I built the one in the ARRL QST which is an 8 elem with a 69mm bare stub on top.
Wonder if anyone can model the antenna
Just telling “ARRL QST” is not enough.
Please post more details with sketches, or post link to web page where you found it.
Sorry thought about that. Here is the link to the article, I used the same Coax as his.
The pdf linked above says bare whip is 4.5" which is 114 mm, while you said the bare whip is 69 mm. Which whip length you want in simulation?
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thought it was 69, didn’t do the calculations, its the 4.5 or 114mm
I saw your calculations of the COCO with 8 elem wondered what the 1/2 way whip does. I have mine going to 25ft of RG6 to the room. I dont have that 90
elbow he did either just a straight connection so that leaves 3db stilll in 
, have had it up over a year now
Thanks a to, kinda looks like what I am seeing . And Im 7 meters above ground I live in the Puget Sound area and with mountains on both sides, pretty well mimics whats going on. Appreciate it. For homemade Im pretty happy.
Dont think I could do much better with cantenna. Maybe flightaware antenna but not worth the money for improvement