Topband: Improving efficiency of a short vertical antenna?

[Herb Schoenbohm]

john battin wrote:

>  ----- Original Message ----- 
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>
>  I'm looking for suggestions for improving the efficiency of a short 
>  vertical antenna on 160M.
>
>  At present I  have top loaded this 35 ft. vertical with four 
>  25ft. long wires. They run down at a 45 degree angle.    I'd appreciate any suggestions that would help improve the   efficiency of this antenna system, keeping in mind the 35ft. height limitation.
>
>  John,
>


If you connect around the top hat wires together before the insulator 
(wire to wire to wire) you should be able to bring the base impedeance 
up a few more ohms by creating a bigger hat in the process.  (Maybe even 
double the present value of the very low base impedence.)  Also you may 
want to shorten the top hat wires to 20 or 18 feet as with a  45 down 
slope there could be more cancelation without giving you any additional 
top loading.  Here modeling or by cut and measure is the only way to be 
sure.  Also you can squeeze out some more efficiency with a properly 
constructed ground screen under the vertical.  Every little bit of 
improvement should help in your case.


Herb Schoenbohm, KV4FZ

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