Simulation of radiation pattern of a large MM wave radio telescope with offset feed

The methods of radiation pattern simulation of a large MM wave radiotelescope are considered. Off/on-axis aberrations of a MM wave radio telescope are estimated. Results of single beam simulation for MM wave radio telescope RT-70 with offset feed are given. BP simulation of MM wave radiotelescope RT-70 confirms the acceptability of the off-axis aberrations with feed offset up to 100-200 lambda. Results of RT-70 radio telescope optics optimization and ray tracing are presented.