  We use both FEM (finite element method) and FDTD (finite difference time
domain method) to simulate the field distribution in Maxwell's fish eye lens
with one or more passive drains around the image point. We use the same
Maxwell's fish eye lens structure as the one used in recent microwave
experiment [arXiv:1007.2530]: Maxwell's fish eye lens bounded by PEC (perfect
electric conductor) is inserted between two parallel PEC plates (as a waveguide
structure). Our simulation results indicate that if one uses an active coaxial
cable as the object and set an array of passive drains around the image region,
what one obtains is not an image of the object but only multiple spots
resembling the array of passive drains. The resolution of Maxwell's fish eye is
finite even with such passive drains at the image locations. We also found that
the subwavelength spot around the passive drain is due to the local field
enhancement of the metal tip of the drain rather than the fish eye medium or
the ability of the drain in extracting waves.
