SYSTEM FOR RESOLVING THE SIZES AND CENTROID LOCATIONS OF BURIED OBJECTS

• US 3,775,765 A
• Filed: 12/08/1971
• Issued: 11/27/1973
• Est. Priority Date: 12/08/1971
• Status: Expired due to Term

• Current Assignee: Clifford Warren Schaible, Gerald Charles Di Piazza, Henry Oswald, Peter Onno
• Original Assignee: Clifford Warren Schaible, Gerald Charles Di Piazza, Henry Oswald, Peter Onno
• Inventors: Schaible, Clifford Warren, Di Piazza, Gerald Charles, Onno, Peter, Oswald, Henry
• Primary Examiner(s): Hubler, Malcolm F.
• Application Number:
  US05/205,937
• Time in Patent Office: 720 Days
• Field of Search: 343/5R,7A 181/.5EC
• US Class Current: 342/22
• CPC Class Codes: G01S 13/0209 Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

A broadband, radar-type system for resolving the sizes and centroid locations of objects buried at a maximum depth in the order of 6 to 10 feet is disclosed. The system uses a carrier frequency which is high enough so that an instantaneous bandwidth of about 25 percent provides resolution in the order of 1 foot. The system antenna includes impedance matching and focusing means. Polarization diversity of the transmitted beam may be accomplished to distinguish between elongated and generally round objects.

Claims

1. Apparatus for detecting an object below the surface of the earth, said apparatus comprising a transmitter for generating a pulse modulated carrier wave, a receiver, an antenna assembly movable over said surface of said earth and having an output impedance approximately equal to that of said surface, an electrically controlled impedance matching means connected to said antenna assembly, and means for alternately connecting said transmitter and said receiver to said impedance matching means, said last-mentioned means comprising feedback control means responsive to energy through said lastmentioned means to control said impedance matching means to optimize the impedance match between said antenna assembly and said mean for connecting, and delay means to cause the transmission time from said transmitter to said antenna assembly to said receiver to equal a period at least equal to the duration of said pulse modulated carrier wave produced by said transmitter.

2. Apparatus in accordance with claim 1 in which said feedback control means is further connected to said receiver to protect said receiver during periods when received signals exceed predetermined levels.

3. Apparatus in accordance with claim 1 in which said antenna assembly includes dielectric means conformable to said surface of said earth.

4. Apparatus in accordance with claim 3 in which said feedback control means is further connected to said receiver to protect said receiver during periods when received signals exceed predetermined levels.