How to define a circular aperture of the antenna.

Hi, I need to calculate a radiation pattern of the circular antenna with a radius of 5λ. For simplicity lets λ=1. For my mission I need to define a radius of the antenna, an azimuth angle (phi) and the cartesian coordinates. of the antenna (x,y) . I'm not sure what is the correct way to do it.

Like this:

a=5; % radius of the antenna
rho=linspace(0,a,10);
phi=linspace(0,2*pi,10);

[Rho,Phi]=meshgrid(rho,phi);
[X,Y] = pol2cart(Phi,Rho);

Or maybe like this?

a=5; % radius of the antenna
rho=linspace(0,a,10);
phi=linspace(0,2*pi,10);

x=rho.*cos(phi);
y=rho.*sin(phi);

[X1,Y1]=meshgrid(x,y);
[Rho,Phi]=meshgrid(rho,phi);