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#1
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Antenna under fabric in welded tube ship?
I would like to put internal nav and comm antennas in a series 5
kitfox, which has a welded tube frame. Could reasonable performance be obtain with elements on the inside surface of the fabric, but out side the frame? Seems to me this is essentially mounting the antenna very close to a so-so ground plane. How much loss and alteration of the radiation pattern is likely? Would the situation improve by minimzing runs parallel to the frame tubes? Thanks! Jon |
#2
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Antenna under fabric in welded tube ship?
"Jon" wrote in message ... I would like to put internal nav and comm antennas in a series 5 kitfox, which has a welded tube frame. Could reasonable performance be obtain with elements on the inside surface of the fabric, but out side the frame? Seems to me this is essentially mounting the antenna very close to a so-so ground plane. How much loss and alteration of the radiation pattern is likely? Would the situation improve by minimzing runs parallel to the frame tubes? I'm no expert, and I am sure someone who is will chime in, but I don't think that will work worth a darn. If the antenna element within an antenna length of the frame, the fact that the frame is a part of the ground plane will interfere with the signal, or something along that effect. -- Jim in NC |
#3
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Antenna under fabric in welded tube ship?
You would get better performance with a piece of limp spaghetti inside a
copper septic tank. Jim -- "If you think you can, or think you can't, you're right." --Henry Ford "Jon" wrote in message ... I would like to put internal nav and comm antennas in a series 5 kitfox, which has a welded tube frame. Could reasonable performance be obtain with elements on the inside surface of the fabric, but out side the frame? Seems to me this is essentially mounting the antenna very close to a so-so ground plane. How much loss and alteration of the radiation pattern is likely? Would the situation improve by minimzing runs parallel to the frame tubes? Thanks! Jon |
#4
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Antenna under fabric in welded tube ship?
"RST Engineering" wrote in message
... You would get better performance with a piece of limp spaghetti inside a copper septic tank. Jim What length spaghetti? Also, would I need a field approval to install this, or is it electrically connected to the landing light? ---------------------------------------------------------------------------- --------------------- When the only tools you have are a dremel and a flat blade screwdriver, everything looks like a rounded off philips screw. |
#5
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Antenna under fabric in welded tube ship?
Jon wrote:
I would like to put internal nav and comm antennas in a series 5 kitfox, which has a welded tube frame. Could reasonable performance be obtain with elements on the inside surface of the fabric, but out side the frame? Seems to me this is essentially mounting the antenna very close to a so-so ground plane. How much loss and alteration of the radiation pattern is likely? Would the situation improve by minimzing runs parallel to the frame tubes? Thanks! Jon Jon, fact of life is that an antenna needs to approximate a dipole half a wavelength long. You can cheat, and leave off half the dipole, and use the aircraft structure as the other half dipole, however, that implies that the 1/4 wavelength monopole is mounted PERPENDICULAR to the airframe; not PARALLEL to it. I'm with Jim... |
#6
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Antenna under fabric in welded tube ship?
MikeMl wrote:
Jon wrote: I would like to put internal nav and comm antennas in a series 5 kitfox, which has a welded tube frame. Could reasonable performance be obtain with elements on the inside surface of the fabric, but out side the frame? Seems to me this is essentially mounting the antenna very close to a so-so ground plane. How much loss and alteration of the radiation pattern is likely? Would the situation improve by minimzing runs parallel to the frame tubes? Thanks! Jon Jon, fact of life is that an antenna needs to approximate a dipole half a wavelength long. You can cheat, and leave off half the dipole, and use the aircraft structure as the other half dipole, however, that implies that the 1/4 wavelength monopole is mounted PERPENDICULAR to the airframe; not PARALLEL to it. I'm with Jim... btw-on a less than 120MPH airplane, why bother trying to hide it? |
#7
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Antenna under fabric in welded tube ship?
On Apr 22, 10:33 am, Jon wrote:
Could reasonable performance be obtain with elements on the inside surface of the fabric, but out side the frame? -------------------------------------------------------------------- Yes. But only when the control tower is also inside of the fabric (but out side of the frame). Seriously Jon, if you want to radiate a good signal create a counter- poise (ie, a 'ground plane') and mount your radiating element in the middle... outside of the fabric. If you're worried about drag, spring for a composite antenna with a nicely streamlined cross-section. Otherwise, do what everyone else does and use a hunka brass welding rod in a BNC connector :-) -R.S.Hoover -(KA6HZF) |
#8
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Antenna under fabric in welded tube ship?
On Apr 22, 2:36 pm, "RST Engineering" wrote:
You would get better performance with a piece of limp spaghetti inside a copper septic tank. Jim We have a '96 American Champion 7ECA in which the factory installed the ELT antenna inside the aft fuse frame, with the antenna's whip zip-tied to a diagonal upright to keep it away from the elevator and rudder cables. I hope we never have to go looking for this airplane. This is the same outfit that sells airplanes with plugs in the tank sump drain ports. Plugs instead of quick-drain vaves. Go figure. We fixed that one immediately. Dan |
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