Speaking of Yagi optimization...

[Scott Parker K7LU]

One program for doing Yagi design is YO (Yagi Optimizer.)  You enter your target parameters (frequency, boom length, whether to optimize for forward gain or f/b ratio) and the built-in optimization algorithm will return the dimensions of the element lengths and spacings along with a free space pattern.

I'll provide a link where YO can be had, but first the bad news:

1. Sales and support for YO was terminated by the author, K6STI, decades ago (in response to widespread piracy.)

2. YO runs under MS-DOS, which means it can be run on Windows machines, but getting there can be a chore, especially on Win 7 and later.

Those inconveniences aside, here are some cool things about YO as an educational tool.  Once the design is complete, you get to see how the pattern evolves with frequency because it gives you a free space pattern not only at the design frequency, but also at the upper and lower band edges.  But that is not all.  Even though it's DOS software, it's not all text based. There's an interactive aspect to the graphics, meaning you can do things like move the elements around and watch what happens to the patterns as you do.

So, in addition to designing Yagis for you, running YO can give you a feel for Yagi behavior, just how critical (or non-critical) varying different design parameters can be and what the trade-offs are between a max-gain design and a max-f/b design.

If you think YO would be worth the hassle of getting it up and running (or if you just happen to have an old DOS box laying around, which I kind of doubt) you can get a copy here.