Provided by: yagiuda_1.19-5_i386 bug

NAME

       optimise - Yagi-Uda project antenna optimiser

SYNOPSIS

       optimise  [  -dhvwO  ]  [  -aangular_stepsize  ] [ -bboom_extension ] [
       -ccleanliness_of_pattern  ]  [   -eelements   ]   [   -fFBratio   ]   [
       -gGA_optimisation_method  ]  -lpercent  ]  [ -mmin_offset_from_peak ] [
       -ooptimisation_criteria ] [ -ppopulation ] [ -rresistance ] [ -sswr ] [
       -tlength_tolerance    ]   [   -xreactance   ]   [   -AAuto_gain   ]   [
       -CCurrents_similar  ]   [   -Fweight_FB   ]   [   -Gweight_gain   ]   [
       -Kkeep_for_tries     ]     [     -Pweight_pattern_cleanliness    ]    [
       -Rweight_resistance ] [  -Sweight_swr  ]  [  -Tposition_tolerance  ]  [
       -WWeighted_algorithm   ]   [   -Xweight_reactance  [  -ZZo  ]  filename
       iterations

DESCRIPTION

       The program optimise is one of a number  of  executable  programs  that
       forms  part  of  a  set of programs, collectively known as the Yagi-Uda
       project , which were designed for analysis and optimisation of Yagi-Uda
       antennas.   optimise  attempts  to  optimise  the performance of a Yagi
       antenna for one or more parameters that are considered important,  such
       as  gain,  F/B  ratio,  VSWR etc. It does this by randomly changing the
       lengths and positions, of one or  more  elements,  then  comparing  the
       performance  before and after the change.  Any improvements are written
       to a new file called filename.bes where filename is  the  name  of  the
       antenna description file created by input or first

       When  Yagi’s are designed on paper, or using this program, its possible
       that they will be almost impossible  to  build,  if  their  performance
       depends  too  critically on the dimensions. To determine if this is the
       case with a design, we run optimise with just the options ’t’ and  ’T’.
       These  specify  the  tolerance  with  which  you can build the antenna,
       expressed as a standard deviation in  mm.  In  this  case,  instead  of
       trying  to  optimise a poor design, optimise will calculate the minimum
       gain, maximum VSWR, and minimum FB ratio of a number  of  designs,  all
       slightly  different  from  the  input file. 99.7% of the components lie
       within 3 SD of the mean, so if you think you can cut elements to with 1
       mm 99.7% of the time, specify t0.33. If you can put them in the boom to
       within 3 mm 99.7% of the time, specify T1.

       If while optimise is running using the methods that require weights  to
       be  attached to the gain, FB, SWR etc, it becomes apparent, the weights
       are not optimum, its possible to pause the program  and  re-adjust  the
       weights.  If  a  file  with the name of changes is created, the program
       will pause, then request new weights are entered at the keyboard.

AVAILABILITY

OPTIONS

       -d     Print the default values of all the configureable parameters  to
              stdout.  Typing  this  option  with  any  option  that changes a
              parameter  (see  below)  will  display  the  new  value  of  the
              parameter, rather than the default.

       -h     Print a help message.

       -v     Print verbose status information.

       -w     Instead  of  optimising  at  one  fixed  frequency  (the  design
              frequency), this directs the program to optimise at  3  separate
              frequencies (lowest, design and highest) then to average data at
              all 3. This option is better for wideband antenna. Note that the
              input  impedance  printed  is  at  the  design  frequency, *not*
              averaged over 3 frequencies. Averaging an impedance,  is  likely
              to  give  a  very  misleading impression. The impedance averaged
              over 3 frequencies can be 50+i0 Ohms, even if the VSWR  is  very
              poor  over  all 3 frequencies, as the following 3 pieces of data
              show.
              Z=147 + j 300  SWR= 15.46:1
              Z=2   + j 100  SWR= 125:1
              Z=1   - j 400  SWR= 3250:1
              note in the above three cases, the average impedance is 50  +  j
              0, but average SWR is 1130:1.

       -O     Over-optimisation  allowed.   By  default,  the program does not
              over-optimise a parameter.  For  example,  an  SWR  of  1.01  is
              usually  considered  good  enough and any change, as long as the
              SWR stayed good, typically below 1.1:1, would be  allowed,  even
              if  the  SWR  rose. By default, FB’s of 27 dB, VSWR’s of 1.1 are
              acceptable. However, by using the -O option, you can insist  the
              program always improves things, no matter how good they are.

