[TowerTalk] SteppIR

[Joe Subich, W4TV]

On 2015-02-27 3:10 PM, john at 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