[TowerTalk] HF beam antenna decision

[Peter Sundberg]

At 15:23 2004-04-16 , WD0M wrote:
>On top of my US Tower TX-455 is a SteppIR 4 element - beyond the size 
>limitations you are facing, so may I suggest a 3 element SteppIR, which 
>covers 6 meters through 20 meters, all WARC bands, and presents a 1:1 
>SWR?  I'd recommend LMR400 or RH-213 also.  

Just curious, how is the matching done on the SteppIR so that it presents
1:1 SWR over the whole range. I understand the fundamental properties to
set the length of the elements with stepper motors, but normally a yagi has
a lower impedance than 50 ohms at j0. Is the 1:1 shown on an SWR meter
built up of a complex R + j or is the feed impedance really a pure 50 ohms
resistive on all frequencies ?

73/Peter SM2CEW