       -aAngular_stepsize
              When  optimimising  by  trying  to  get  a clean pattern,
              specifies the step size to use when looking for  features
              in  the  pattern. If its set too small, the program  runs
              slow. If its set too large, the program may miss features
              in  the  pattern,  such as a sidelobe. Then the resulting
              antenna will have poor sidelobe performance, even  though
              you  think  it  will  be  good.  The  program attempts to
              calculate  a  sensible  value,  based   on   1/10th   the
              approximate 3 dB beamwidth, if you don’t set.

       -bboom_extension
              Generally  speaking,  the  gain  of a Yagi increases with
              boom length. Hence the optimiser would often give  you  a
              Yagi  with  a  much longer boom than the input file. This
              may not be what you desire  due  to  space  restrictions.
              These  long  antennas  often have high gain, but are very
              narrow in bandwidth. The default limits  the  antenna  to
              10x the original length, which means effectively there is
              no boom length limitation.  You can adjust the percentage
              by  setting  boom_extension  to  whatever you wish.  -b30
              will limit the boom to no more than  30%  more  than  the
              original length.

       -ccleanliness_of_pattern
              Specify  the number of dB down on the peak gain to aim to
              get the pattern. Any antenna pattern  cleaner  than  this
              will  not  effect  the fitness, nor will it be considered
              any better when comparing to antenna designs. 20 dB seems
              reasonable,  so the default is 20, but this may of course
              change if it’s deceided too. Check the source code to  be
              certain (see REASONABLE_SIDELOBE in yagi.h).

       -eelements
              is  an  integer which specifies the type of elements that
              are changed in the optimisation cycle.   Possible  values
              are:
               1  -  alter only the driven element(s) length (useful to
               bring to resonance)
               2 - alter only the driven element position. Don’t change
               its length.
               4  -  alter  only  the reflector length. The position is
               always at x=0.
               8 -  alter  only  the  director  lengths.  Don’t  change
               positions.
               16  -  alter  only  the director positions. Don’t change
               lengths.
               32 - randomly adjust one element length, then makes  all
               other the same. Don’t change the positions.
               64 - apply a linear taper to the lengths.
               128  -  Set  the driven element to a resonate length. It
               may/may-not be altered after the first run, depending on
               the  whether  or  not  ’1’ is invoked too. Eg -e128 will
               make it resonate and  keep  it  there  forever.  However
               ’-e129’  will bring to resonance, then alter to maximuse
               performance.
              The elements altered is made from a logical  AND  of  the
              above,  so  for  example  to alter everything, except the
              driven element length, use -e30, since 2+4+8+16=30.   The
              default  is equivalent to -e31 , which changes everything
              possible. Note the reflector position is *never* changed.
              It’s always at x=0.

       -fFBratio
              When  optimising an antenna, consider any FB ratio
              greater than FBratio dB to be equal to FBratio dB.
              This  avoids  optimising  to a very high FB ratio,
              which is  impracticable,  as  the  bandwidth  over
              which  this  FB  ratio  will be maintained is very
              small and mechanical considerations  will  prevent
              you from constructing it with such a high FB ratio
              anyway. If this was not prevented, you might  just
              happen to get an antenna with 100 dB FB ratio, but
              poor gain and swr. Since by default all parameters
              must  improve,  the optimisation routine will most
              likely never being able to improve on the  100  dB
              FB  ratio,  so  no  improvement  will result. Most
              people would prefer to get a few extra dB of gain,
              even if the FB ratio dropped to 30 dB.

       -gGA_optimisation_method
              Use   a   genetic   algorithm.  With  the  genetic
              algorithm, the program does not take  any  account
              any  of  the initial lengths/positions of elements
              specified in the input file. Rather  it  works  by
              initialising  a  number of different antenna, then
              computing a ’fitness’ value for each.  The fitness
              value can depend on the gain, FB, real part of the
              input  impedance,  reactive  part  of  the   input
              impedance, VSWR or the level of the sidelobes. The
              integer after the g tells the  optimiser  what  to
              consider.  -g1  Use gain
              -g2  Use FB
              -g4  Use R
              -g8  Use X
              -g16 Use the SWR
              -g32 Use the level of the sidelobes.

              You can use a logical AND of these, so for example
              -g49 will use a genetic algorithm, optimising  for
              gain,    swr    and    sidelobe    level,    since
              1(gain)+16(SWR)+32(sidelobe level)=49.

