On 2015-02-27 3:10 PM, john@kk9a.com wrote:
To some degree this is true but I am not sure that you can have optimum
spacing for that big of a frequency range and still maintain a constant
impedance.
There are several antenna designers who have shown that the impedance
a simple driven element is in the mid-20 Ohm range when the antenna is
tuned for maximum gain (assuming the boom is not too long for the number
of elements). That changes when extra/coupled elements are used (e.g.
OWA). SteppIR's antennas are all 23 Ohm designs with a 2.25:1 "balun".
> It would be nice to see a model.
Dig out any yagi optimizer, plug in the SteppIR element positions and
have it optimize for maximum gain with the fixed positions. You will
get a series of element lengths and performance that very closely
tracks the SteppIR specs (been there, did the exercise 10+ years ago).
73,
... Joe, W4TV
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|