Patent ID: 8884624

Claim:
A downhole logging tool comprising: a tool body having a longitudinal axis; a set of antennas located on the tool body, the set of antennas comprising coil windings forming a closed-loop pattern, the coil windings forming at least co-located first and second antennas of the set of antennas, wherein the first antenna has a dipole moment substantially parallel to the longitudinal axis of the tool body and the second antenna has a dipole moment substantially perpendicular to the longitudinal axis of the tool body; and a shield disposed over the set of antennas such that it is substantially co-axial with the tool body and comprising a plurality of slots, wherein the plurality of slots comprises a first group of slots oriented substantially parallel to the longitudinal axis of the tool body and a second group of slots oriented non-parallel to the longitudinal axis of the tool body; wherein each of the slots is substantially perpendicular to a proximate portion of at least one of the underlying coil windings, and wherein a path length around each slot is more than twice the length of a distance between the slot and a directly adjacent slot along an arc of the coil windings; wherein the coil windings form a third antenna of the set of antennas, the third antenna being co-located with the first and second antennas, and wherein the third antenna has a dipole moment that is substantially perpendicular to the dipole moment of the second antenna and to the longitudinal axis of the tool body; wherein the first group of slots comprises a first set of slots and a second set of slots, wherein: the first set of slots of the first group is arranged such that each of the slots of the first set overlay the first antenna and are interposed between but do not overlay the second and third antennas; and the second set of slots of the first group is arranged such that each of the slots of the second set overlay the first antenna and one of the second or third antennas.