Detection of concealed object by standing waves

• US 8,174,430 B1
• Filed: 08/27/2010
• Issued: 05/08/2012
• Est. Priority Date: 07/13/2007
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: DeChiaro, Louis F. Jr.
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): Barker, Matthew M
• Application Number:
  US13/068,560
• Time in Patent Office: 620 Days
• Field of Search: 342/22
• US Class Current: 342/22
• CPC Class Codes: G01S 13/887 for detection of concealed objects, e.g. contraband or weapons
• CPC Class Codes: G01V 8/005 operating with millimetre waves, e.g. measuring the black losey radiation

Abstract

A process is provided to detect an object within a defined region using standing longitudinal cavity mode waves. The process includes disposing first and second conductive lines substantially parallel to the axis, transmitting an electromagnetic signal through the first line at a set frequency, returning the transmitted signal through the second line, measuring power from a reflected signal through the first line, adjusting the set frequency based on the measured power; extracting an appropriate parameter from the reflected signal to obtain a reflected characteristic, comparing the reflected characteristic to an established characteristic that lacks the object to obtain a characteristic differential, and analyzing the characteristic differential to obtain a position of the object along the length. The first and second conductive lines have specified length and width that bound a defined region. The analyzing can be performed by Fourier transform across wave modes.

Claims

1. A method for detecting an object within a defined region having a longitudinal axis, the method comprising:

disposing first and second conductive lines substantially parallel to the axis for a specified length and separated from each other by a specified width, the length and width bounding the defined region;

connecting the first and second conductive lines with an oscillator and a shunt respectively disposed at opposite ends of the length;

transmitting an electromagnetic signal from the oscillator through the first line at a set frequency;

returning the transmitted signal through the second line;

measuring power from a reflected signal by the shunt through the first line;

adjusting the set frequency based on the measured power;

extracting an appropriate parameter from the reflected signal to obtain a reflected characteristic;

comparing the reflected characteristic to an established characteristic that lacks the object to obtain a characteristic differential; and

analyzing the characteristic differential to obtain a position of the object along the length.

2. The method according to claim 1, wherein the appropriate parameter is frequency, and comparing operation further includes determining an offset between a first frequency for the reflected signal and a second frequency for the established signal.

3. The method according to claim 1, wherein the parameter is photon density S_m and the characteristic is mode loss α

_m, being each associated with associated with the m^th longitudinal mode, the mode loss being related by;