Octave-Wcalc: coax

Octave-Wcalc: coax_calc

coax_calc - Coaxial transmission line analysis

SYNOPSIS

[L, R, C, G, lc, ld, fc, em] = coax_calc(a, b, c, t, rho_a, rho_b, er, tand, len, f)

PARAMETERS

INPUT PARAMETERS

a : radius of inner conductor (meters)
b : inner radius of outer conductor (meters)
c : offset of the inner conductor from the center (meters)
t : thickness of shield (meters)
rho_a : resistivity of inner conductor (ohms/meter)
rho_b : resistivity of outer conductor (ohms/meter)
er : relative permitivitty of dielectric
tand : loss tangent of dielectric
len : physical length of line (meters)
f : analysis frequency (Hertz)

OUTPUT VALUES

L : calculated inductance per length (Henries/meter)
R : calculated resistance per length (Ohms/meter)
C : calculated capacitance per length (Farads/meter)
G : calculated conductance per length (Siemens/meter)
lc : conductor loss (dB/meter)
ld : dielectric loss (dB/meter)
fc : TE10 cutoff frequency (Hz)
em : Max Electric Field (Volts/meter)

DESCRIPTION

Function to analyze the electrical characteristics of a coaxial transmission line. The physical dimensions of the line are given as inputs and the characteristic impedance and incremental circuit model elements are calculated.

EXAMPLE

 % mils to meters conversion factor
sf=25.4e-6;
 % radius of inner conductor
a=10.0*sf;
 % inner radius of outer conductor
b=100.0*sf;
 % offset of inner conductor
c=0*sf;
 % thickness of outer conductor
t=5.0*sf;
 % resistivity of inner conductor
rho_a=3.5e-8;
 % resistivity of outer conductor
rho_b=rho_a;
 % relative permitivitty of dielectric
er=9.5;
 % dielectric loss tangent
tand=0.01;
 % length of line
len=1.0;
 % 100 MHz operation
f=100e6;
[z0,elen,loss,L,R,C,G,lc,ld,fc,em] = coax_calc(a,b,c,t,rho_a,rho_b,er,tand,len,f);
disp(sprintf('z0   = %g Ohms',z0));
disp(sprintf('elen = %g degrees',elen));
disp(sprintf('loss = %g dB',loss));
disp(sprintf('L    = %g H/m',L));
disp(sprintf('R    = %g Ohms/m',R));
disp(sprintf('C    = %g F/m',C));
disp(sprintf('G    = %g S/m',G));
disp(sprintf('Conductor loss  = %g dB/m', lc));
disp(sprintf('Dielectric loss = %g dB/m', ld));
disp(sprintf('TE10 cutoff     = %g GHz', fc/1e9));
disp(sprintf('Max E field     = %g kV/m', em/1e3));