Using optimise (example #1)

Here we optimise for gain, F/B anbd VSWR, but set the programme up to calculate the VSWR assuming a load of 12.5 + j 0.

parrot /export/home/drkirkby/yagiuda-1.18/src % optimise -o 19 -Z 12.5 example1 1000
Will optimise insisting all selected parameters improve.
Optimising for maximum possible gain.
Optimising for maximum possible FB ratio.
Optimising for an input SWR as low as possible
    1 G= 9.65dBi,FB= 12.30dB,SL= 0.00dB,SWR= 5.18,Z= 42.42-j 29.86
    8 G= 9.71dBi,FB= 16.25dB,SL= 0.00dB,SWR= 2.54,Z= 31.00-j  4.40
  255 G= 9.88dBi,FB= 17.39dB,SL= 0.00dB,SWR= 1.87,Z= 23.06+j  2.39
  260 G= 9.94dBi,FB= 17.44dB,SL= 0.00dB,SWR= 1.78,Z= 21.97-j  2.12
  262 G= 9.96dBi,FB= 18.63dB,SL= 0.00dB,SWR= 1.62,Z= 18.32-j  4.55
  274 G= 9.99dBi,FB= 20.22dB,SL= 0.00dB,SWR= 1.30,Z= 16.25-j  0.52
  334 G=10.00dBi,FB= 20.87dB,SL= 0.00dB,SWR= 1.09,Z= 13.40+j  0.72
  426 G=10.01dBi,FB= 23.06dB,SL= 0.00dB,SWR= 1.09,Z= 11.62-j  0.58
  536 G=10.01dBi,FB= 23.11dB,SL= 0.00dB,SWR= 1.08,Z= 11.56-j  0.07
  588 G=10.01dBi,FB= 23.12dB,SL= 0.00dB,SWR= 1.06,Z= 11.87-j  0.24
  591 G=10.02dBi,FB= 23.25dB,SL= 0.00dB,SWR= 1.06,Z= 11.85+j  0.17
  613 G=10.02dBi,FB= 23.38dB,SL= 0.00dB,SWR= 1.04,Z= 12.14+j  0.23
  627 G=10.02dBi,FB= 23.55dB,SL= 0.00dB,SWR= 1.02,Z= 12.40+j  0.24
  707 G=10.03dBi,FB= 23.66dB,SL= 0.00dB,SWR= 1.02,Z= 12.44-j  0.19
  715 G=10.03dBi,FB= 23.73dB,SL= 0.00dB,SWR= 1.00,Z= 12.44+j  0.01
  757 G=10.03dBi,FB= 23.74dB,SL= 0.00dB,SWR= 1.00,Z= 12.48-j  0.02
  810 G=10.03dBi,FB= 23.78dB,SL= 0.00dB,SWR= 1.00,Z= 12.52-j  0.02
  872 G=10.03dBi,FB= 23.79dB,SL= 0.00dB,SWR= 1.00,Z= 12.52+j  0.01
The best design is in a file "example1.bes". You should check it thoroughly
and if its better than example1, copy example1.bes to example1
For your inforation, the original data on the antenna was:
Start data:G= 9.65dBi,FB= 12.30dB,SL= 0.00dB,SWR= 5.18
Final data:G=10.03dBi,FB= 23.79dB,SL= 0.00dB,SWR= 1.00
Changes:   G= 0.38dBi,FB= 11.49dB,SL= 0.00dB,SWR=-4.17
parrot /export/home/drkirkby/yagiuda-1.18/src %

As you can see, the gain went up, so did the F/B and the VSWR went down.