  A direct sampling method (DSM) is designed herein for a real-time detection
of small anomalies from scattering parameters measured by a small number of
dipole antennas. Applicability of the DSM is theoretically demonstrated by
proving that its indicator function can be represented in terms of an infinite
series of Bessel functions of integer order and the antenna locations.
Experiments using real-data then demonstrate both the effectiveness and
limitations of this method.
