Non-intrusive inspection impulse radar antenna

• US 7,042,385 B1
• Filed: 09/16/2003
• Issued: 05/09/2006
• Est. Priority Date: 09/16/2003
• Status: Active Grant

• Current Assignee: NIITEK, Inc.
• Original Assignee: NIITEK, Inc.
• Inventors: Wichmann, Gunter
• Primary Examiner(s): PIHULIC, DANIEL T
• Application Number:
  US10/664,047
• Time in Patent Office: 966 Days
• Field of Search: 342/22, 89/11.3
• US Class Current: 342/22
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01S 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 13/888 through wall detection
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005
• CPC Class Codes: Y10T 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49016 Antenna or wave energy "plumbing" making
• CPC Class Codes: Y10T 29/49018 with other electrical component

Abstract

An apparatus and method for detecting objects buried beneath the surface of a medium. A plurality of wide-bandwidth antennas, coupled to form an array, is drawn across the surface. Each antenna radiates a plurality of pulses of electromagnetic radiation at periodic intervals of time and receives the plurality of pulses after their interaction with the medium. The return pulses are sampled by a sampling circuit disposed at the feed of each antenna so as to create an equivalent-time pulse signal, and a self-signature of each antenna is subtracted from the equivalent-time pulse signal so as to detect features of objects buried beneath the surface of the medium. A pulse former is provided at the feedpoint of the receiving antenna.

Claims

1. A method for detecting objects buried beneath a surface of a medium, the method comprising:

a. providing a plurality of antennas coupled into an array, each antenna characterized by a feed;

b. drawing the plurality of antennas across the surface;

c. radiating a plurality of transmitted pulses of electromagnetic radiation at periodic intervals of time;

d. receiving the plurality of pulses in the array of antennas after interaction with the medium;

e. forming pulses synchronous with the transmitted pulses by means of a pulse former disposed at the feed of each antenna;

f. sampling the plurality of pulses by a sampling circuit, the sampling circuit disposed at the feed of each antenna so as to create an equivalent-time pulse signal; and

g. subtracting a self-signature of each antenna from the equivalent-time pulse signal so as to detect features of objects buried beneath the surface of the medium.

2. A method in accordance with claim 1, wherein providing a plurality of antennas includes stacking low-radar cross-section members.

3. A method in accordance with claim 2, wherein stacking low-radar cross-section members includes stacking plastic sheets.

4. A method in accordance with claim 1, wherein providing a plurality of antennas includes adhering plastic sheets to high-strength structural members.

5. A method in accordance with claim 1, wherein sampling the plurality of pulse includes disposing only the pulse former, a receiving diode, an integrating capacitor, and an impedance converter at the feed of each antenna.

6. A receiver for an impulse radar system characterized by a strobe pulse, the receiver comprising:

a. a broadband antenna having a feed;

b. a low-radar cross-section front-end module coupled directly to the feed of the antenna, the front-end module including only a receiving diode, an integrating element, and a impedance matching element;

c. an input for coupling the strobe pulse to the receiving diode;

d. a transmission line having a proximal end coupled to the front-end module and a distal end; and

e. a processor coupled to the distal end of the transmission line for analyzing signals received from the front end module.

7. A receiver in accordance with claim 6, wherein the integrating element is a capacitor.

8. A receiver in accordance with claim 6, wherein the broadband antenna is characterized by a resistivity per-unit-length, and wherein the resistivity per-unit-length increases with distance from the feed.

9. A receiver in accordance with claim 8, wherein the resistivity per-unit-length increases linearly with distance from the feed.