We have first created an antenna with
parrot /export/home/davek/yagiuda-1.16/src % first example1 5 144 145 146 0.1 5

Then calculated the antenna currents with
parrot /export/home/davek/yagiuda-1.16/src % yagi example1

Calculated its performance with
parrot /export/home/davek/yagiuda-1.16/src % output example1

and optimised it many way, but best of all was in example #4.
parrot /export/home/davek/yagiuda-1.16/src % optimise -g 17 -G 0.95 -S 0.05 -Z 12.5 example1 1000

We now check to see what the optimised antenna is like at all frequencies in the 2m ham band.

parrot /export/home/davek/yagiuda-1.16/src % yagi example1.bes
yagi compleated   0.0% f=144000000.000000 MHz
<snip>
yagi compleated 100.0% f=146000000.000000 MHz

parrot /export/home/davek/yagiuda-1.16/src % output example1.bes
output compleated    0.0%
<snip>
output compleated  100.0%

parrot /export/home/davek/yagiuda-1.16/src % cat example1.bes.dat
# Driven=1 parasitic=4 total-elements=5 design=145.000MHz
# Checked from 144.000MHz to 146.000MHz.
  f(MHz) E(deg) H(deg)  R     jX     SWR   Gain(dBi)     FB(dB)    SideLobes(dB)
  144.000 47.0  55.9  14.50 -10.05  3.599     11.722     19.267      0.000
  144.100 46.9  55.6  14.30  -9.10  3.622     11.769     18.912      0.000
  144.200 46.7  55.4  14.10  -8.14  3.649     11.817     18.504      0.000
  144.300 46.5  55.1  13.89  -7.17  3.679     11.863     18.056      0.000
  144.400 46.4  54.8  13.69  -6.18  3.713     11.908     17.583      0.000
  144.500 46.2  54.6  13.48  -5.18  3.751     11.953     17.094      0.000
  144.600 46.0  54.3  13.28  -4.16  3.793     11.996     16.596      0.000
  144.700 45.9  54.0  13.08  -3.13  3.839     12.039     16.097      0.000
  144.800 45.7  53.7  12.88  -2.08  3.889     12.079     15.601      0.000
  144.900 45.5  53.4  12.68  -1.02  3.944     12.119     15.111      0.000
  145.000 45.3  53.1  12.49   0.05  4.003     12.156     14.629      0.000
  145.100 45.1  52.8  12.30   1.14  4.067     12.191     14.157      0.000
  145.200 45.0  52.6  12.12   2.25  4.135     12.224     13.695      0.000
  145.300 44.8  52.3  11.94   3.37  4.208     12.254     13.244      0.000
  145.400 44.6  52.0  11.77   4.51  4.286     12.281     12.805      0.000
  145.500 44.4  51.7  11.60   5.66  4.368     12.305     12.376      0.000
  145.600 44.2  51.4  11.44   6.83  4.455     12.325     11.959      0.000
  145.700 44.0  51.1  11.29   8.01  4.547     12.341     11.552      0.000
  145.800 43.8  50.7  11.15   9.21  4.643     12.353     11.155      0.000
  145.900 43.6  50.4  11.02  10.43  4.744     12.361     10.768      0.000
  146.000 43.4  50.1  10.90  11.66  4.848     12.363     10.391      0.000
 

parrot /export/home/davek/yagiuda-1.16/src % more example1.bes.gai
#  f(MHz)     theta   gain-E(dBi)   G(E)-peak   phi    gain-H(dBi)  G(H)-peak
  144.0000   -90.0000    -7.5454   -19.2672  -180.0000    -7.5454   -19.2672
  144.0000    90.0000    11.7218     0.0000     0.0000    11.7218     0.0000
  144.0000   270.0000    -7.5454   -19.2672   180.0000    -7.5454   -19.2672
#  f(MHz)     theta   gain-E(dBi)   G(E)-peak   phi    gain-H(dBi)  G(H)-peak
  144.1000   -90.0000    -7.1424   -18.9119  -180.0000    -7.1424   -18.9119
  144.1000    90.0000    11.7695     0.0000     0.0000    11.7695     0.0000
  144.1000   270.0000    -7.1424   -18.9119   180.0000    -7.1424   -18.9119
#  f(MHz)     theta   gain-E(dBi)   G(E)-peak   phi    gain-H(dBi)  G(H)-peak
  144.2000   -90.0000    -6.6871   -18.5036  -180.0000    -6.6871   -18.5036
  144.2000    90.0000    11.8165     0.0000     0.0000    11.8165     0.0000
  144.2000   270.0000    -6.6871   -18.5036   180.0000    -6.6871   -18.5036
#  f(MHz)     theta   gain-E(dBi)   G(E)-peak   phi    gain-H(dBi)  G(H)-peak
  144.3000   -90.0000    -6.1936   -18.0565  -180.0000    -6.1936   -18.0565
<snip>