Soft magnetic bands for tilted coil antennas
First Claim
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1. An antenna assembly, comprising:
- a tool mandrel having a longitudinal axis;
a coil including a plurality of windings wrapped about the tool mandrel and tilted to form a winding angle with respect to the longitudinal axis; and
a soft magnetic band having an edge radially interposing the coil and the tool mandrel and extending about a circumference of the tool mandrel, the edge being tilted to form a band angle with respect to the longitudinal axis and orthogonal to the winding angle about the entire circumference of the tool mandrel, wherein the soft magnetic band includes a plurality of inserts, and wherein a gap is defined between each laterally adjacent insert and the gap extends parallel to the longitudinal axis.
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Abstract
An antenna assembly includes a tool mandrel having a tool axis, and a coil including a plurality of windings wrapped about the tool mandrel at a winding angle offset from the tool axis. A soft magnetic band radially interposes the coil and the tool mandrel and extends about a circumference of the tool mandrel at a band angle orthogonal to the winding angle. The soft magnetic band includes a plurality of inserts, and a gap is defined between each laterally adjacent insert and the gap extends parallel to the tool axis.
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Citations
18 Claims
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1. An antenna assembly, comprising:
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a tool mandrel having a longitudinal axis; a coil including a plurality of windings wrapped about the tool mandrel and tilted to form a winding angle with respect to the longitudinal axis; and a soft magnetic band having an edge radially interposing the coil and the tool mandrel and extending about a circumference of the tool mandrel, the edge being tilted to form a band angle with respect to the longitudinal axis and orthogonal to the winding angle about the entire circumference of the tool mandrel, wherein the soft magnetic band includes a plurality of inserts, and wherein a gap is defined between each laterally adjacent insert and the gap extends parallel to the longitudinal axis. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method, comprising:
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introducing a wellbore logging tool into a wellbore, the wellbore logging tool including an antenna assembly that includes; a tool mandrel having a longitudinal axis; a coil including a plurality of windings wrapped about the tool mandrel and tilted to form a winding angle with respect to the longitudinal axis; and a soft magnetic band having an edge radially interposing the coil and the tool mandrel and extending about a circumference of the tool mandrel, the edge being tilted to form a band angle with respect to the longitudinal axis and orthogonal to the winding angle about the entire circumference of the tool mandrel, wherein the soft magnetic hand includes a plurality of inserts, and wherein a gap is defined between each laterally adjacent insert and the gap extends parallel to the longitudinal axis; and
obtaining measurements of a surrounding subterranean formation with the wellbore logging tool. - View Dependent Claims (9, 10)
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11. A method of assembling an antenna assembly, comprising:
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positioning a soft magnetic band, having an edge, about a circumference of a tool mandrel having a longitudinal axis, wherein the edge extends about the tool mandrel and is tilted to form a band angle with respect to the longitudinal axis, the soft magnetic band including a plurality of inserts, and wherein a gap is defined between each laterally adjacent insert and the gap extends parallel to the longitudinal axis; wrapping a plurality of coil windings about the tool mandrel at, the coil windings being tilted to form a winding angle with respect to the longitudinal axis and orthogonal to the band angle about the entire circumference of the tool mandrel, such that the soft magnetic band radially interposes at least a portion of the coil windings; and tuning the soft magnetic band to optimize a magnetic dipole moment of the antenna assembly. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification