Antenna Grounding

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Fielder3

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Question regarding ground... I live in an area that has very LITTLE lightning activity. Does grounding a outside base antenna help reception, or does it even matter in that regards?

( I have a 2-meter omni directional straight stick 5' roof mount antenna and use LMR400 cable) I listen to US Forest Service, BLM and state forestry on VHF and going for "distance." There are a few base stations 100-120 miles away that I'm picking up off/on.

Thanks for feedback.
 

popnokick

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Grounding really has little to do with lightning in the event of a strike. May minimize destruction to just melting/fusing your electrical system, antenna, mast, connected radio(s) and small fire(s). Grounding can be immensely helpful in diverting the energy from a nearby strike... If you have proper arrestors and grounding. Oh yeah... RF ground (different from electrical ground) does help antenna functions, and helps keep RF from getting into places you don't want it.
 

WA0CBW

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Grounding your antenna (i.e the mast supporting the antenna) is required by the NEC (national electrical code) and includes grounding the coax shield to ground before it enters your house. The NEC also requires all external ground rods to be connected to the building electrical ground. The purpose of this is to help equalize the charges between the ground and the sky and reduces the chance of a lightning strike. Just like lightning rods the purpose is to equalize charges not attract them. This is why most commercial radio antennas are "DC grounded" meaning there is a direct short between the radiating element and the ground plane of the antenna. In most installations grounding your antenna won't noticeably improve your reception. If it does then there are other "grounding" issues that need to be addressed.
 

ko6jw_2

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I think WA0CBW's response addresses the grounding issues very well. I just wanted to suggest that you re-think the antenna itself. USFS and BLM frequencies tend to be in the 164-174Mhz range. This is quite far outside the 2 meter antennas bandwidth. Although the antenna is clearly designed for some gain on 2 meters, you may actually have negative gain 20-30Mhz outside its intended bandwidth. The higher the gain of an antenna, the narrower the band width. I have separate base and mobile scanning antennas which are designed for that purpose. My experience with the local USFS frequency of 170.550Mhz is that 2 meter gain type antennas do a very poor job. You might do better with a discone or, if the stations of interest are in one direction, a yagi tuned for the desired band.
 

jim202

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Grounding really has little to do with lightning in the event of a strike. May minimize destruction to just melting/fusing your electrical system, antenna, mast, connected radio(s) and small fire(s). Grounding can be immensely helpful in diverting the energy from a nearby strike... If you have proper arrestors and grounding. Oh yeah... RF ground (different from electrical ground) does help antenna functions, and helps keep RF from getting into places you don't want it.
I can tell that your listening to old wife's tales about grounding and lightning. If your side of the story was true, all the cellular carriers would be replacing towers and antennas after every storm that went through. All the off the air TV stations and FM broadcast stations would be in the same boat. These towers take hits all the time. Most of the time the tower takes the hit, the grounding and surge protection does it's job and the equipment keeps right on trucking. I have seen towers take a hit, stand there steaming in the rain from the steel getting hot from the high current passage. Went inside the equipment shelter and everything was just playing the way it should.

As has already been mentioned, the NEC does have a section on grounding of telecommunication facilities and TV antennas on homes. It would be good advice to follow what they have to say.

Another good source is your home owner's insurance company. They normally have some guidelines that should be followed. If you don't follow their guidelines, they could refuse to pay on any damage that may take place to the dwelling or contents from a lightning strike.

Another piece of advice that I will pass along is if you have an old house, it would be a good idea to replace the ground rod at the electrical meter. These ground rods don't last forever. They tend to oxidize with time and loose their low resistance that your looking for. If the house is over say 10 to 15 years old, I would change out the existing ground rod.
 

doublescan

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Jim202 that sounds like good advice, I have an old house and just happen to have a spare ground rod made of real copper. Would the wire going to the breaker box need to be replaced also?
 

popnokick

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Major difference in commercial grounding installations vs. residential in what they are designed to protect and cost. It will be interesting to see how many replies to this thread report sustaining residential lightning damage... Even if NEC grounding was in place. Perhaps what I've seen is unique, and lightning damage really is mythology....
 
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