Swept Frequency Microwave Object Dimension Detection
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Solution Overview
Problem
Conventional metal detector systems at airports and security checkpoints are unable to accurately determine the dimensions of objects, making it difficult to distinguish between harmless and potentially dangerous items, such as belt buckles and handguns, and struggle with angular resolution and background interference, especially when detecting concealed weapons or explosives.
Innovation Solution
A system utilizing directional microwave and millimeter wave radiation with a controller that sweeps frequencies, performs Fourier transforms, and uses neural networks to analyze signals for dimension detection, incorporating techniques like swept reflectrometry, barrel tone detection, cross-polarization, and late time responses to identify metallic or dielectric objects, including guns and explosives, without relying on imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional detectors are used at airports, then detection of objects is achieved, but the ability to determine dimensions and distinguish between harmless and dangerous objects is insufficient
Solution Approach 1:
The patent changes the operating parameters by using swept frequency microwave radiation across a wide bandwidth (e.g., 6-18 GHz) instead of fixed frequency. This frequency sweeping enables measurement of time-domain responses that contain dimensional information about the object, resolving the contradiction between detection capability and measurement precision.
Solution Approach 2:
The patent transforms the detection approach from spatial imaging to time-domain analysis by measuring the temporal response of scattered microwave signals. This dimensionality change from spatial to temporal domain enables dimension measurement without requiring complex imaging systems, thereby improving measurement precision while avoiding information loss.
2Length of stationary object
If low frequency microwave radiation is used, then detection range is improved, but angular resolution and ability to single out particular targets deteriorates
Solution Approach 1:
The patent uses frequency sweeping across a wide bandwidth to compensate for the limited angular resolution at low frequencies. By analyzing the time-domain response characteristics at multiple frequencies, the system can achieve both long detection range and sufficient target identification capability without requiring high-frequency operation.
Solution Approach 2:
The patent employs periodic frequency sweeping to illuminate the target with microwaves at different frequencies sequentially. This periodic variation in frequency allows the system to accumulate dimensional and identification information over time, achieving both long range detection and adequate angular resolution through temporal integration.
3Area of stationary object
If wide field of view is used to detect multiple targets, then coverage area is improved, but ability to determine on which part of the target the threat is situated deteriorates
Solution Approach 1:
The patent resolves this contradiction by switching from spatial resolution to temporal resolution. The time-domain analysis of scattered signals provides depth and dimensional information about specific threat locations on the target body, enabling precise threat localization even with a wide field of view, without requiring narrow beam focusing.
4Productivity
If active microwave illumination is used, then detection speed is improved, but strong reflections from benign objects such as the human body make it difficult to distinguish from metal threat objects
Solution Approach 1:
The patent changes the analysis parameter from signal amplitude to time-domain response characteristics. By examining the temporal structure of the scattered signals, particularly the late-time responses that contain dimensional information, the system can distinguish metal threat objects from benign objects like the human body based on their different scattering signatures, maintaining fast detection speed while improving discrimination.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective remote detection and measurement of object dimensions, reducing false positives and allowing for portable, cost-effective deployment in various security applications, including covert surveillance and urban environments.
Implementation Method 1
a transmission element, for directing microwave and/or mm wave radiation
Implementation Method 2
receiving radiation from an entity resulting from the transmitted radiation
Implementation Method 3
perform a transform operation on the detection signal(s) to generate one or more transformed signals in the time domain or optical depth domain
Implementation Method 4
By actively illuminating an object with wide-range swept and/or stepped frequency microwave and/or millimeter wave radiation, the frequency response of the return signal may give the range and/or information regarding dimensions of the object
Data Source
AI summary
Provided are methods of using electromagnetic waves for detecting metal and/or dielectric objects. Methods include directing microwave and/or mm wave radiation in a predetermined direction using a transmission apparatus, including a transmission element; receiving radiation from an entity resulting from the transmitted radiation using a detection apparatus; and generating one or more detection signals in the frequency domain using the detection apparatus. Methods may include operating a controller, wherein operating the controller includes causing the transmitted radiation to be swept over a predetermined range of frequencies, performing a transform operation on the detection signal(s) to generate one or more transformed signals in the time domain, and determining, from one or more features of the transformed signal, one or more dimensions of a metallic or dielectric object upon which the transmitted radiation is incident.