Detection of conductive material in a thin film

• US 9,383,439 B2
• Filed: 06/27/2014
• Issued: 07/05/2016
• Est. Priority Date: 06/27/2013
• Status: Active Grant

• Current Assignee: Federal Bureau of Investigation United States of America
• Original Assignee: Federal Bureau of Investigation (United States Department of Justice)
• Inventors: Buxton, Carey G, Huggins, John Scott
• Primary Examiner(s): Nguyen, Vinh
• Application Number:
  US14/317,414
• Publication Number:
  US 20150002172A1
• Time in Patent Office: 739 Days
• US Class Current: 1/1
• CPC Class Codes: G01S 13/04 Systems determining presence of a target based on relative movement of target G01S13/56
• CPC Class Codes: G01V 3/12 operating with electromagnetic waves operating with millimetre waves G01V8/005

Abstract

Provided are products used to detect and methods for detecting conductive materials in the presence of non-conductive materials, including non-conductive materials having dielectric properties. Specifically, the product is a conductive thin film detector, which is, preferably, a hand-held device designed to detect the presence of metal in, on, or under an object. This detection occurs even in the presence of non-conductive materials and other nearby conductive materials on objects that are not being tested. The device preferably includes: a power source, such as a battery; a method for activation, such as a press button; the necessary components to send and receive a radio frequency, e.g., a radio frequency generator, an antenna, and a radio frequency detector; and an indicator, such as a light or a meter, to, for example, indicate the strength of the radio frequency signal received.

Claims

1. A method of detecting whether conductive material is present in a thin film, comprising:

a. generating a single radio frequency using a transmitter;

b. guiding the generated radio frequency signal to a wideband antenna port;

c. transmitting the radio frequency signal using the wideband antenna to transmit the signal;

d. guiding the radio frequency signal flowing from the wideband antenna to a radio frequency detector;

e. converting the radio frequency signal to a viewable signal strength indicator; and

f. determining, based on the output from the signal strength indicator, whether the thin film is a conductive thin film,

wherein the thin film is in the vicinity of non-conductive dielectric material and wherein the non-conductive dielectric material generates negligible change in the performance of the wideband antenna such that the presence of conductive material can be detected.

2. The method of detecting as claimed in claim 1, wherein the generated radio frequency signal is guided to the wideband antenna port through a radio frequency circulator.

3. The method of detecting as claimed in claim 1, wherein the radio frequency signal flowing from the wideband antenna is guided to the radio frequency detector through a radio frequency circulator.

4. The method of detecting as claimed in claim 1, wherein the signal strength indicator is a light emitting diode.

5. The method of detecting as claimed in claim 1, wherein the signal strength indicator is the movement of a meter that measures signal strength.

6. The method of detecting as claimed in claim 5, wherein the radio frequency detector is in series with a comparator for detection of signal strength above a set threshold.

7. A method for detecting the presence of conductive material in the vicinity of non-conductive dielectric material, comprising:

a. employing a system, comprising;

a single source of radio frequency energy coupled to a radio frequency directional router coupled to a wideband antenna;

a radio frequency detector; and

a signal detection indicator;

b. generating a single radio frequency signal from the single source of radio frequency energy;

c. guiding the radio frequency signal generated from the single source through the radio frequency directional router to a wideband antenna;

d. radiating the radio frequency signal from the wideband antenna, wherein the wideband antenna is of sufficient bandwidth such that the non-conductive dielectric material generates negligible change in the performance of the wideband antenna;

e. guiding the radio frequency signal reflected from the wideband antenna to the radio frequency detector through the radio frequency directional router;

f. converting the radio frequency signal from the radio frequency detector to a signal strength viewable through the signal detection indicator; and

g. assessing, based on the indicator, whether conductive material is present.

8. The method for detecting as claimed in claim 7, wherein the wideband antenna is a flared monopole or dipole antenna and has a frequency range of about 900 MHz to about 3000 MHz.

9. A device for sensing the presence of a conductive thin film, comprising:

a power source, an actuator switch, a radio frequency oscillator, a radio frequency amplifier, a radio frequency circulator having a first clockwise port and a second clockwise port, a wideband antenna, a termination load, a radio frequency detector, and a detection indicator;

wherein the power source is in series with the actuator switch;

wherein the actuator switch is in series with the radio frequency oscillator and in series with the radio frequency amplifier;

wherein the radio frequency amplifier is in series with the radio frequency circulator;

wherein the first clockwise port of the radio frequency circulator is in series with the wideband antenna and the second clockwise port of the radio frequency circulator is in series with the termination load;

wherein the termination load is in series with the radio frequency detector; and

wherein the radio frequency detector is in series with the detection indicator; and

wherein the wideband antenna provides the device with immunity to dielectric loading from non-conductive material in the vicinity of conductive thin film.

10. The device of claim 9, wherein the radio frequency detector comprises an integrated circuit assembly.

11. The device of claim 9, wherein the detection indicator detects the presence of conductive material.

12. The device of claim 9, wherein the detection indicator is a light emitting diode or a meter movement.