       -lpercent
              is  a  parameter  (floating  point  number)  which
              specifies  the  maximum  percentage  change in the
              positions  or  lengths  of  an  elements  at  each
              iteration.  If  the option is not used, it will be
              set internally at 10% for the  first  25%  of  the
              iterations,  1%  for  the  next  25%, 0.1% for the
              third 25% of the iterations and 0.01% for the last
              25% of the iterations. If set to a positive number
              x (eg optimise -l 0.3 145e10) then the  percentage
              will  be set at x% for 25% of iterations, x/10 for
              the  next 25%, x/100 for the next  25  and  x/1000
              for  the  last  25%. If set to a negative number y
              (eg optimise -l -0.5 145e10)  then  the  paramters
              will  stay  fixed at y% (in this example 0.5%) all
              the time.

       -mmin_offset-from_peak
              Sets the minimum  angle  in  degrees  offset  from
              theta=90  degrees,  where the side lobes start and
              the main lobe finishes. The higher the  gain,  the
              smaller  it should be. It is set internally if not
              set on the command line.

       -ooptimisation_criteria
               1 -  Assume better if the gain has increased.
               2 -  Assume better if the front to back ratio has
               improved.
               4  -  Assume better if the real part of the input
               impedance is closer to the value that the program
               was  compiled  for, or set using the ’-Z’ option.
               This will usually be 50 Ohms, but you may wish to
               set  this  to  12.5  Ohms if you use a 4:1 balun.
               Generally you can get higher gain from a Yagi  if
               you  allow  the  input  impedance to fall, but of
               course feeding it becomes more difficult.
               8 -   Assume  better  if  the  magnitude  of  the
               reactive  component  of  the  input  impedance is
               lower (ie. the antenna is nearer resonance).
               16 - Assume better if the VSWR is lower.
               32 - Assume better if the level of all  sidelobes
               is lower.
              The  optimisation_criteria  may  be  formed from a
              logical AND  of  these  numbers,  so  for  example
              choosing -o19 will only consider a revised antenna
              better than the previous, if the SWR, gain and F/B
              ratio have all simultaneously improved.

              Clearly an antenna which originally had 12 dB gain
              and 1.01:1 VSWR but then changes to 20 dB  gain  @
              1.02:1  VSWR, would to most people be better, even
              though  the  VSWR  has  increased.   By   default,
              optimise  only  optimises to sensible maximums, so
              to not let the optimisation stall prematurely.  By
              running  optimise  with  no arguments, the program
              will list  the  limits  of  acceptability.   These
              might  be  typically  F/B  ratio  >  27 dB, VSWR <
              1.1:1, magnitude of input reactance  less  than  5
              Ohms  and  the  real  part  of the input impedance
              within 5 Ohms of  Zo.  Choosing  -o19  (1+2+16=19)
              will  optimise  for  gain  (since  G=1), FB (since
              FB=2) and SWR (Since SWR=16), but would consider a
              higher  gain  and  FB  ratio antenna better than a
              previous one, even if the SWR rose, as long as  it
              stayed   below   1.1:1   (or  as  was  set  during
              compilation). The default behaviour  (no  options)
              is   equivalent   to  -o37  which  optimiseas  for
              gain(1), the real part of the  input  impedance(4)
              and  sidelobes(32)  but this may be changed at any
              time, so type optimise -d  to  check  the  current
              settings.  If you insist on the program optimisang
              for the very best of all selected parameters,  use
              the  -O option too, but be warned the optimisation
              will probely stick  once  it  gets  one  parameter
              really good.

       -ppopulation
              This  determines the initial population used  with
              the genetic algorithm.

       -rresistance
              When optimising an  antenna,  consider  any  input
              resistance  closer  to  Zo  (usually 50 Ohms) than
              resistance Ohms  to  be  acceptable.  This  avoids
              optimising to an input resistance too close to Zo,
              which is  impracticable,  as  the  bandwidth  over
              which  the input resistance could be maintained is
              very  small  and  mechanical  considerations  will
              prevent  you  from  constructing  the antenna with
              such an ideal input resistance. If  this  was  not
              prevented, you might just happen to get an antenna
              with an input resistance of  50.000001  Ohms,  but
              poor gain, FB and possibly even a poor swr, if the
              antenna is well  away  from  resonance.  Since  by
              default   all   parameters   must   improve,   the
              optimisation routine will get  most  likely  never
              being  able  to improve on the antenna, whereas we
              might be happier with a few more dB gain,  if  the
              input  resistance  went to 50.1 Ohms. It should be
              noted that the default optimisation routine  never
              uses the input resistance directly (only VSWR), so
              this option cant be used without the  ’-o’  option
              to  optimise for other than the default parameters
              (gain, VSWR and FB ratio).

