# I can't control the beam direction of circular array antenna

I'm working on array antenna. When I use Rectangular, it's easy to control the beam direction because there is Scan Angle X and Y available on properties tab. But, there wasn't when I use Circular. There was only Phase Shift and I don't know how to deal with it.

I know the formula to calculate the Array Factor of circular array.

I would like to know how to control the beam direction and also what Phase Shift mean on the Array factor formula. There is theta and phi, so I got really confused with Phase Shift.

Thank you.

Phase Shift is the phase difference between two consecutive elements on the array.
For linear and rectangular arrays, there is a relationship between beam angle and phase shift (available in any textbook).
This is not the case for circular arrays, where the relationship between the phase applied to each element and the beam angle is a bit more complicated. You can for example find it in formula (18.38) of this document: http://www2.elo.utfsm.cl/~elo352/biblio/antenas/Lectura 18.pdf

@sylvain Thank you. I've misunderstood.

I checked the Array factor again and it worked well on the simulation. I was able to control the beam direction by changing the phase shift.

And here is another question. I controlled the beam direction, but it was a bit different from the theoretical result. Is this because I used the half-wave length Dipole instead of isotropic antenna?

Did I have to multiply the array factor by element directivity(in this case, Dipole) ? like sin(theta) or something. I'm talking about the theory, like calculation.

@rose, you write "it was a bit different from the theoretical result", but unfortunately I don't fully understand what you did, what you are trying to do, and what you are comparing your results to. Perhaps if you describe (with e.g. screenshots and equations) both what you did and what the "theoretical results" I can try and find why they do not match.