Passive electrical marker for underground use and method of making thereof

US6097293A · kind A · utility

Assignee

• Industrial Technology Group, LLC · US

Inventors

• George G. Galloway · Weatherford, US
• Ronald L. McWilliams · Mineral Wells, US
• John Moss · Weatherford, US
• Kenneth D. Napps · Mineral Wells, US
• Sean Nash · Rancho Santa Margarita, US
• Paul R. Siglinger · Weatherford, US
• William C. Wood · Chesterfield, US

Key dates

• Filing date: Apr 15, 1999
• Grant date: Aug 1, 2000
• Expiry date: Apr 15, 2019

Classification

• Technology area (CPC G): Physics
• CPC primary: G01V15/00
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A passive electrical marker has tuned circuits, each of which includes a coil and a capacitance. The tuned circuits are oriented with respect to each other in a predetermined arrangement so as to provide a broader spatial response. A foamed core inside of the tuned circuits maintains the tuned circuits in their respective orientations and protects the tuned circuits from mechanical shock. A shell or housing around the foamed tuned circuits provides environmental protection to the tuned circuits. The tuned circuits can be foamed together in a mold and then placed into the housing. Alternatively, the tuned circuits can be foamed together inside of a housing, which housing maintains the orientations between the tuned circuits during foaming. As still another alternative, the housing can be applied to the outside of the foamed tuned circuits as a coating.