Thinking of adding an LNA but read that it’s much better if the whole thing is grounded.
For just an antenna how long of a grounding rod do I need? I see 8 feet but that seems a bit long for just an antenna.
Additional, I know I need to ground it between the antenna and the LNA. So I just solder a ground wire to the antenna connector? (I have the flight aware N female antenna)
hmmm … at microwave frequencies, grounding is usually for lightning protection.
Do you live in a lightning prone area?
No. I guess the worry is static discharge over an LNA causing it to fry the LNA.
We do get lighting but the antenna will be far lower than anything else around it (trees, houses) and close to both.
Maybe I’m over worrying here.
Suspect so!
Nothing will survive a direct hit.
If you do want protection, a Gas Discharge Tube (GDT) is a good way of doing it
https://www.rfi.com.au/comms-products/rf-components/lightning-protection
I have added a gas discharge tube, on the coax cable, in the house.
Outside I have pounded in a 4 ft rod, and connected the metallic part of the antenna with a long #12 copper wire.
I was thinking if I do ground it I’ll use one of those pipe clamps that people use to ground into water pipes. Is that what you used?
Yes. It’s just sticking a bit above ground.
The thickness of your grounding will also matter. I have a 6ft rod that’s about only a half inch in dia. It is also tied into my building code via the plumbing ground per NEC requirements.
The NEC (NFPA 70) sizes ground rods for power ground fault, not for lightning strikes or static electricity.
NFPA 780 deals with lightning protection.
Mine is 1/2" diameter. I feel it is sufficient for static.
Many people misunderstand the purpose of grounding an antenna mast. It’s not to protect you against a direct lightning strike. Not much will do that. It’s to bleed off the static electric charge to ground before it builds up enough to result in a lightning strike.
What I was reading about was that buildup of static electricity can fry the LNA since the components are cheap /sensitive. Grounding would be more for that.
Seems confusion over electrical ground and lightning protex. Not the same.
I ground my ham gear so that my driven element has a good reference. The same theory works for the Ghz spectrum.
Grounding is good!
I got a 4 foot grounding stake and ran copper wire from it to the antenna so at least now it’s grounded for static electricity buildup.
Test it with a volt meter - no point generating your own earth loop.
I had a direct hit to the house last summer. I have a whole house surge suppressor in the panel (for what it’s worth), but that was essentially bypassed since it nailed the garage peak. Surge ran down the metal trim, blasted thru the shingles and wood (the front of the garage is the style that there is maybe a 18" overhang right above the garage doors) to the metal soffit, then proceeded to follow the soffit around the house. The outdoor metal can lights that point down are grounded, and you could see where the surged jumped from the trim to the grounded can at almost all the lights. RIP LED outdoor lights.
Anyways, all kinds of stuff got wiped out. Saw some arcing marks on the FA antenna mount (that was grounded), the orange FA power supply lit up like a sparkler (no surge protector on it - fail). As it traveled around the garage soffit, it got into the internet connection and took out the internet box and my router. I have a TV antenna in the garage attic, no issues there. GFI plugs didn’t fair too well, same with some Z-wave wall switches
The weakest links? By a mile…HDMI ports. 2nd up is the network ports. Amazon Fire Stick streamers - the power supplies got nailed too.
Interestingly, the various cheap network switches scattered around the house actually did a good job of inadvertently acting as a ‘fuse’, preventing more damage down the line. The switches internal protection diodes seemed to stop the surge in it’s tracks, but at the cost of wiping out the switch.
Since then, I’ve beefed up the grounding on the new FA antenna, added a gas discharge tube arrestor, and added a quality surge protector at the orange FA power supply. Added a few ethernet suppressors for the longer Cat6 runs and where the ethernet comes into the house.
One thing that did catch me off guard is the vastly different clamping voltage specs on the surge protectors. Some are 300-400V, others were 900V. 900V? - why even bother! Probably like most, I tended to focus on the joule rating (wrong) - that’s only half the story.
Rather interesting playing detective, trying to figure out all the paths the surge took.
No kidding…more than once I thought about that afterwards. I’m a RF engineer (transmitters), and the wife said mother nature was getting back at me for all the RF I caused to be radiated over the decades. LOL
Interesting sidebar: I was worried about potential damage to wiring behind the walls. Without ripping out a BUNCH of drywall, how would I know it was OK? I even kept beakers that had tripped off until an electrician came out. And I knew darn well the insurance company didn’t want to pay for something that might not be damaged. And honestly, I didn’t want the house torn up anyway - but I still worried about it.
The solution? I had the electrician install Arc Fault Breakers in the breaker box on the lines I thought might have been candidates for damage. Thought was, the breakers would spot an issue and trip before any fire hazard. I thought that was a good comprise and the insurance even paid for it.
That’s a good upgrade, the AFCIs. It’s required in all the new houses.
The panel surge arrester is good only for surges from transformer to your house. And, like you saw, you get what you pay for.
Most of the suppressors are made to stop power surges, slower in rise time than the lightning surges.
All my electronics are plugged in extension cords with surge suppression on them or in UPS with internal surge suppression.
Yeah a direct hit is going to do some damage because there is no lightning arrestors and grounding for it on residential buildings. So it will follow path of least impedance.
Being a step impulse, every bend will be seen as an impedance, so it will build up transient voltage on it. For example, a 90 degree bend in the “grounding wire” will act like a blocking impedance for the lightning step pulse.
Different voltage ratings are probably different just because of the pulse shape they are reported to.
Slower pulses will be clamped at lower voltages than faster rising pulses.
Exactly