


FIRST(1)                 USER COMMANDS                   FIRST(1)



NAME
     first - YagiUda project quick antenna builder

SYNOPSIS
     first [  - hsm  ]  [  - RReflector  ]  [  - DDriven  ]  [  -
      FFirstDirector  ] [ - LLastDirector ] [ - rreflector-driven
     ] [ - ffirst-driven ] [ - ddirector-director ] [ - aangle  ]
     [ - kfiddle_factor ] filename  elements f_min f_design f_max
     f_step diameter

DESCRIPTION
     The program first 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 YagiUda antennas. first is used to define an
     antenna quickly, if you are not interested  in  analysing  a
     specific design (in which case use input ) but need to get a
     design that is half-way reasonable so that it may be  optim-
     ised.  It  is much faster in use (since its not interactive)
     than input The default is for  a  reflector,  which  is  the
     longest  element, a driven element, then 0 or more directors
     which are linearly tapered in length. This means the longest
     is  next  to  the  driven element, then they all get proges-
     sively shorter.

     The design at present that first uses if for a 20ele 432 MHz
     beam  published  in  the  ARRL  manual, 1991. It then has an
     attempt at scaling, taking into account the K factor of  the
     new design. Sometimes the design works better at a higher or
     lower frequency than desired, it which case it can  be  fid-
     dled with the option -k.

OPTIONS
     -h   Print a help message.

     -s   Show the default values of all the configurable parame-
          ters  to stdout, then exit. Typing this option with any
          option  that  changes  a  parameter  (see  below)  will
          display the new value of the parameter, rather than the
          default.

     -m   When this is invlked, the program does  not  allow  for
          the  different  diameter elements. By default, it tries
          to allow for the fact that the elements dont  have  the
          same  K  factor  as  the design on which the program is
          based.

     -RReflector
          Reflector  is  the   length   of   the   reflector   in
          wavelengths. Typically this might be 0.4896

     -DDriven



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          The length of the  driven  element  in  wavelengths  is
          Driven Typically this might be 0.481

     -FFirstDirector
          The length of the First director in wavelengths.  Typi-
          cally this might be 0.4536.

     -LLastDirector
          The length of the Last director in  wavelengths.  Typi-
          cally this might be 0.3758.

     -rreflector-driven
          This is the spacing in wavelengths between the  reflec-
          tor and driven element. Typically this might be 0.1498.
          Reducing this gives a  higher  gain  antenna,  but  the
          input impedance can become impractically low.

     -ffirst-driven
          This is the spacing in wavelengths between  the  driven
          element  and  the first director. Typically it might be
          0.06048.

     -ddirector-director
          This is the spacing in wavelengths  between  directors.
          Typically this might be 0.350.

     -aangle
          angle is the step size in degrees for which the angular
          dependance  of gain is calculated by output The default
          is 180 degrees, which makes calculation fast.

     -kfiddle_factor
          The  lengths  of  all   elements   are   increased   by
          fiddle_factor. This is used if the origianl design form
          first is too high or low in frequency. If the  original
          design   seems   better   at  higher  frequencies  than
          required, run again with k > 1, to increase the  length
          of all elements.

      filename
          is the name of the file in which to place  the  antenna
          description.  It  is  in  a  format that can be read by
          either yagi or optimise - two  other  programs  in  the
          YagiUda  project.  It  is an ASCII text file, so can be
          read by humans and edited with a text editor.

      elements
          This is the number of elements for the  Yagi  to  have.
          All  Yagis  created  by  first  have one reflector, one
          driven element and zero or more directors.

      f_min



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FIRST(1)                 USER COMMANDS                   FIRST(1)



          This is the minimum  frequency  that  the  Yagi  to  be
          described  in  filename  will  be  used at. It sets the
          lower limit of frequency for which yagi will  calculate
          data.

      f_design
          This is the  design  frequency  that  the  Yagi  to  be
          described  in filename will be used at. It is currently
          the only frequency at  which  optimise  will  calculate
          data.

      f_max
          This is the maximum  frequency  that  the  Yagi  to  be
          described  in  filename  will  be  used at. It sets the
          upper limit of frequency for which yagi will  calculate
          data.

      f_step
          This is the frequency steps that the performance of the
          Yagi  to be described in filename will be calculated at
          by yagi and output It it not currently used at  all  by
          optimise

      diameter
          This is the diameter of the elements in  mm.  All  ele-
          ments are of the same diametr and are not tapered.



LIMITATIONS
     Filenames, including full path, can't exceed 90 characters.

     Does not take into account the varaition of impedance  of  a
     dipole with change in wavelength/diamter of elements.

FILES
     filename          Yagi description, created by first.
     filename.out      Binary data file, created by yagi.
     filename.dat      Perfomance of antenna, created by output.
     filename.gai      Gain of antenna, created by output.

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

COPYING
     This program is public domain,  but 4 of the source routines
     are copyrighted.  In order to build, you will need to obtain
     the routines cisi.c, complex.c, lubksb.c and  ludcmp.c  from
     the  book 'Numerical Recipes in C', 2nd edition, by Press et
     al, Cambridge University Press, (1992).



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     You may copy the sources (less those 4) and  executables  to
     anyone  you wish in the usual unix tradition, as long as you
     let people know they can get the sources and dont  make  any
     profit from it. You may charge a *small* distribution fee.


AUTHORS
     Dave Kirkby G8WRB (davek@medphys.ucl.ac.uk).  with help with
     the  conversion  to the DOS/PC enviroment from Joe Mack NA3T
     (mack@fcrfv2.ncifcrf.gov)

SEE ALSO
     input(1), output(1), yagi(1), optimise(1).

BUGS
     Bugs   should   be   reported   to:   David   Kirkby   G8WRB
     (davek@medphys.ucl.ac.uk).   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.

     If the input file is edited manually and  done  incorrectly,
     there can be unpredictable results.

     Options are not checked for  sensible  numbers.  A  negative
     length can be entered!






























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