Status Report on using Yagi Optimizer,
I have now used the Yagi optimizer to design a 50 ohm, 23 element antenna for a 144MHz frequency. (this is the frequency used in the example provided by the author of the program).
The resulting antenna had about 16 dbi gain (ref isotropic antenna) which isn't too bad. Its impedance was quite low - about 20 ohms - compared to the target of 50 ohms. The f/b ratio and f/r ratio were about 20db. The beam width was around 25 degrees.
The optimization took around 18 hours to run on my 2666MHz Pentium II laptop.
Now I am starting the design of a 23 element antenna for 300 ohm impedance optimized over the US UHF band, ch 14 to ch 69 (470 MHz to 806 MHz). This optimizing run will probably take 60 hours. I will compare the design with a Blake DY20WB antenna which has 20 elements, but also uses a corner reflector that cannot be used in the Yagi optimizer software.
When I have done a few more runs, I will post explanations on how to use this software. Since the runs take such a long time, it might be a week or more before I post again in this thread.
DUH: Although I know something about genetic optimization, I know only enough about antennas to be dangerous. I have just learned:
UHF antennas use bow ties for the driven element so that the bandwidth of the antenna is broadened. The impedance of a bow tie likes to be around 300 ohms; the impedance of a dipole, OTOH, likes to be around 50 to 75 ohms.
So, this particular Yagi optimizer is only good for narrow bandwidth, e.g. a single UHF channel, and we should not ask the optimizer software to achieve an impedance of 300 ohms.
With the above in mind, I'm going to "get a life" and forget about the Yagi optimizer; however, if anybody wants to know how to run the program, please let me know.
[This message has been edited by cymro (edited 05-17-2001).]