inset_feed.m

patchantenna matlab code

function yo= inset_feed(length, width, fr, Zc, h)

% This function was created by Gazi K Asadullah
% This function calculates the input impedance for the antenna and calculates the position of inset feed point where the
% input impedance in 50 ohm.
% yo= distance from the edge of antenna to the feed point where the impedance is 50 ohm.
% width = width of the patch antenna
% length = length of the patch antenna
% fr = resonant frequency

fr=fr*(1e+9);
c=((2.9986e+8)*100)/2.54 ;%inch/sec
lamda_o=c/fr; %inch
ko=(2*pi)/lamda_o;

A=(1/(120*(pi^2)));

% Reference: Page : 732 (Antenna Theory: Analysis and design)
F1=0;
for theta=[0:1:180]*pi/180
    z=ko*length*sin(theta);
    J = besselj(0,z);
    I = (((sin((ko*width/2)*cos(theta)))/cos(theta))*((sin((ko*width/2)*cos(theta)))/cos(theta)))*J*((sin(theta))^3)*(pi/180);
    F1=I+F1; %current (I1=F1)
end
g12=F1*A;



F3=0;
% cacluation of G1 (conductance):
% for phi=[0:1:180]*pi/180
%     F2 = (((sin((ko*width/2)*cos(phi)))/cos(phi))*((sin((ko*width/2)*cos(phi)))/cos(phi)))*(sin(phi).^3)*(pi/180);
%     F3=F2+F3;
% end
% g1=F3*A;
% g12=6.1683e-004;
if (width > lamda_o)
    g1=(1/120)*(width/lamda_o);
end
if (width < lamda_o)
    g1=(1/90)*((width/lamda_o)^2);
end

Rin=(1/(2*(g1+g12))); %input impedance of the antenna


yo= (acos(sqrt(Zc/Rin))*length)/pi;