       -sswr  When optimising an antenna, consider any SWR  less
              than swr to be equal to swr This avoids optimising
              to a very low swr, which is impracticable, as  the
              bandwidth  over  which  such  a  low  swr could be
              maintained would  be  very  small  and  mechanical
              considerations  will prevent you from constructing
              such  an  antenna  anyway.  If  this  is  was  not
              prevented, you might just happen to get an antenna
              with an swr of 1.000000000001:1, but poor gain, FB
              ratio.   Since  by  default  all  parameters  must
              improve, the optimisation routine will most likely
              never  being  able to improve on the antenna, even
              though in practice you would like  to  get  a  few
              extra  dB of gain if the SWR would rise to 1.02:1.
              The  default  was  equivalent  to  -s1.1  but  run
              optimise   -d   to  display  this  and  any  other
              defaults.

       -tlength_tolerance
              length_tolerance is the standard deviation  in  mm
              of  the  accuracy with which you can cut elements.
              Since 99.7% of elements will be  with  3  standard
              deviations  of  the mean length (stats theory says
              this), set -t0.2 if virtually all (well 99.7%)  of
              elements  are  within  3x0.2=0.6 mm of the correct
              length. This option *must* be used with  the  ’-T’
              option  and  can’t  be used with any other options
              apart from

       -xreactance
              When optimising an  antenna,  consider  any  input
              reactance  of less than reactance to be reactance.
              This avoids over optimising the reactance, at  the
              expense of something else.

       -Aauto_gain
              When  the  auto_gain  option  is used. the program
              maximes the gain  of  the  antenna  (ignoring  all
              other  parameters  such  as  SWR, FB ratio etc) by
              adjusting the length (not position) of one element
              only.  -A-1  will  maximuse the gain, by adjusting
              the length of the reflector, -A0 will maximise the
              gain   by  adjusting  the  length  of  the  driven
              element.  Its  generally  *not*  a  good  idea  to
              maximise the gain by adjusting the driven element,
              but the program lets you  do  it,  but  using  the
              option  -A0.  Using  -A1  will  maximise  gain  by
              adjusting the length of the  first  director,  -A2
              the  second  director  and  so  on, up to the last
              director. You must check carefully that the  input
              impedance  in  particular  does  not fall to silly
              values if you use this option. On a yagi with many
              elements  (>  10  or  so),  you  can pretty safely
              maximise the 8th or more director, but doing it on
              the  reflector,  driven element or early directors
              often leads to silly input impedances - so beware!
              Note,  no  matter how many iterations you specify,
              this process is only done  once.Its  unlikely  you
              will  be able to do it again, without things going
              out of hand, but if you must do it, you  must  re-
              run ’optimise’ again.

       -Ccurrents_similar
              If  this option is used, where currents_similar is
              an integer, the program looks to make the currents
              in  the  last currents_similar elements as similar
              as possible. It computes the sum of the squares of
              the  deviations  of  the  absolute  values  of the
              element currents from the mean. If this falls, and
              the  criteria specified with the -W option is also
              satisfied, the antenna is  considered  better.  If
              currents_similar  is three less than the number of
              directors, it tries to make the  currents  in  the
              the  directors  (but  ignoringing the first 3) all
              similar.  If  currents_similar  is  equal  to  the
              number  of  directors,  it  tries  to make all the
              directors    have     similar     currents.     If
              currents_similar  is  one  more than the number of
              directors, it tries to make all the directors  and
              the    reflector   have   similar   currents.   If
              currents_similar is equal to the total  number  of
              elements, then it fails with an error message.

       -Fweight_FB
              is   the   floating  point  number  (default  1.0)
              specifying the weight to attach to the FB ratio of
              the  antenna  when  using  the  ’-W’ option, which
              calculates a fitness for the antenna based on  one
              or  more  parameters  (FB, gain, input resistance,
              input  reactance,  SWR,  cleanliness  of   antenna
              pattern).  The  ’-F’  option  is  similar  to  the
              options -G, -P, -R, -S, -X (which specify  weights
              for  gain,  pattern cleanliness, input resistance,
              SWR and  input  reactance).   When  using  the  -W
              option  the  exact  algorithm  used to compute the
              fitness (and hence the effect of  this  parameter)
              is best checked by looking at the source code (see
              perform.c). This is one area of  constant  program
              improvement/changes/development,  so its difficult
              to say  exactly  the  effect  the  parameter  has.
              However,  increasing  the  weight  of  a parameter
              (using the -F, -G, -R, -S or -X options) will make
              the  associated parameter have a greater effect on
              the fitness.  However, unless you optimise  for  a
              high FB ratio with the -W option, then setting the
              -F  option  will  have  no  effect.  For  example,
              setting  the options -F2.5 -W1 is a complete waste
              of time. There you have used  the  -W1  option  to
              optimise  only  for gain (see -W option section of
              man page) but have changed the weight  of  the  FB
              ratio  from its default 1.0 to 2.5. If you are not
              optimising for FB ratio, the weight you attach  to
              it is irrelavent.

