theta = (0:80).'; %column vector
freq = 18:22; %row vector
gain_mag = sin(pi/2 .* N .* sin(theta) .* (freq/fc-1)) ./ sqrt(N) .* sin(pi/2 .* sin(theta) .* (freq/fc-1));
gain_phase = exp(1j*pi/2 .* (N-1) .* sin(theta) .* (freq/fc-1));
gain = gain_mag .* gain_phase;
surf(freq, theta, gain)
There are two tricks here:
- Use element-by-element operators such as .* because you are going to be multiplying and dividing non-scalars
- Use a row vector for one of the variables and a column vector for the other one, and starting R2015b MATLAB will automatically expand that into grids of calculations. If you are using an earlier version, you would want to use meshgrid() to make theta and freq 2D grids of values.
