  Focusing and resonance properties of two-dimensional small-size hemielliptic
lenses made of different materials are studied numerically in order to estimate
the influence of internal reflections on the radiation characteristics of
dielectric lens antennas. Accuracy of in-house made algorithms based on
combination of geometrical and physical optics and FDTD in the analysis of
optical and modal effects in the behavior of such lenses is tested by
comparison with the exact solution obtained using the Muller boundary integral
equations. The range of applicability for the approaches is discussed.
