[TowerTalk] Yagi mounting and modeling software

[Doug Snowden]

A recent post made me think of this question. I have been playing with
the free MMANA modeling software, as well as the older Yagimax.  My
first models were the usual dipole etc.  I started playing with yagis,
and one thing I tried to do was to model a
Hygain 204ba.  I can arrive at decent pattern, f/b, gain etc.   All of
the models I have seen seem to model the HyGain antennas with shorter
elements than the actual measurements from a Hygain assembly manual.
The actual measurements are a foot or more longer for, say the
reflector than the modeled antenna.   Other elements are similar in
difference. The K4VX Yagimax seems to agree with the modeling files I
see.   The ARRL has a ZIP file with all of the HyGain designs.  The
models include the 3 inch boom mounting dimensions too.  I have
changed element tapers. and this does not have anywhere near the
influence to change the results that I see. I am confused, but, as
usual, it will be something I have overlooked.  Would this have
something to do with the Beta (hairpin) match that HyGain uses?

Doug, N4IJ