On 9/14/14, 2:47 PM, Doug Smith wrote:
You can match both 160 and 80 with a single “modified” L-Network. It would
have three components rather than just two. There would be no switching required moving from
160 to 80.
But, you’d likely need TWO of these networks — one for the bottom end of the
bands and one for the top end of the bands. With remote switching to flip between them.
Theoretically, one can design a network with a sufficient number Ls and
Cs to get good match anywhere. It's not quite as simple as two narrow
band networks with a switch, but it will be the same number of total
components.
There's a fair amount of literature in IEEE Trans on Ant and Prop from
the 60s and similar journals with the equations and design principles.
Look for "broadband matching network". I seem to recall seeing papers
about techniques to match the whole HF band into a dual resonance whip
antenna without relying on a big amplifier and loss.
One has to watch out for pathological scenarios with a lot of loss, but
these days, with computers to do the model, it's fairly straightforward
to do the optimization.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|