At 09:01 AM 1/18/99 -0500, w8ji.tom wrote:
...
>I think marketing and folklore has us all convinced stubs are lossless.
>Just like lumped components, ALL stubs have loss. Coaxial cable stubs can
>be particularly lossy. They just have so much surface area, they spread the
>heat around so the temperature rise isn't great.
Interestingly, in the W9LT/K3LR-design lazy-vee parasitic array, the losses
in the floating feedlines of the non-driven dipoles (which are
open-circuited stubs) actually improve F/B ratio substantially (though at
some cost in gain). You can see the change dramatically if you model the
feedlines as transmission lines (which are lossless in NEC-2) and then
replace them with loads of the appropriate X and R values.
73, Pete Smith N4ZR
n4zr@contesting.com
Loud is.
--
FAQ on WWW: http://www.contesting.com/towertalkfaq.html
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|