radiation pattern of square loop Antenna

I need a help in Writing a Matlab code that analyzes a square loop antenna with half-wavelength side and fed at the mid-point of one of the sides. Sinusoidal current distribution is assumed.
Code Output:
Radiation pattern in the loop plane (the XY plane).
Radiation pattern in any plane phi=constant
The radiation resistance

Do you know the equation for the pattern?

it is a square loop in centered in the original
for the positive Y
Ay=sin(k.*(l-abs(y))).*exp(1j.*k.*sqrt(y.^2+l.^2).*sin(theta).* cos(phi-atan(y/l)));
for the negative Y
Ay=-sin(k.*(l-abs(y))).*exp(1j.*k.*sqrt(y.^2+(l.^2)).*sin(theta) .*cos(phi-atan(y/l)));
positive X
Ax=sin(k.*(l-abs(x))).*exp(1j.*k.*sqrt(x.^2+(l.^2)).*sin(theta) .*cos(phi-atan(l./x)));
negative X
Ax=-sin(k.*(l-abs(x))).*exp(1j.*k.*sqrt(x.^2+(l.^2)).*sin(theta) .*cos(phi-atan(l./x)));