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Old May 23rd 05, 01:41 PM
Cecil Moore
 
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Richard Clark wrote:

" wrote:
What could be the possibl;e reasons for the high SWR I am seeing?


The why of your question is simple: the antenna is not tuned to the
frequency you are applying.


There's no guarantee that a tuned antenna is going to have
a feedpoint impedance of 50 ohms. Between 0.1WL and 0.33WL
in height, the same resonant dipole can have a feedpoint
impedance variation between ~20 ohms and ~100 ohms. A resonant
dipole in free space will have an SWR of ~1.5:1 using RG-213.

The reason that the SWR for any antenna is not 1:1 is that
the load (the feedpoint impedance of the antenna) is not equal
to Z0 (the characteristic impedance) of the feedline.
--
73, Cecil http://www.qsl.net/w5dxp

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