Sci-Wcalc: microstrip

Sci-Wcalc: microstrip_syn

microstrip_syn - Single microstrip transmission line synthesis

SYNOPSIS

[w_out, h_out, l_out, er_out] = microstrip_syn(z0, w, h, l, tmet, rho, rough, er, tand, f, flag)

PARAMETERS

INPUT PARAMETERS

z0 : desired characteristic impedance (Ohms)
w : width of microstrip line (meters)
h : substrate thickness (meters)
l : lentgh of microstrip line (meters)
tmet : metal thickness (meters)
rho : resistivity of the metalization (relative to copper)
rough : conductor surface roughness (meters-rms)
er : substrate relative permitivitty
tand : substrate loss tangent
f : synthesis frequency (Hz)
flag : indicates which parameters should be optimized
- flag=1 : synthesize the metal width
- flag=1 : synthesize the substrate thickness
- flag=2 : synthesize the substrate dielectric constant
- flag=3 : synthesize the metal length

OUTPUT VALUES

w_out : Calculated width of microstrip line (meters)
h_out : Calculated height of microstrip line (meters)
l_out : Calculated length of microstrip line (meters)
er_out : Calculated substrate relative permitivitty of microstrip line

DESCRIPTION

Function to synthesize the physical dimenstions of a single microstrip transmission line to achieve a desired characteristic impedance and electrical length. The desired characteristic impedance and some of the physical dimensions of the microstrip line are given as inputs and the remaining dimensions are calculated.


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

EXAMPLE

 // mils to meters conversion factor
sf=25.4e-6;
 // desired impedance
z0=75;
 // desired electrical length (degrees)
elen=90;
 // width (we'll synthesize this)
w=0;
 // height
h=62*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;
 // synthesize width
flag=0;
[w_out,h_out,l_out,er_out] = ...
  microstrip_syn(z0,elen,w,h,l,tmet,rho,rough,er,tand,f,flag);
disp(sprintf('w=%g mils, l=%g mils',w_out/sf,l_out/sf));
disp(sprintf('er=%g',er_out));
disp(sprintf('z0=%g ohms, length=%g degrees',z0,elen));