Antenna optimizers
- From: Ian White GM3SEK <gm3sek@xxxxxxxxxxxxx>
- Date: Fri, 9 Mar 2007 10:37:02 +0000
In a different thread, N5MK wrote:
I've tried some programs with "optimizers" etc, etc.. MMANA has one fer instance, and it's freeware. In many cases, I can manually churn out a better design by ignoring it, and doing it myself. I've seen a few churn out some pretty funky designs which were not even close to being optimum. Overall, I don't have much use for them. I don't need the program to hold my hand while using it.
Can we start a new discussion, specifically about optimizers?
Having used Brian Beezley's YO and AO (Yagi Optimizer and Antenna Optimizer) extensively in the past, I'm not quite as pessimistic as Mark about the value of optimizers.
If they're simply allowed to run wild, they can produce some very foolish antenna designs. Usually that is not a criticism of the automated modeling... it mostly means that, for some practical reason or another, the user would be a fool to build the thing.
On the other hand, an optimizer can be very useful for tasks that have a very simple target, so it can't go far wrong. For example: "Adjust the length of that wire to make it resonant at this frequency." That doesn't take long to do by hand, but an optimizer can also handle more complicated tasks like: "Adjust the lengths of these three interacting wires to make the antenna resonant on three different bands." Then you really start to see some benefit from the automation.
At the other end of the spectrum is the kind of complex optimization for which YO was developed. You quickly learn that you can't just say "Optimize that yagi!" Quite the opposite: to use the program at all, you are forced to think very hard about what you really mean by "optimum" - for example, how much importance you attach to forward gain, a clean pattern, a convenient feedpoint impedance, and to maintaining that good performance over a wide bandwidth. Playing with an optimizer, you quickly come to understand that it isn't possible to get the best of everything, all at the same time... which is a very valuable lesson to learn.
The same applies to all other antenna optimizers, of course; and circuit optimizers too. The learning process alone can be worth the money.
Having gone through that learning process, an automatic optimizer can then zip out some really good antenna designs in a matter of minutes - which leaves you wondering what took you so long :-) But that isn't going to happen in the first evening, or even maybe the first month.
[Sorry, I don't know how or even if you can buy AO or YO any more.]
--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
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