A steerable electromagnetic induction (EMI) sensor system for measuring the magnetic
polarizability tensor of a metal target. Instead of creating a vertical magnetic
field from a horizontal loop transmitter configuration used by most prior art EMI
metal detectors, the transmitter geometry of the sensor system's antenna is designed
especially for creating multiple horizontal and vertical magnetic fields and for
steering the same in all directions. The horizontal magnetic field (HMF) antenna
has the potential advantage of a relatively uniform magnetic field over a large
volume. A second potential advantage of the HMF antenna is that compared to a conventional
loop antenna, the magnetic field intensity falls off slowly with distance from
the plane of the antenna. Combining two HMF sensor systems creates a steerable
two-dimensional magnetic field sensor. Combining the steerable HMF sensor with
a vertical magnetic field antenna forms a three-dimensional steerable magnetic
field sensor system.