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[Antennaware] Simulating the W6NL 40M moxon variant

Subject: [Antennaware] Simulating the W6NL 40M moxon variant
From: "" <>
Date: Thu, 25 Feb 2010 13:51:59 -0800
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My problem: I'm working on a simulation for a M2 40M2L (shorty-forty, linear 
loading) conversion to a moxon. I'm using the W6NL 40M moxon-like design as a 
benchmark for SWR bw, and gain/fb. (trying to get similar results, but not the 
same design)

W6NL provided an AO .ant file so his can be easily simulated.

(3 links there)

I use 4nec2x, so I used it to convert the .ant to a .nec. There were some minor 
issues that I hand-corrected. (for instance, using ' in a symbol name in the 

The simulation of the W6NL moxon looks good in 4nec2x. The visual is right for 
the antenna, the gain/fb and swr bandwidth is right (very wide swr bandwidth).

BUT: the swr min is centered too low I's around 6.8Mhz..I would have 
expected it to be centered around 7.05 or 7.1, based on W6NL's presentation 

I experimented a little. I played with different grounds. The simulation is at 
70 ft. The taper schedule is done with explicit wires of different radiuses, 
it seems fine.

I'd be surprised if nec-2 is simulating this wrong, compared to AO...

So I'm assuming something is just wrong, but I can't figure out what.
It's like it's shifted down in frequency for some reason. 

If there was someone out there would could run the .ANT file exactly as W6NL 
posted it above, and say what freq they see for a SWR min, that would be really 
useful for me? I also could put my converted .nec somewhere if there was some 
other simulator that could use the .nec? (or people can recommend something I 
could use without retyping in a model?)

I'm a little worried, because I have the design for my 40M2L conversion done, 
and I think it's pretty good (got the wide bw I wanted).  nNot that much less 
than the W6NL, but has just the typical moxon look (less aluminum) and on a 
shorter boom (19-1/2') feet....But now I'm wondering if that simulation is 

I don't know if there are other simulators that could use the .nec, but I could 
provide that also (both the W6NL and mine) if anyone was interested in seeing 
what they get for me.



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