[Towertalk] EZNEC 3.0 question

[Bill Tippett]

OK1RI wrote:
>Can someone tell me what is the improvement from YO 6.55 to YO 7.0.

        I belive the major improvement is a routine which uses
global optimization.  In previous versions, the optimizer would
zero in on a local optimization which might not necessarily be
the best.  YO7 was well described in a July 2000 CQ Magazine
article by K6STI although one of the graphs was wrong and later
corrected.  

SM2EKM wrote:
>Problem with YO is that the calculating engine is far too simple,
you really have to be carefull with what you are doing.
In any case, I would not trust YO alone, I would confirm
my design on a program using the NEC calculating engine.

        A standard part of YO7 is verification using NEC-2 once
an optimization is reached in YO7.  You simply hit the space bar
on the keyboard and the revised figures appear almost instantly.
In the case of my KLM model, there was very minor difference between
YO7 and the NEC-2 engine.

                                                73,  Bill  W4ZV

>From YO7 Documentation:

---- YO 7.0 YAGI OPTIMIZER -------------------------------------

	        YO analyzes and optimizes Yagi-Uda antenna designs on
	your PC.  It runs hundreds of times faster than NEC- or MININEC-
	based antenna-analysis programs.  YO's mathematical model is
	more complex than the W2PV Yagi model, simpler than MININEC, and
	more accurate than either.  YO models tapered elements, mounting
	brackets, the boom, matching networks, dual driven elements, and
	conductor loss.  YO represents antennas in free space or over
	ground.  It can model two identical Yagis stacked in the H-plane
	in free space.  YO calculates mutual-impedance interactions for
	all of these cases.  It also can ignore Yagi-to-Yagi interaction
	and model large rectangular arrays of Yagis.

	        YO includes an automatic optimizer that can maximize
	forward gain and input resistance, and can minimize backlobes,
	sidelobes, and SWR.  The optimizer iteratively adjusts element
	lengths and spacings to optimize performance objectives you
	specify using parameter tradeoffs you decide.  It can perform
	both local and global optimization.

	        YO is calibrated to NEC, the reference-accuracy
	Numerical Electromagnetics Code from the Lawrence Livermore
	National Laboratory.  YO and NEC results normally differ by less
	than 0.05 dB in forward gain, a dB or two in F/B, and a couple
	ohms in input impedance.  You can invoke NEC from within YO to
	verify results.

	        YO's analysis and graphics engines use assembly language
	with pipelined floating-point code optimized for Pentium
	processors.