clc
clear
Z1=input('Enter Characteristic Impedence of Tx Lines:');
Z2=input('Enter Z2:');
L=input('Enter Length of Coupler lines with respect to wavelength:');
fo=input('Enter Design Frequency in GHz::');


Za=Z1;
Zb=Z2;

f=[fo/4:fo/50:fo+fo/4];
lambda(length(f))=zeros;
lambda=0.3./f;
beta(length(f))=zeros;
beta=2*pi./lambda;
lambda1=lambda(26);

% Even Mode Analysis

for i=1:length(f)
TstubEVEN=[1 0;j*tan(beta(i)*L*lambda1/2)*Zb 1];
Tline=[cos(beta(i)*L*lambda1) j*Za*sin(beta(i)*L*lambda1);j*sin(beta(i)*L*lambda1)/Za cos(beta(i)*L*lambda1)];
Ae=TstubEVEN*Tline*TstubEVEN;

denEVEN=Ae(1,1)+Ae(1,2)+Ae(2,1)+Ae(2,2);
TOUe(i)=(Ae(1,1)+Ae(1,2)-Ae(2,1)-Ae(2,2))/denEVEN; Txe(i)=2/denEVEN;
end

% Odd Mode Analysis
for i=1:length(f)
TstubODD=[1 0;1/(j*tan(beta(i)*L*lambda1/2)*Zb) 1];
Tline=[cos(beta(i)*L*lambda1) j*Za*sin(beta(i)*L*lambda1);j*sin(beta(i)*L*lambda1)/Za cos(beta(i)*L*lambda1)];
Ao=TstubODD*Tline*TstubODD;

denODD=Ao(1,1)+Ao(1,2)+Ao(2,1)+Ao(2,2);
TOUo(i)=(Ao(1,1)+Ao(1,2)-Ao(2,1)-Ao(2,2))/denODD; Txo(i)=2/denODD;
end

%CALCULATING S PARAMETERS

S11=0.5*TOUe+0.5*TOUo;
S12=0.5*Txe+0.5*Txo;
S14=0.5*TOUe-0.5*TOUo;
S13=0.5*Txe-0.5*Txo;


plot(f,10*log(abs(S11)),'-c');
axis([0.5 2.5 -40 0])
title('Plot of S parameters Vs. Frequency');
ylabel('|Sij|');
xlabel('frequency--------------->');
hold;
plot(f,10*log(abs(S12)),'-g');
plot(f,10*log(abs(S13)),'-r');
plot(f,10*log(abs(S14)));
figure;
plot(f,180*(angle(S11))/pi,'-c');
title('Plot of S parameters Phase Response Vs. Frequency');
ylabel('arg|Sij|');
xlabel('frequency--------------->');
hold;
plot(f,180*(angle(S12))/pi,'-g');
plot(f,180*(angle(S13))/pi,'-r');
plot(f,180*(angle(S14))/pi);