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# microstrip_Z0.lsf
#
# Microstrip characteristic impedance calculated
# from Pozar equation 3.196
#
# Copyright 2016 Lumerical Solutions Inc
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# input variables
eps_r = 2.08327^2; # relative permittivity of substrate
W = 420e-6; # strip width
d = 500e-6; # substrate thickness

# calculate effective dielectric constant of microstrip line (equation 3.195)
eps_e = (eps_r+1)/2+(eps_r-1)/2*1/sqrt(1+12*d/W);

# Calculate characteristic impedance
if((W/d) <= 1){
    Z0 = 60/sqrt(eps_e)*log(8*d/W+W/(4*d));
} else {
    Z0 = 120*pi/(sqrt(eps_e)*(W/d+1.393+0.667*log(W/d+1.444)));
}

?Z0; # print calculated characteristic impedance to script prompt