.

I once had a car where to little ball on the tip fell off during
the time I owned the car.  I didn't notice any difference in the
performance of the radio after the tip fell off.

Since the purpose of a lightning rod is to dissipate static that
could attract a lightning bolt.  It seems that the increased
surface area of a ball-tipped lightning rod would be helpful.

Does anyone out there have any information on dealing with
lightning strikes in *very* tall buildings.  On a building several
hundred feet tall, lightning hits would essentially be assured.

I've seen some commercail radio transmitters with quite ealborate
spark bussbars and gas filled tubes, etc.  I've never had the
chance to take to the engineer at such a facility about lightning,
but I'd imagine that radio and TV towers are also routinely hit.

--Bill
(wtm@neoucom.UUCP)