Abstract: An antenna assembly includes a first leg extending radially over a circumference of a tool, a second leg extending axially over a length of the tool, a third leg radially over a portion of a circumference of the tool, and a fourth leg extending axially over a length of the tool.

Abstract: A logging tool having a plurality of spatially separated antennas is provided and used to make propagation-style measurements in a formation. Tensors are formed using the propagation-style measurements and one or more quantities are computed using the tensors. A formation evaluation is performed using the computed quantities. The formation evaluation determines a formation property or parameter such as horizontal resistivity, vertical resistivity, relative dip, azimuthal dip, bed boundary location, or bed thickness. The computed quantities may include compensated phase shift resistivity, compensated attenuation resistivity, symmetrized phase shift resistivity, symmetrized attenuation resistivity, anti-symmetrized phase shift resistivity, and anti-symmetrized attenuation resistivity. The measurements may be corrected for antenna gain errors and an air calibration may be performed.

Abstract: A method to obtain gain-corrected measurements. A measurement tool having one or more arrays is provided, wherein the arrays include two co-located triaxial transmitters and two co-located triaxial receivers. Measurements are obtained using the transmitters and the receivers. Impedance matrices are formed from the obtained measurements and the impedance matrices are combined to provide gain-corrected measurements. The apparatus may alternatively be a while-drilling logging tool having one or more arrays, wherein each array comprises a transmitter, a receiver, and a buck, and wherein the signal received by the receiver is subtracted from the signal received by the buck or vice versa. A slotted shield may be incorporated into either embodiment of the tool. The slots may form one or more island elements. A material is disposed in the slots. The islands and shield body have complementary tapered sides that confine the islands within the shield body.

Abstract: Various triaxial antenna designs having are provided. Some embodiments include a split-z coil that can include two axial coils with saddle coils in the x- and y-directions located therebetween. The split z-coils can function by having a combined magnetic moment similar to that of a single axial coil located between the two parts of the split z-coil. In some examples, the antenna assemblies can include a protrusion or other non-planar structure.

Abstract: Various triaxial antenna designs having are provided. Some embodiments include a split-z coil that can include two axial coils with saddle coils in the x- and y-directions located therebetween. The split z-coils can function by having a combined magnetic moment similar to that of a single axial coil located between the two parts of the split z-coil. In some examples, the antenna assemblies can include a protrusion or other non-planar structure.

Abstract: Various triaxial antenna designs having are provided. Some embodiments include a split-z coil that can include two axial coils with saddle coils in the x- and y-directions located therebetween. The split z-coils can function by having a combined magnetic moment similar to that of a single axial coil located between the two parts of the split z-coil. In some examples, the antenna assemblies can include a protrusion or other non-planar structure.

Abstract: A method to obtain gain-corrected measurements. A measurement tool having one or more arrays is provided, wherein the arrays include two co-located triaxial transmitters and two co-located triaxial receivers. Measurements are obtained using the transmitters and the receivers. Impedance matrices are formed from the obtained measurements and the impedance matrices are combined to provide gain-corrected measurements. The apparatus may alternatively be a while-drilling logging tool having one or more arrays, wherein each array comprises a transmitter, a receiver, and a buck, and wherein the signal received by the receiver is subtracted from the signal received by the buck or vice versa. A slotted shield may be incorporated into either embodiment of the tool. The slots may form one or more island elements. A material is disposed in the slots. The islands and shield body have complementary tapered sides that confine the islands within the shield body.