[TowerTalk] how do you model a hairpin match?

[StellarCAT]

Hello Joe,

I figured it out. Or found out where to get the answer. Jeff had said that AutoEZ would do this – so I read over their documentation and I see it is done using a transmission line and not an inductance. With that knowledge I got a nice match to 50 ohms with very good SWR. Now if I only knew how accurate the model is since I can’t seem to model any ‘lump’ caused by the mounting bracket. I felt good when I entered the manual dimensions and with no changes other than a very slight change in the driven element length I got excellent results – comparing almost exactly to the manual values.... but now I’m not so confident since I don’t have the larger diameter that the bracket represents. 

I’m also a bit amazed at how sensitive some of these values are. That too concerns me a bit. If I change say the first directors length by 1/2” total it makes a noticeable difference in performance – so that doesn’t bode well since I’ve not included anything for the bracket. 

Any experts out there have a little time that I might talk to them on how to best do some of these things and feel confident I can make an antenna that will perform as the model results would suggest? I’m not looking at a test range here ... I don’t want to “hope” that it does...  just want to know it will work. Or is that asking too much? 

Gary 
K9RX