Octave-Wcalc: microstrip

Octave-Wcalc: microstrip_calc

microstrip_calc - Symmetric microstrip transmission line analysis

SYNOPSIS

[z0, keff, elen, loss, L, R, C, G, lc, ld, deltal, depth] = microstrip_calc(w, h, l, tmet, rho, rough, er, tand, f)

PARAMETERS

INPUT PARAMETERS

w : width of microstrip line (meters)
h : substrate thickness (meters)
l : lentgh of microstrip line (meters)
tmet : metal thickness (meters)
rho : resistivity of the line (relative to copper)
rough : conductor surface roughness (meters-rms)
er : substrate relative permitivitty
tand : substrate loss tangent
f : analysis frequency (Hz)

OUTPUT VALUES

z0 : calculated characteristic impedance (Ohms)
keff : calculated effective relative permitivity
elen : calculated electrical length of the line (degrees)
loss : calculated loss of the line (dB)
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)
deltal : calculated open circuit end correction (meters)
depth : calculated skin depth (meters)

DESCRIPTION

Function to analyze the electrical characteristics of a single microstrip transmission line. The physical dimensions of the microstrip line are given as inputs and the characteristic impedance, effective dielectric constant, loss and open circuit end correction are calculated. The model accounts for dispersion (frequency dependent propagation velocity).


                 |<--W-->|
                  _______    
                 | metal | <- rho,rough
    ----------------------------------------------
   (  dielectric                         /|\     (
    )   er,tand                       H   |       )
   (                                     \|/     (
    ----------------------------------------------
    XXXXXXXXXXXXXXXXXX ground XXXXXXXXXXXXXXXXXXXX

EXAMPLE

 % mils to meters conversion factor
sf=25.4e-6;
 % width
w=20*sf;
 % height
h=15*sf;
 % length
l=1100*sf;
 % metal thickness
tmet=1.4*sf;
 % resitivity
rho=1.72e-8;
 % metal surface roughness
rough=0.05*sf;
 % relative dielectric constant
er=4.5;
 % loss tangent
tand=0.01;
 % frequency
f=2.4e9;
[z0,keff,elen,loss,L,R,C,G,lc,ld,deltal,depth] = ...
  microstrip_calc(w,h,l,tmet,rho,rough,er,tand,f);
disp(sprintf('z0   = %8.4g Ohms', z0));
disp(sprintf('keff = %8.4g ', keff));
disp(sprintf('elen = %8.4g degrees', elen));
disp(sprintf('loss = %8.4g dB', loss));
disp(sprintf('L    = %8.4g H/m', L));
disp(sprintf('R    = %8.4g Ohms/m', R));
disp(sprintf('C    = %8.4g F/m', C));
disp(sprintf('G    = %8.4g S/m', G));
disp(sprintf('lc   = %8.4g dB/m', lc));
disp(sprintf('ld   = %8.4g dB/m', ld));
disp(sprintf('open end correction = %8.4g mil', deltal/sf));
disp(sprintf('skin depth = %8.4g um', depth*1e6));