s4.m

smith圆图

for r=0:0.2:3;
    x=-1:0.001:1

y1=sqrt((1/(r+1)^2)-(x-r/(r+1)).^2);
y2=-sqrt((1/(r+1)^2)-(x-r/(r+1)).^2);

plot(x,y1,'r',x,y2,'r');
hold on;
end

for rr=0.1:0.2:3;
    x=(1-1./rr):0.001:1;
    
y1=sqrt(1/rr.^2-(x-1).^2)+1./rr;
y2=-sqrt(1/rr.^2-(x-1).^2)+1./rr;
y3=-(sqrt(1/rr.^2-(x-1).^2)+1./rr);
y4=-(-sqrt(1/rr.^2-(x-1).^2)+1./rr);

plot(x,y1,'b');
plot(x,y2,'b');
plot(x,y3,'b');
plot(x,y4,'b');
axis([-1,1,-1,1]);axis square;
end
hold on;