Sci-Wcalc: coupled_microstrip

Sci-Wcalc: coupled_microstrip_calc

coupled_microstrip_calc - Coupled microstrip transmission line analysis

SYNOPSIS

[z0, k, z0e, z0o, kev, kev, loss, deltal] = coupled_microstrip_calc(w, s, h, l, tmet, rho, rough, er, tand, f)

PARAMETERS

INPUT PARAMETERS

w : width of coupled microstrip lines (meters)
s : spacing between coupled microstrip lines (meters)
h : substrate thickness (meters)
l : lentgh of coupled microstrip line (meters)
tmet : metal thickness (meters)
rho : resistivity of the metal (ohm-meters)
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)
k : calculated coupling coefficient
z0e : calculated even mode characteristic impedance (Ohms)
z0o : calculated odd mode characteristic impedance (Ohms)
kev : calculated even mode effective relative permitivitty
kev : calculated odd mode effective relative permitivitty
loss : calculated loss of the line (dB)
deltal : calculated open circuit end correction (meters)

DESCRIPTION

Function to analyze the electrical characteristics of a coupled microstrip transmission line. The physical dimensions of the coupled 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-->|<-S->|<--W-->|
               _______       -------
              | metal |     | metal | <- rho,rough
    ----------------------------------------------
   (  dielectric                         /|\     (
    )   er,tand                       H   |       )
   (                                     \|/     (
    ----------------------------------------------
    XXXXXXXXXXXXXXXXXX ground XXXXXXXXXXXXXXXXXXXX

EXAMPLE

 // mils to meters conversion factor
sf=25.4e-6;
 // width 
w=20*sf;
 // spacing
s=8*sf;
 // height
h=15*sf;
 // length
l=1100*sf;
 // metal thickness
tmet=1.4*sf;
 // resitivity relative to copper
rho=1;
 // metal surface roughness
rough=0.05*sf;
 // relative dielectric constant
er=4.5;
 // loss tangent
tand=0.01;
 // frequency
f=2.4e9;
[z0,k,z0e,z0o,kev,kodd] = ...
  coupled_microstrip_calc(w,s,h,l,tmet,rho,rough,er,tand,f);
disp(sprintf('z0=%g Ohms, k=%g',z0,k));
disp(sprintf('z0e=%g Ohms, z0o=%g Ohms',z0e,z0o));
disp(sprintf('kev=%g, kodd=%g',kev,kodd));