[Elecraft] folded dipole of topic
Vic Rosenthal
[email protected]
Mon Dec 29 12:08:22 2003
David Schornak wrote:
> does anyone know of a math to design a folded dipole I know the
> length is 468/fMHz but what is the distance between the two wires see
> ya
If the wires are the same diameter, the impedance step up will be 4
times, regardless of the spacing. A dipole's impedance varies with the
height above ground (the ARRL Antenna Book has a chart) so the FD
impedance will come out from about 200 to 300 ohms. Note that if you
use a solid dielectric such as tv twinlead, the velocity factor of the
line becomes a factor.
If the wires are of different diameters, then the step-up varies
according to the diameters and the spacing. Again, the ARRL Antenna
Book has a chart and formula. It's slightly complicated, so I don't
remember it exactly.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco