how to check beamwidth

Hello all,
I simulated circular polarized circular microstrip antenna in IE3D.
I am attaching .geo file can anybody tell how to measure beamwidth? Simulation frequency band- 2.25 GHz to 2.65 GHz
I am selecting Φ=0 and θ varying from 0 to 180....I am doing right?

I assume your antenna has main lobe in vertical (Z) direction. Use the 2D display option. you should select "elevation radiation pattern".

Use sufficient theta angles to get a smooth pattern. select phi = 0 (for pattern in the XZ plane) and phi = 90 (for pattern in YZ plane). Also select the requried circular polarization.

I hope this solves your display problem.

Thank you, it realy helped me.