By "Holy Grail" I mean a
* all-HF-band, and
* full-legal-power (incl. negligible-loss)
antenna-feedline system. -W1HIS.
Dennis, K7FL, wrote:
>>[Chuck, W1HIS] was able to find one _fixed_ setting of the tuner
>>for which the SWR on the coax (and therefore the loss) was
>>tolerably low across _all_ HF bands 80 through 10 meters....
>This is a highly intriguing idea, so simple in concept (albeit
>difficult in execution) that I'm surprised it isn't referenced in
>more literature. I have a situation that just begs for this.
>All these seem like a lot of variables. I was going to look for the
>magic horizontal lengths in EZNEC to balance pattern with
>impedance.... But as I said, this looks like a host of variables to
>juggle - could there indeed be a methodical approach to this
>Thanks Chuck - very interesting thread
See the response to Howard K2HK that I posted a half-hour ago. I
suggested using Microsoft Excel for the simultaneous multivariable
optimization, because (1) Excel has such an optimization capability;
(2) probably most hams have Excel; and (3) Excel does complex
arithmetic, so formulas representing transmission lines, simple
lumped-element networks, and series- and parallel-connected
impedances and admittances are easy to code. I've written Excel
macros even for _lossy_ transmission lines -- complex hyperbolic
functions and all.
I don't know how to model an antenna accurately in Excel. That's one
reason why I wrote that I needed accurate antenna feedpoint impedance
_measurements_. Another reason is that, even with the best available
antenna modeling programs (I use NEC-4) it's difficult to calculate
feedpoint impedance very accurately. With care you can come close,
but probably not close enough reliably to design a matching system
Thus, in my view, the chief unsolved problem is that of accurate
antenna feedpoint impedance measurement.