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| clc
syms R
C=5e-14;L=1.5e-10;Lc=3e-10;Cg=5e-14;Z1=50;Z2=50;
f=50e9;
w=2*pi*f;
Zp=2*1i*Lc*w + (R+1i*w*(L-R^2*C-L^2*C*w^2))/(1+C*((w^2*(R^2*C-2*L)+L^2*C*w^4)));
Yg=1i*Cg*w;
A=1+Yg*Zp;
CC=Yg*(Yg*Zp+2);
%D=A;
DEN=A*Z2+Zp+CC*Z1*Z2+A*Z1;
S11=(A*Z2+Zp-CC*Z1*Z2-A*Z1)/DEN;
Zv=84;
Zeq=abs((2*Z1*S11)/(1-S11));
PR=real((2*Z1*S11)/(1-S11));% Partie réelle
PI=imag((2*Z1*S11)/(1-S11));% Parie imaginaire
M=sqrt(PR^2+PI^2);
S1=solve(M-Zv,R,[0,100])
% Tracé
R=0:0.1:80;
F=eval(Zeq-84);
plot(R,F)
grid
% Calcul par polynôme
P= polyfit(R,F,3);
hold on
plot(R,polyval(P,R),'.r')
RS=roots(P) |
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