What about the antenna do you want to simulate? Most circular polarizations are made with a horizontal and a vertical antenna fed 90 degrees apart. If this is your case you can take advantage of orthogonality and simulate each antenna separately and add the electric fields at any azimuth, elevation, and range. Or you can do the whole works at once.
SuperNEC is good but it requires matLAB.
There are several free NEC programs here
https://www.qsl.net/wb6tpu/swindex.html