Keeping lightning off antennas

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Jason Hsu:
Is there a way to prevent or reduce the risk of lightning striking antennas?  I am aware that any good outdoor antenna should be grounded to a buried 8-foot ground rod.  The idea is to route the energy from lightning strikes directly into the ground, which allows it to bypass the radio equipment and thus avoid destroying it.

However, I still don't want lightning to strike so close by.  In addition to the property damage, I would imagine that a lightning strike so close by could damage one's ears from the EXTREMELY LOUD explosion.

The only solution I can think of is to take down high outdoor antennas before a thunderstorm (or when going away) and to use an indoor antenna instead.

Philip Camera:
Do a search here on eHam for Lightning or for Grounding and you'll get tons of info on this subject.  Also, indoor antennas can have energy induced onto them just as easily as outdoot antennas.  

Finally, if someone knows of a way to keep lightning from getting close to one's QTH, contact me.  We'll be very rich!  Phil  KB9CRY

Alan Applegate:
You should also visit the Polyphaser site too.

Contrary to popular belief, there is no way to keep from getting hit by lightening. Lightening rods, like well grounded towers, do help bleed off the charge thus reducing the likelihood of a strike. They even offer a cone of effective protection for adjacent structures. However, if you get a direct hit, nothing, repeat NOTHING, will save you. The amount of damage might be mediated, but that's about it. It is, after all, hard to control several million volts at thousands of amperes.

Alan, KØGB

Michael S. Higgins:
You can not avoid lightning by taking an antenna down. When you QTH is in the cone of incidence (about 15degrees from the cloud base), the lightning leaders will form from the ground or any ground path including you house wiring, phone cable, TV cable or metal work and a strike can develop. The best solution is to minimize the damage to your structure and station by employing proper surge protection.

My property and antennas get struck by lightning about two times a year on average in Colorado. From June to September we have lightning storms every day. On average, the front range of Colorado will receive about 40,000 ground strikes every day. I can attest with proper surge protection and technique application you can mitigate surge damage.

The surge strike will travel many thousands of feet in the total distance your antenna and tower is a tiny percentage of that distance. I have seen lightning hit a tree and miss a 400 foot tower 100 feet away.  Disconnecting coax may make some hams feel good but the strike will just travel from the disconnected coax to the nearest ground. If you radios are near a ground they will become part of the path coax or not.

It is best to install proper surge protection on you home and station. As others have stated, go the PolyPhaser site and do some reading.

The quick answers others wrote might lend some to believe nothing can be done. But of course there are things you can do. There just aren't any "guarantees" that lightning won't strike your antenna, tower OR simply induce enough energy into your cables "by the presence" of such power, as to cause damage to your equipment or home even.

IF you put antennas on towers, including hanging your dipoles or vee or loops from them, this is probably a better situation for your protection. You can add one or two "Static Discharge dissipators" to the top and near-top of your tower, which will help dissipate a build-up of energy, which seems to lessen the chance of direct hits. They dont cost much, the theory seems sound, and there is a history of proof developed that these work. These need to have a good ground cable or strap all the way down the tower, tied to the tower periodically and connected to a multi-ground rod system at the base.

The next thing I would like to do (just talking, havent done it yet myself!), is create a "grounded entry panel" for EVERY incoming cable, coax, rotor, etc. On every panel you would have numerous coaxial double-female "bulkhead connectors" mounted. Each coax from an antenna outside is screwed onto one of these. Inside the house wall, a shorter "coaxial jumper" cable will connect to your radio (tuner, amp, whatever is first inside). My thoughts might also include standing this plate off the outside wall of your home by a thin thermal block (drywall material 3/4" thick?) which would prevent heat and energy from going directly to the outside wall materials.

As a more complete precaution to the "entry plate" idea, add coaxial lightning protectors to this panel, so each coax signal passes thru a well-grounded lightning suppressor.

But I would think just having the well-grounded entry plate will do a lot for you, AS LONG AS YOU Disconnect every "coax jumper" cable inside, when you are not operating a radio. This puts your radio up to several feet from the incoming cable which terminates outside the wall on your well-grounded entry plate.

If you use AC power supplies to power your radios, high grade AC line surge protectors are also a good idea, again well grounded and tied into your electrical ground system, and all PS's should be connected to this AC line protector. Rotator line  protectors are also available.

This is a BIG subject and you could get wrapped up heavily in trying to do all the things it might take to seemingly "do it right".

At least this is a good start.

By the way, a company named POLYPHASER offers all sorts of lightning & EMP protectors, and their Catalog is amongst the BEST at explaining the things that can be done. Well worth reading.


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