[TowerTalk] TH6-DXX Band segment settings

[Jim Brown]

On 11/7/2024 12:52 PM, Richard Karlquist wrote:
> Consider
> this:  the TH6DXX has 6 or maybe 7 dB gain over a dipole at best.  Using
> a tuner, the gain will never be less than a dipole.  So it will work as
> well as a dipole.  For casual operation, that may work just fine.  It's
> only down 1 S unit.

What Rick is getting at here is that element dimensions and spacing is 
what determines DIRECTIVITY and pattern IN THREE DIMENSIONS, and those 
three setting optimize FORWARD GAIN for those frequency ranges. The 
antenna will WORK outside those ranges, but with much less gain. This is 
the kind of error you make when SWR is your only criteria. The antenna 
"loads," it radiates, but the pattern isn't great.

It's worth spending time with a good modeling program to study this with 
the many designs that are included with the ARRL Antenna Book, as well 
as Dean Straw's (N6BV)  YW software. It plots gain, FB, and, after using 
the software to compute a match, SWR vs. frequency, I've used it to 
design a few monobanders, built from aluminum and other hardware 
scrounged from neighbor hams. I learned how to enter data by studying 
the many provided files for designs. There is, no doubt, other software. 
This is one I know. I also know and use NEC a lot, but not for Yagis.

73, Jim K9YC