       -Gweight_gain
              is   the   floating  point  number  (default  1.0)
              specifying the weight to attach to the gain of the
              antenna   when   using   the  ’-W’  option,  which
              calculates a fitness for the antenna based on  one
              or  more  parameters  (FB, gain, input resistance,
              input  reactance,  SWR,  cleanliness  of   antenna
              pattern).  The  ’-G’  option  is  similar  to  the
              options -F, -P, -R, -S, -X (which specify  weights
              for   FB   ratio,   pattern   cleanliness,   input
              resistance, SWR and input reactance).  When  using
              the  -W option the exact algorithm used to compute
              the  fitness  (and  hence  the  effect   of   this
              parameter)  is  best  checked  by  looking  at the
              source code (see perform.c). This is one  area  of
              constant  program improvement/changes/development,
              so its difficult to say  exactly  the  effect  the
              parameter has. However, increasing the weight of a
              parameter (using the -F, -G, -R, -S or -X options)
              will make  the associated parameter have a greater
              effect  on  the  fitness.   However,  unless   you
              optimise for gain with the -W option, then setting
              the -G option will have no  effect.  For  example,
              setting  the options -G2.5 -W2 is a complete waste
              of time. There you have used  the  -W2  option  to
              optimise  only for FB ratio (see -W option section
              of man page) but have changed the  weight  of  the
              gain  from  its default 1.0 to 2.5. If you are not
              optimising for gain, the weight you attach  to  it
              is irrelavent.

       -Kkeep_for_tries
              keep_for_tries  is  the  number  of  tries for the
              optimise to persist using the original  data  file
              as the starting point for optimisation. By default
              it is 1, which means the program immediately looks
              from a new position once a better one is found. It
              is theeoretically possible that this might  result
              in  a  quick,  but poor local maximum. If however,
              keep_for_tries is 1000, it will stay at a position
              for  1000  iterations  after finding the last best
              result, before considering this  to  be  a  global
              optimum.  Then  it starts for the new position. In
              practice, I have found this option to make matters
              worst  in  most  cases.  It was added to avoid the
              local-minimum  problem,   but   it   appears   the
              optimisation  surface is pretty smooth, so it just
              slows the program, without gaining  much.  Anyway,
              it  can  stay  as an option, but check the results
              with/without carefully before using extensively.

       -Ppattern_cleanlyiness
              is  the  floating  point  number   (default   1.0)
              specifying  the  weight to attach to the cleanness
              of the antenna pattern when using the ’-W’ option,
              which  calculates  a fitness for the antenna based
              on  one  or  more  parameters  (FB,  gain,   input
              resistance,  input  reactance, SWR, cleanliness of
              antenna pattern). The ’-P’ option  is  similar  to
              the  options  -F,  -G,  -R,  -S, -X (which specify
              weights for FB ratio, gain, input resistance,  SWR
              and  input  reactance).   When using the -W option
              the exact algorithm used to  compute  the  fitness
              (and  hence  the effect of this parameter) is best
              checked  by  looking  at  the  source  code   (see
              perform.c).  This  is one area of constant program
              improvement/changes/development, so its  difficult
              to  say  exactly  the  effect  the  parameter has.
              However, increasing  the  weight  of  a  parameter
              (using the -F, -G, -R, -S or -X options) will make
              the associated parameter have a greater effect  on
              the  fitness.   However, unless you optimise for a
              clean antenna pattern with  the  -W  option,  then
              setting  the  -P  option  will have no effect. For
              example,  setting  the  options  -P2.5  -W1  is  a
              complete  waste  of  time. There you have used the
              -W1 option to  optimise  only  for  gain  (see  -W
              option  section  of man page) but have changed the
              weight of the pattern cleanliness from its default
              1.0  to 2.5. If you are not optimising for a clean
              radiation pattern, the weight you attach to it  is
              irrelavent.   With appropiate use of the -W option
              (eg -W49 for gain, SWR and a clean  pattern),  the
              computer  program  finds  the  level  of  the most
              significant sidelobe, wherever it may  be  outside
              the  main  bean. It then optimises to reduce this.
              The -P option tells it how much weight to  put  on
              reducing this sidelobe.

