NEC-LIST: modeling Archimedes spiral antenna

Hello Heriberto,
 
You can model an Archimedes spiral antenna with the NEC-WIN Pro
program. But any other NEC program should also make modeling
possible.
 
The Archimedes spiral antenna typically consists of two
counter-rotating flat spirals (spiral arms), usually on a flat
substrate or dielectric base. The spiral is excited at the start of
the two spirals.
 
The NEC Code is the GH card for Helix-Spiral specification. In this
code, the radius A2 = A1 and HL = 0, for a flat spiral !
 
If you don't have this code, you may generate the spirals in many
piece-wise straight segments, according to the Archimedes spiral
geometry.
 
The Archimedes spiral antenna parameters are :
 
P.D. = a/lambda * 4 * pi^2
 
    where P.D. = phase difference
          lambda = wavelength
               a = spacing (dimensions) between the two opposite
                   spiral arms
 
Number of turns = P.D. * lambda / 4 * pi^2 * a
 
Average diameter of spiral : dia = lambda / pi
 
Hope this will help you.
 
Max Schmitt
Ant. Cons. Eng.
Received on Mon Aug 09 1999 - 07:22:00 EDT