Using optimise (example #2)

Here we optimise for gain only, which is a bad idea.
 

parrot /export/home/drkirkby/yagiuda-1.18/src % optimise -o1 example1 1000
Will optimise insisting all selected parameters improve.
Optimising for maximum possible gain.
    1 G= 9.65dBi,FB= 12.30dB,SL= 0.00dB,SWR= 1.93,Z= 42.42-j 29.86
   15 G= 9.68dBi,FB= 15.64dB,SL= 0.00dB,SWR= 7.24,Z=  9.03-j 27.41
   59 G= 9.86dBi,FB=  9.70dB,SL= 0.00dB,SWR= 6.91,Z= 25.83-j 77.08
   62 G=12.05dBi,FB=  9.32dB,SL= 0.00dB,SWR=99.00,Z=  0.30-j119.67
   81 G=20.99dBi,FB=  3.03dB,SL= 0.00dB,SWR=99.00,Z=  0.01-j 73.43
  299 G=23.71dBi,FB=  3.24dB,SL= 0.00dB,SWR=99.00,Z=  0.00-j 67.07
  537 G=30.11dBi,FB=  3.23dB,SL= 0.00dB,SWR=99.00,Z=  0.00-j 67.60
  668 G=30.97dBi,FB=  3.01dB,SL= 0.00dB,SWR=99.00,Z=  0.00-j 68.22
  731 G=35.75dBi,FB=  3.06dB,SL= 0.00dB,SWR=99.00,Z=  0.00-j 68.04
  851 G=38.76dBi,FB=  3.05dB,SL= 0.00dB,SWR=99.00,Z=  0.00-j 68.05
  868 G=56.39dBi,FB=  3.04dB,SL= 0.00dB,SWR=99.00,Z=  0.00-j 68.04
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= 1.93
Final data:G=56.39dBi,FB=  3.04dB,SL= 0.00dB,SWR=99.00
Changes:   G=46.74dBi,FB= -9.26dB,SL= 0.00dB,SWR=97.07
parrot /export/home/drkirkby/yagiuda-1.18/src %

As you can see, it has a high theoretical gain, but the input resistance is 0.00 Ohms and it has a VSWR of over 99. The antenna would be useless.

To see what it looks like, see the file example1.bes

parrot /export/home/drkirkby/yagiuda-1.18/src % cat example1.bes
NOTES ð
FREQUENCY 145.000000
MIN_FREQUENCY 144.000000
MAX_FREQUENCY 146.000000
STEP_FREQUENCY 0.100000
ELEMENTS 5
DRIVEN 1
PARASITIC 4
ANGULAR_STEP   180.000000
#DATA_DRIVEN        x         y       length     diameter voltage(r) voltage(i)
DATA_DRIVEN     0.48181    0.00000    0.90025    0.00500    1.00000    0.00000
#DATA_PARASITIC     x         y       length     diameter
DATA_PARASITIC
                0.00000    0.00000    1.13786    0.00500 reflector
                0.46069    0.00000    0.97158    0.00500 D1
                0.83419    0.00000    0.94493    0.00500 D2
                1.15742    0.00000    0.92675    0.00500 D3
parrot /export/home/drkirkby/yagiuda-1.18/src %