In general

the analysis methods of paraboloidal reflector antenna use geometrical-optics and physical-optics.The preferable numerical results will be obtained by using these two methods for electrically large paraboloidal reflector antenna.For electrically small radiator

the numerical results are not in agreement with experimental results

because the feed pattern are not only determined by feed radiator but also feed structures.In this paper

the finite-difference time-domain method (FDTD) is used to analyze the feed of paraboloidal reflector antenna

and because the computing areas include all the feed structure

we can obtain the precise near fields of the feed.The currents on the paraboloidal reflector can be calculated by using equivalence principle

and then we can calculate far fields of paraboloidal reflector antenna using physical optics.Using this hybrid method

the millimeter wave paraboloidal reflector antenna with waveguide slot feed is analyzed in this paper.Numerical results are compared with the experimental results

and the comparison shows excellent agreement over a wide angle.