function [ratio, width]=width_feedline(Zc, Er, h);

% This MATLAB file was created by Gazi K Asadullah
% Equation by Wheeler and Hammerstad
% w=width
% d=thickness
% Er= Relative permittivity
% the formula I have used here have been taken from the book called:
% Microstrip filters for RF/microwave applications, Jia-Sheng G. Hong, M.J. Lancaster
% http://www.rfdh.com/rfdb/msline.htm
% % Microwave Engineering - Third edition- David Pozar
% Microwave filters, Impedence-matching, Networks, and Coupling structures - Mathaei Young Jones
% Passive and Active filters- Theory and implementations - Wai-kai-Chen.
% Digital Signal Processing using MATLAB- Vinay K Ingle.
% Stripline Circuit design- Harlan Howe
% Approximate expressions for W/h in terms of Zc and Er derived by Wheeler and Hammerstad
% Reference: Microstriplines


Er1=(Er+1);
Er2=(Er-1);
Er12=(Er2/Er1);
A=(Zc/60);
B=(A*((Er1/2)^0.5));
C=(B + (Er12*(0.23 + (0.11/Er))));

K= (8 * (exp(C)));
M= ((exp(2*C)) - 2);

ratio = (K/M);



 if ratio >= 2 
    T=(60*(pi^2))/(Zc*sqrt(Er));
    F=(Er2/(2*Er))*(log(T-1) + 0.39 - (0.61/Er));
    ratio = ((2/pi)*((T-1) - (log((2*T)-1)) + F));
 end

width=ratio*h;