       -Rweight_resistance
              is   the   floating  point  number  (default  1.0)
              specifying the weight to attach to  the  obtaining
              an  input  resistance  close  to Zo on the antenna
              when using the ’-W’  option,  which  calculates  a
              fitness  for  the  antenna  based  on  one or more
              parameters  (FB,  gain,  input  resistance,  input
              reactance,  SWR,  cleanliness of antenna pattern).
              The ’-R’ option is similar to the options -F,  -G,
              -P,  -S,  -X  (which specify weights for FB, gain,
              pattern cleanliness,  SWR  and  input  reactance).
              When  using the -W option the exact algorithm used
              to compute the fitness (and hence  the  effect  of
              this  parameter) is best checked by looking at the
              source code (see perform.c). This is one  area  of
              constant  program improvement/changes/development,
              so its difficult to say  exactly  the  effect  the
              parameter has. However, increasing the weight of a
              parameter (using the -F, -G, -R, -S or -X options)
              will make  the associated parameter have a greater
              effect  on  the  fitness.   However,  unless   you
              optimise  for  an an input resistance close to Zo,
              with the -W option, then  setting  the  -R  option
              will  have  no  effect.  For  example, setting the
              options -R2.5 -W1 is a  complete  waste  of  time.
              There  you  have  used  the -W1 option to optimise
              only for gain (see -W option section of man  page)
              but have changed the weight of the resistance from
              its default 1.0 to 2.5. If you are not  optimising
              for  an  input  resistance close to Zo, the weight
              you attach to it is irrelavent.

       -Sweight_swr
              is  the  floating  point  number   (default   1.0)
              specifying  the weight to attach to the SWR of the
              antenna  when  using  the   ’-W’   option,   which
              calculates  a fitness for the antenna based on one
              or more parameters (FB,  gain,  input  resistance,
              input   reactance,  SWR,  cleanliness  of  antenna
              pattern).  The  ’-S’  option  is  similar  to  the
              options  -F, -G, -P, -R, -X (which specify weights
              for   FB,   gain,   pattern   cleanliness,   input
              resistance  and  input reactance).  When using the
              -W option the exact algorithm used to compute  the
              fitness  (and  hence the effect of this parameter)
              is best checked by looking at the source code (see
              perform.c).  This  is one area of constant program
              improvement/changes/development, so its  difficult
              to  say  exactly  the  effect  the  parameter has.
              However, increasing  the  weight  of  a  parameter
              (using the -F, -G, -R, -S or -X options) will make
              the associated parameter have a greater effect  on
              the fitness.  However, unless you optimise for SWR
              with the -W option, then  setting  the  -S  option
              will  have  no  effect.  For  example, setting the
              options -S2.5 -W1 is a  complete  waste  of  time.
              There  you  have  used  the -W1 option to optimise
              only for gain (see -W option section of man  page)
              but  have  changed  the weight of the SWR from its
              default 1.0 to 2.5. If you are not optimising  for
              SWR, the weight you attach to it is irrelavent.

       -Tposition_tolerance
              position_tolerance is the standard deviation in mm
              of the accuracy with which you can  cut  elements.
              Since  99.7%  of  elements will be with 3 standard
              deviations of the correct position  (stats  theory
              says  this), set -T2 if virtually all (well 99.7%)
              of elements are within 3x2=6  mm  of  the  correct
              position.This  option *must* be used with the ’-t’
              option and can’t be used with  any  other  options
              apart from

       -WWeighted_algorithm
              Try to get an antenna which is better according to
              a weighted combination of parameters, rather  than
              require them all to improve. The integer specifies
              what to consider in the weighted parameters.
              W1 Gain.
              W2 FB
              W4 R
              W8 X
              W16 SWR
              W32 SIDE_LOBE
              You can  logically  AND  these  together,  so  for
              example   -W3   will  optimise  using  a  weighted
              combination of gain  and  FB.  -W49,  will  use  a
              weighted  combination  of  gain,  swr and sidelobe
              leve, since 32+16+1=49.

