I'm trying to decide on placement of a new COM antenna and my prime spot is about 3-4 feet away from the magnetometer. Best I can tell RF shouldn't really impact the magnetometer, but it just feels wrong.
Will a COMM antenna interfere with a magnetometer?
- Thread starter Salty
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Check the magnetometer install instructions. I think its 3 feet for some installs, however, I seem to recall farther for other installs??
Good thought. It didn’t help though as it is installed and the com isn’t. It would be difficult to test prior to installation of the com antenna.
Half Fast
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Can you go beyond 5’? That would seem to make it a non-concern.
lol I’d never have thought of that myself.
The magnetometer is circled in blue. Top antenna is elt. Com1 is below the star. Next best place is under the inboard part of the gull wing where the red slash is. The adsb-in antenna is a few feet from there, but I don’t think that will be an issue.
I wanted to put the com2 where the gps antenna is now just above the star. Gps antenna would go under the canopy between the seats. The rear canopy slides back to the point of the star when open, so that area is not available.
I wanted to put the com2 where the gps antenna is now just above the star. Gps antenna would go under the canopy between the seats. The rear canopy slides back to the point of the star when open, so that area is not available.
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I think I’d try to keep the GPS antenna on top. Putting the comm antenna under the wing should put it plenty far enough from the magnetometer.
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All I can add is that my avionics guy has told me several stories about how tricky finding a right spot is - they are finicky. Got to be careful as well with LED lighting, cables, etc. He has to hunt a few times for the right spot before it gets sorted out.
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The magnetometer can only slew the DG at a relatively slow rate.
Your COM transmits for short periods of time and at infrequent intervals. As such, the net effect on a slaved heading system will be low, even if you have some interference.
I had an HF system affecting a magnetometer some years ago, a lot of interference (there was a slaving indicator in that system, it went full scale). Holding the HF keyed for a couple minutes at 200W of power barely moved the compass a degree. The same HF system managed to interfere with a FADEC, causing the engine to spool up uncommanded.
Stuff that is on all the time will have a more serious impact, but not a VHF COM.
Install that antenna in the spot you've identified, you'll be fine.
Your COM transmits for short periods of time and at infrequent intervals. As such, the net effect on a slaved heading system will be low, even if you have some interference.
I had an HF system affecting a magnetometer some years ago, a lot of interference (there was a slaving indicator in that system, it went full scale). Holding the HF keyed for a couple minutes at 200W of power barely moved the compass a degree. The same HF system managed to interfere with a FADEC, causing the engine to spool up uncommanded.
Stuff that is on all the time will have a more serious impact, but not a VHF COM.
Install that antenna in the spot you've identified, you'll be fine.
Gps would be on top, inside the canopy
This is pretty much my line of thinking.
Ed Haywood
Final Approach
My comm antenna and magnetometer are 3 to 4 feet apart and I have no issues. Both locations are the same as the American Champion factory uses.
The magnetometer is just inside the fuselage about where the bottom of the 4 is in my N number. Comm is on the roof.
The magnetometer is just inside the fuselage about where the bottom of the 4 is in my N number. Comm is on the roof.
What brand/system magnetometer is it?
Since its a metal airframe, you can rig up a temp ground plane for the #2 comm antenna and see if it messes with mag-meter? But looking at your intended location I dont see any issue based on my experiences. Worse case once you install it and find a problem you'll just need to move the antenna again.