  In this paper, we consider a problem for finding the locations of
electromagnetic inhomogeneities completely embedded in homogeneous two layered
medium. For this purpose, we present a filter function operated at several
frequencies and design an algorithm for finding the locations of such
inhomogeneities. It is based on the fact that the collected Multi-Static
Response (MSR) matrix can be modeled via a rigorous asymptotic expansion
formula of the scattering amplitude due to the presence of such
inhomogeneities. In order to show the effectiveness, we compare the proposed
algorithm with traditional MUltiple SIgnal Classification (MUSIC) algorithm and
Kirchhoff migration. Various numerical results demonstrate that the proposed
algorithm is robust with respect to random noise and yields more accurate
location than the MUSIC algorithm and Kirchhoff migration.
