[Antennas] dipole question
James Duffer
[email protected]
2002年8月19日 12:13:59 -0500
snip
>>I have to disagree here George (your math is somewhat flawed above)
>A dipole is always 75ohms for argmument sake; yes it will vary +/-
>due to height above ground, etc.....BUT regardless of wire size,
>the average single wire dipole is 75ohms....a FOLDED two wire dipole
>is always then 300ohms at feed point....regardless of the Z of the wire,
>spacing, etc used in the folded dipole.
Impedance transformation will occur with different ratios of the conductor
sizes.
Re. The Guertler formula "Impedance Transformation in Folded Dipoles," J.
Brit. IRE, vol 9, Septermber 1949, p. 344
For ladder line, the conductors are normally equal radius thus
transformation is 4.
73, Jim, wd4air
...I cannot see how using 600ohm
>Z line for the dipole element makes it 2400ohms at the feedpoint...
>The Ladderline's Z used for the DIPOLE element is a moot point...
>The same rules apply to it as a std dipole or folded dipole..
>Folded dipole (conventional) is usually 300ohm Z...+/- 10-20%...
>
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