Topband: electrically shortening a tall grounded tower

[W2XJ]

I have EZNEC5 and it delivers large errors with cages.


On 9/26/09 1:10 AM, "Bob Kupps" <n6bk at yahoo.com> wrote:

> EZNEC 5. Regardless of my inability to model I would be interested in any
> practical solutions that have already been tried and known to work.
> Thanks 73
> Bob 
> 
> --- On Sat, 9/26/09, W2XJ <w2xj at nyc.rr.com> wrote:
>> 
>> From: W2XJ <w2xj at nyc.rr.com>
>> Subject: Re: Topband: electrically shortening a tall grounded tower
>> To: "Bob Kupps" <n6bk at yahoo.com>, "topband" <topband at contesting.com>
>> Date: Saturday, September 26, 2009, 11:56 AM
>> 
>> What software are you using? Often modeling software can not handle cages.
>> 
>> 
>> On 9/25/09 11:50 PM, "Bob Kupps" <n6bk at yahoo.com
>> </mc/compose?to=n6bk at yahoo.com> > wrote:
>> 
>>> > Hi
>>> > Is there any effective way to electrically shorten a tall grounded tower
>>> to
>>> > 1/4 wave? I tried modeling a 1/4 wave cage surrounding the tower but it
>>> still
>>> > shows a lot of current in the protruding section with resulting high angle
>>> > radiation. Then I tried modeling a 1/4 wave stub above the cage grounded
>>> at
>>> > the top to the central tower which appeared to turn it into a dipole and
>>> still
>>> > significant current above the stub. I was also thinking of using an
>>> external
>>> > parallel resonant trap/choke but would this actually work when situated at
a
>>> > zero current point at the far end of a 1/4 wave monopole?
>>> > Thanks and 73 Bob N6BK/HS0ZIA
>>> > 
>>> > 
>>> >       
>>> > _______________________________________________
>>> > Topband mailing list
>>> > Topband at contesting.com </mc/compose?to=Topband at contesting.com>
>>> > http://lists.contesting.com/mailman/listinfo/topband
>> 
>> 
> 
>