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Folded Dipole 40M

Aug 1st 2013, 22:04

xof7fox

Joined: Jul 7th 2012, 16:27
Total Topics: 0
Total Posts: 0
This antenna design typically has a 300 ohm impedance. Given that a "Single Wire Dipole" has about a 72 ohm impedance, is there some advantage to working with the higher 300 ohm impedance, e.g., greater gain? I think I have read that there is generally a 'flatter' VSWR curve with a "Folded Dipole" in comparision with the "Single Wire Dipole.'
Thanks - Fred K4XXK
Aug 2nd 2013, 03:38

AA6E

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
The higher impedance of a folded dipole doesn't appreciably change the gain or pattern of the antenna. The FD does have a broader resonance, which is a plus. The choice of single wire, double (folded), or even more wires is mostly a matter of what kind of feed line you want to use and how much mechanical complexity you can deal with. (3 wires will give ~ 600 ohms feed-point impedance and even broader response). You can also look into "cage dipoles" which are not folded but offer wider response.

73 Martin AA6E
Sep 17th 2013, 23:01

xof7fox

Joined: Jul 7th 2012, 16:27
Total Topics: 0
Total Posts: 0
Thank you Martin.
Fred.

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