microass1.m

Designing the maximally flat quarter - wave transformer response using Binomial transformer

% Abhishek (991201), Sumit (991232)

% Designing the maximally flat quarter - wave transformer response using Binomial transformer

% Taking input of Characteristic Impedence
Z0 = input('Please give Zo of Tx line in ohms: ');
% Taking input of Real Load Impedence
ZL = input('Please give ZL of load in ohms: ');
% Taking input of Maximum Permissible VSWR
SWR =  input('Maximum Permissible Voltage Standing Wave Ratio: ');
% Taking Input of Fractional Bandwidth
BW = input('Enter Fractional Bandwidth: ');

Theta_max = pi*(2-BW)/4;   % Maximum value of Theta corresponding to Maximum Tolerable Ref. Coeff
Ref_max = (SWR-1)/(SWR+1);
Ref_Load = abs((ZL-Z0)/(ZL+Z0));

if Ref_Load ==0 
    disp('TX LINES ARE MATCHED');
    break;
end

% Calculating Minimum Number of Sections required for Matching
N = log10(abs(Ref_max/Ref_Load))/log10(abs(cos(Theta_max)));

N=ceil(N);

Impedence = zeros(1,N+1);
Impedence(1) = Z0;

% Calculating impedences of different sections
for n=1:N
    c = factorial(N)/(factorial(n-1)*factorial(N-n+1));
    Ref_Sec_Pre = (2^-N)*c*log(ZL/Z0);
    Impedence(n+1) = Impedence(n)*exp(Ref_Sec_Pre);
end

% Displaying Impedences of different sections
Impedence= Impedence(2:length(Impedence));
disp(['Zo of different sections are: ' num2str(Impedence)]);

% Initializing Normalized Frequency
f=[0:1/20:2];
VSWR = zeros(1,length(f));

% Calculating Varying VSWR and varying Reflection Coefficients value with respect to Operating Frequency
for i=1:length(f)              
    Theta = pi/2*(f(i));
    Ref_Coeff(i) = abs(Ref_Load*(cos(Theta)^N));
    VSWR(i) = (1+Ref_Coeff(i))/(1-Ref_Coeff(i));
end

plot(f,VSWR);
title('VSWR vs. Normalized Frequency');
xlabel('f/fo --->');
ylabel('VSWR --->');
figure;

plot(f,Ref_Coeff);
title('Reflection Coefficient Magnitude Vs. normalized frequency');
xlabel('f/fo --->');
ylabel('Ref Coefficient --->');