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Concrete runways with rebar interference

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Old 06-21-2002, 12:42 AM
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Hiflyer001
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Default Concrete runways with rebar interference

Anybody experience radio interference while flying off a concrete runway that has rebar of sort in it for strength?
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Old 06-21-2002, 02:13 AM
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Ed
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Default Re: Concrete runways with rebar interference

Originally posted by Hiflyer001
Anybody experience radio interference while flying off a concrete runway that has rebar of sort in it for strength?
Naaw. Just flew off acres of B-36 / B-52 reenforced concrete runways a few weeks ago. In fact hundreds of us did at the West Coast Festival without a hitch.

If anything, I would think that standing over such a grid would improve ones signal.

Jim
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Old 06-22-2002, 02:10 PM
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Default Concrete runways with rebar interference

I would like to find out if commercial runways with rebar could possibly be grounded since there is so much radio activity going on at the airports.
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Old 06-22-2002, 02:46 PM
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Default Concrete runways with rebar interference

Rebar in concrete is one of the best grounds you can have. Typically airports have extensive grounding. All the runway lights have a continuos grounding counterpoise run in the same trench as the cable, buildings have cointerpoise with ground rods every so often.

David Reid

P.S. I am an electrical contractor and do a lot of airport work.
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Old 06-22-2002, 10:36 PM
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Default Concrete runways with rebar interference

Our new runway is located in a gravel pit area which may not be the best grounding effect. You say everything is grounded. The question is why??? Lightening storms.....radio interference....Do we need to ground our runway....Our planes are getting knocked around too often. Any comments. We also have a lot of steel fencing in and around the pit area. We also are between two high power lines and about a half mile from cell phone towers??? Thanks for the comments.
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Old 08-31-2002, 06:41 AM
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Default Concrete runways with rebar interference

still having radio interference. any comments..thanks does steel fencing cause interference???
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Old 08-31-2002, 09:26 AM
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Default Concrete runways with rebar interference

I have flown off the runways at the Wright Patterson AF Museum. They are re-enforced and I had no problems.
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Old 08-31-2002, 12:49 PM
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Default Concrete runways with rebar interference

If you are having interference, I would suspect the cell towers. I do not believe that rebar and chain link are the cause. The power lines could also be a small factor but I would bet the bank on the cell towers. Good Luck Dave
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Old 08-31-2002, 02:49 PM
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Default Concrete runways with rebar interference

if you are having radio interference, I would look for an outside source of EMF emissions such as the powerlines and the cel towers. A passive rebar grid or chain link fence may absorb emf, I can't sse them being a source of EMF unless there is a substantial electric current passing through them. I have flown off full size runways, both military and civilian, and have had no problems....... I have flown near a cel tower and had problems. Our club lost 5 planes in two days immediately after a new tower was put into service a couple of miles from out field. We complained, and whatever they did, seems to have reduced the problem.......
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Old 08-31-2002, 03:27 PM
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Default Concrete runways with rebar interference

I would rule out Cell Towers, they are way too high in frequency to interfere with either the 72MHz or the 52 MHz that we fly our planes on.

A more likely source would be a TV tower or a crane. Cranes share our 72MHz band and are able to run much more power than we can and they are right between our frequencies, they would be my choice for the source of interference.

I spent 32 years as a Telecommunications Engineer and have tracked down many types of interference and I'm sure that the near microwave freq. of cell sites will not cause a problem.
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Old 08-31-2002, 03:52 PM
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Default Concrete runways with rebar interference

We had a case of interference on 2 channels (54 & 55 IIRC) at our flying site several years ago. The source was found to be a pager repeater station that had drifted out of alignment. One of our members who knows way more about this stuff than I do tracked it down, compiled evidence of the interference, and met with the owners of the station. They confirmed his findngs and recalibrated their equipment.

Gordon
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Old 08-31-2002, 07:33 PM
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Default Concrete runways with rebar interference

Chain link fences can cause problems. I have experienced it in two sites, very repeatable and explainable. If you stand at a distance that is an odd quarter wavelength from the fence (and the reciever is directly out in front of you--at right angles to the fence) the reflected signal is 180 degrees out of phase with the desired signal and cancels it; i.e. the receiver doesn't get the signal. The dead zone is quite narrow and you will fly right through it without relalizing it at times. Several of us checked this out and could repeat the occurance at will. You could eliminate the problem by moving right up to the fence, literally lean on the fence. The farther you were from the fence, the less intense the interferance was. At our present flying site, we have a metal roof on the shelter and I get a similar glitch only at one spot in the sky when I am standing on a specific pilot station. I suspect the same probable causes that but have not checked into it that thouroughly to guarantee that is the problem.
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