[a,b,c,d]=splitoo(f,z1);

function [a,b,c,d]=splitoo(f,z1);
l1=4e-5;
%l1=2e-6;
l2=1e-7;
%l2=5e-7;
k1=0.9997;
k2=0.9997;
a=0.707;
r=220;
%z1=75;
C=4.5e-12;
lf=length(f);
W=2*pi*f';
zm=a^2*z1;
a1=zm+j*W*l2;
b1=j*W*l2*(1+k2).*(j*W*l2*(1-k2)+2*zm);
c1=ones(lf,1);
d1=zm+j*W*l2;
a=b1+a1*r;
b=r*b1;
c=C*(r+b1)-(1-a1).^2;
d=b1+a1*r;
delt=r+b1;
a=a./delt;
b=b./delt;
c=c./delt;
d=d./delt;