inverse FFT for recreating radiation pattern

Hello,I have created a code which created the plot below. The heart of the code is the AF expression.(array factor) I want to do the inverse process , to take the plot do the inverse of it and somehow to find using optimization the coeffects(genetic algorithm) which will recreate the plot. my plot is from -90 to 90 degrees what could be done next to continue the process? Is there a manual you could reccomend?

Thanks.

theta=linspace(-pi/2,pi/2,1000);
f=5.6;

N=6;

lambda=300/f;
d=0.8*lambda;

theta_0=pi*((0)/180);
amplitude_norm_V=[0.05,0.3,0.75,1,0.75,0.3,0.05];
k=(2*pi)/lambda;
delta=k*d*cos(theta_0);
x=sqrt(1/(sum(amplitude_norm_V.^2)));
real_voltage=amplitude_norm_V.*x;
real_power=(real_voltage.^2);
sum(real_power);
phases=[0,0,0,0,0,0,0]



total=0;
tot=0;
for z=1:6
AF=real_voltage(z)*exp(1i*(phases(z)/180*pi))*exp(-1i*(z-1)*k*d*cos(theta)+1i*(z-1)*delta);
total=total+AF;

end
plot((theta/pi)*180,20*log10(total));

sin_p=cos(theta_0)+lambda/d;