       -Xweight_reactance
              is  the  floating  point  number   (default   1.0)
              specifying the weight to attach to achieving a low
              input reactance on the antenna when using the ’-W’
              option, which calculates a fitness for the antenna
              based on one or more parameters (FB,  gain,  input
              resistance,  input  reactance, SWR, cleanliness of
              antenna pattern). The ’-X’ option  is  similar  to
              the  options  -F,  G, -P, -R and -S (which specify
              weights for FB ratio, gain,  pattern  cleanliness,
              input  resistance,  and  SWR).   When using the -W
              option the exact algorithm  used  to  compute  the
              fitness  (and  hence the effect of this parameter)
              is best checked by looking at the source code (see
              perform.c).  This  is one area of constant program
              improvement/changes/development, so its  difficult
              to  say  exactly  the  effect  the  parameter has.
              However, increasing  the  weight  of  a  parameter
              (using the -F, -G, -R, -S or -X options) will make
              the associated parameter have a greater effect  on
              the  fitness.   However, unless you optimise for a
              low input  reactance  with  the  -W  option,  then
              setting  the  -X  option  will have no effect. For
              example,  setting  the  options  -X2.5  -W1  is  a
              complete  waste  of  time. There you have used the
              -W1 option to  optimise  only  for  gain  (see  -W
              option  section  of man page) but have changed the
              weight of the reactiance from its default  1.0  to
              2.5.  If  you  are  not optimising for a low input
              reactance,  the  weight  you  attach  to   it   is
              irrelavent.

       -ZZo
              Zo  is  the  characteristic  impedance  used  when
              evaluating the VSWR,  reflection  coefficient  and
              other  similar calculations. The optimiser usually
              tries to bring the input impedance of the  antenna
              to this value. It is set by default to 50 Ohms, so
              the default is equivalent to -Z50 but may  be  set
              to  any  positive  number. Set to 12.5 Ohms if you
              are going to feed the antenna with  a  4:1  balun.
              Generally  speaking,  the  gain  of  a Yagi can be
              higher for low input  impedances,  but  of  course
              such antennas are more difficult to feed.

       filename
              This  is  the  name  of  the  file  containing the
              antenna description. It is expected  to  be  in  a
              format  created  by  either  input  or first - two
              other programs in the Yagi-Uda project.   This  is
              an ASCII text file.

       iterations
              is  an integer specifying the number of iterations
              for the optimiser to perform to  try  to  get  the
              best  antenna.  Time  will  limit  the  number you
              choose. 1000 iterations of a 1ele yagi takes about
              5  seconds, a 6ele approximately 60 seconds, an 11
              element 350 seconds, a 20 element 1030 seconds,  a
              33ele  2440  seconds,  a  50element  5400 seconds,
              100ele 21320 seconds all on an old  25MHz  486  PC
              with  no external cache.  When using the -A option
              the iterations is automatically set internally  so
              only one attempt is made.  When using the ’-t’ and
              ’-T’ options, iterations specifies the  number  of
              iterations  to  attempt to get a poorer design, to
              check the  sensitivity  of  the  design  to  small
              manufacturing tolerances.

EXAMPLES

       Here are a number of examples of using optimise.

       1) optimise 5ele 1000

       Here  the  file  5ele will be optimised using the default
       system for 1000 iterations. The default  might  typically
       require  gain, FB and SWR to all improve, but this may be
       changed at any time. In any case, the program  tells  you
       what its optimising for. By default the program will only
       optimise to the selected parameters are good,  not  over-
       optimising any one at the detrement of the others.

       2) optimise -b30 -f50 -s2 5ele 1000

       This  is similar to above, but the boom can not extend by
       more than 30% from its  original length, FB ratios  above
       50  dB  are considered acceptable, as are SWR’s less than
       2:1. The optimised resultant antenna is  likely  to  have
       better FB ratio, but poorer SWR than in (1) above.

       3) optimise -o1 5ele 1000

       This  will simply optimise 5ele for maximum forward gain.
       The resultant antenna may have a poor  FB  ratio  and  is
       likely  to  have  an unacceptably low input impedance and
       hence high VSWR. This is not a very  sensible  method  of
       optimisation.

       4) optimise -W49 -l7 5ele 10000

       This   will  optimise  the  file  5ele  using  for  10000
       iterations. It will require that the weighted performance
       of  the  antenna  in  three  important  parameters (gain,
       sidelobe level and SWR) improves from one design  to  the
       next.  One  or two parameters can actually get worst from
       one design to the next, but the weighted  performance  is
       better.  The  positions  of  the  elements  or lengths of
       elements  will  not  change  by  more  than  7%  in  each
       iteration.

       5) optimise -g -S30 -G50 -F20 -p1500 5ele 10000

       This   will  optimise  the  file  5ele  using  a  genetic
       algorithm. 1500 antennas will be randomly  designed.  The
       performance  of  each  of  these  will  measured  using a
       ’fitness’ function, weighted 30% to SWR, 50% to gain  and
       20%  to FB ratio. The probability of breading from a pair
       of antennas is proportional to the fitness function.

