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Oct 24, 2013, 02:31 PM
Registered User
Discussion

Bend in antenna - field effect?


Hi, I have a HK 2.4GHz receiver with a simple wire for an antenna. Does anyone know how the EM field will change if I bend the antenna/wire, or route it with two 90 degree turns?

The reason I ask, is that I would like to have the antenna make a 90* turn to go through my plane's foam to it's external surface, then another 90* turn to run along its outer surface. Any thoughts on how that will affect signal transmission? Do the antennas have to be perfectly straight?

Sort of a second question, does EPO foam attenuate the signal much? Should I just leave it inside the foam, rather than trying to make two turns to get it to the exterior?

Sorry if that is confusing or doesn't make sense. Any advice appreciated!

Harry
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Oct 24, 2013, 02:50 PM
Registered User
The antenna is only that last 28 to 32 mm (the part that looks like a bare wire). The material that connects that antenna to the receiver is a coaxial cable ( a conductor inside a hollow metallic tube separated by an insulation--Google Coax for a good explanation). This cable can be gently bent if you are careful to not get a crimp in it or deform it in any way. Any change in the dimensions between the inner conductor and that outer sheath can have very undesirable effects on the reception but gentle curves will be okay.
Last edited by Rodney; Oct 24, 2013 at 02:51 PM. Reason: correct terminalogy
Oct 24, 2013, 03:01 PM
Registered User
Rodney - thanks so much.

Any idea how much EPO foam (Bixler2) attenuates the signal? Is it ok to just leave it inside, or worth it to run outside the foam?
Oct 24, 2013, 06:38 PM
Registered User
Wintr's Avatar
Quote:
Originally Posted by Harry_RC
Rodney - thanks so much.

Any idea how much EPO foam (Bixler2) attenuates the signal? Is it ok to just leave it inside, or worth it to run outside the foam?
Unless the foam is coated in a metallic paint, attenuation is near zero.
Dec 08, 2013, 03:14 PM
Registered User
If at all possible.
NEVER ,fold, bend or coil any high frequency antenna. UNLESS you can check with a manufacturer.................NEVER CUT OR SHORTEN any antenna.
Dec 08, 2013, 04:31 PM
Just call me Ῥέᾱ
Rhea's Avatar
Quote:
Originally Posted by Rodney
The antenna is only that last 28 to 32 mm (the part that looks like a bare wire). The material that connects that antenna to the receiver is a coaxial cable ( a conductor inside a hollow metallic tube separated by an insulation--Google Coax for a good explanation). This cable can be gently bent if you are careful to not get a crimp in it or deform it in any way. Any change in the dimensions between the inner conductor and that outer sheath can have very undesirable effects on the reception but gentle curves will be okay.
Quote:
Originally Posted by Wintr
Rodney - thanks so much.

Any idea how much EPO foam (Bixler2) attenuates the signal? Is it ok to just leave it inside, or worth it to run outside the foam?

Unless the foam is coated in a metallic paint, attenuation is near zero.
Ditto all of the above
Dec 08, 2013, 11:24 PM
60 years of RC flying
Daedalus66's Avatar
Quote:
Originally Posted by cyclops2
If at all possible.
NEVER ,fold, bend or coil any high frequency antenna. UNLESS you can check with a manufacturer.................NEVER CUT OR SHORTEN any antenna.
As stated previously, the antenna proper is the last 30mm or so and it should be kept reasonably straight and not cut. Coiling the connecting cable, however, is not a problem. The only risk is in kinking the cable sharply, which can easily damage it.

The reference to a "simple wire" in the original post is almost certainly wrong, as a 30mm wire would not be long enough for the two 90 degree bends described. The antenna must be coax with the last 30mm stripped.