       6) optimise -w atv_antenna 10000

       This will  optimise  the  file  atv_antenna  for  a  best
       average  performance  over  a  wide  band.  The  progrram
       calculates the gain, FB and  SWR  at  three  frequencies,
       then  computes  an  average  (mean)  performance  of  the
       antenna over the band. N iterations will take 3x as  long
       to  execute  as  N iterations on the same antenna without
       the ’-w’ option.

       7) optimise -t0.1 -T1  good_design 100

       This  will  take  the  file  good_design  and  make   100
       different  antennas  from  it, to simulate the effects of
       building tolerances. Each element is assumed to be cut so
       that  the  mean  error  of  all  elements  is 0 mm, but a
       standard deviation of 0.1 mm, so 68.4% of element lengths
       are  within 0.1 mm, 95.4% within 0.2 mm and 99.7% with in
       0.3 mm. The accuracy of placing elements along  the  boom
       is  much  lower,  so  here  we  have specified a standard
       deviation of 1.0 mm, so  68.6%  of  elements  are  placed
       within 1 mm of the correct position, 95.4% within 2 mm of
       the correct position etc.  The program  will  report  the
       *worst*  performances  achieved.  If the performance dips
       too mush, then you either need to build them  better,  or
       get a design that’s less critical!

STOPPING

       Optimise   will  stop  after  the  number  of  iterations
       specified in the parameter iterations.  It will also stop
       if  a  file  stop  exits  in the current directory of the
       executable optimise This  file  can  of  course  only  be
       created  using  a  multi-tasking operating system such as
       Unix. It is  *not*  advisable  to  stop  the  program  by
       hitting  the DEL key (Unix) or CONTROL-C (DOS), as one of
       the files may be open at the time, resulting in an  empty
       file.  Files  are  not open for any longer than necessary
       (they are closed immediately after writing to  them),  so
       this is not a likely occurrence, but can still occur.

LIMITATIONS

       I’m  not  aware  of  any  limitations,  apart  from  that
       filenames,  including  full   path,   can’t   exceed   90
       characters.

FILES

       filename           Antenna description, created by input or first.
       filename.up    Update file, listing achievements of optimise.
       filename.bes       Best file, containing the best design to date.
       changes         File that causes the program to pause to re-adjust weights.
       stop            File that stops optimisation process.

SEE ALSO

       first(1),   input(1),   output(1),   yagi(1),   first(5),
       input(5) output(5) and optimise(5).

PLATFORMS

       Both DOS and Unix  versions  have  been  built.  The  DOS
       version as distributed requires a 386 PC with a 387 maths
       coprocessor.

       Although I have  altered  the  source  to  make  it  more
       compatible  with  DOS (reduced file name lengths etc), my
       wish is to build a decent program, rather  than  fit  the
       program  to  an  outdated operating system. If there is a
       *good* reason to use code that is incompatible with  DOS,
       this will be done.
       Since  optimise  takes   a  while  to optimise an antenna
       (I’ve optimised one design for a week), it  is  obviously
       more sensible to build this program under a multi-tasking
       operating system, as otherwise a PC can be  tied  up  for
       days.

BUGS

       Bugs should be reported to david.kirkby@onetel.net.  Bugs
       tend actually to be fixed if they can be isolated, so  it
       is  in  your  interest  to report them in such a way that
       they can be easily reproduced.

       The program will dump core (crash) if asked to optimise a
       1ele beam, without any arguments.  This is because a 1ele
       beam has no parasitic elements and by default the program
       only changes parasitic elements.

       Some  of the options are not checked for sensible values,
       although most are now checked and report if they are  out
       of range.

       If  the  user  specifies  very large manufacturing errors
       using  the  ’-t’  and  ’-T’  options,  its  possible  for
       elements  to  overlap  or  for  element lengths to become
       negative.  This  will   cause   numerical   errors.   Any
       reasonable values will not cause this.

       On long Yagi’s (50 elements) optimise can go a bit silly.
       It can optimise say a 1296MHz Yagi to get 20 dB  at  1296
       MHz,  but  less  than 0 dB at only 1 MHz away. Needs some
       thought!

       The level of the sidelobes is not computed with the GA or
       some  other  optimisation  types.  This will be corrected
       later.

       All those I don’t know about.

AUTHORS

       Dr. David Kirkby G8WRB  (david.kirkby@onetel.net).   with
       help  with  converting  to  DOS  from  Dr.  Joe Mack NA3T
       (mack@fcrfv2.ncifcrf.gov)