Multi-Static Transceiver Array for Dielectric Property Determination
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Solution Overview
Problem
Conventional systems using microwave or millimeter-wave radiation to scan objects, such as the sole of a shoe, are limited in their ability to unambiguously determine dielectric properties due to polarization independence at normal incidence, preventing the separation of depth and refractive index of layers within the object.
Innovation Solution
A system employing multiple transceivers positioned in fixed spatial relationships to generate and detect microwave or millimeter-wave radiation, calculating reflectivity coefficients and complex permittivity by analyzing the ratio of detected signals to transmitted signals, and using non-linear regression to fit electromagnetic models of the object, allowing for the determination of dielectric properties and layer thicknesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional mono-static radar systems are used to scan objects, then a three-dimensional image can be formed, but the dielectric properties cannot be unambiguously determined due to polarization independence at normal incidence
Solution Approach 1:
The patent transitions from mono-static radar to a multi-static configuration where transceivers are arranged in multiple arrays at different positions and orientations. This adds spatial and angular dimensions to the measurement system, enabling polarization-dependent measurements that were not possible with single-position normal incidence radar. The multi-static arrangement creates multiple illumination angles and polarization states, resolving the ambiguity in dielectric property determination.
Solution Approach 2:
The system divides the measurement function into multiple independent transceiver pairs, each capable of transmitting and receiving electromagnetic waves. By segmenting the system into multiple spatially separated transceiver arrays, the patent enables independent measurement of reflectivity coefficients for different polarization states, which is essential for unambiguous dielectric property extraction.
2Measurement precision
If mechanical scanning is used to generate lateral image dimensions, then imaging capability is achieved, but scanning time increases and productivity decreases
Solution Approach 1:
The patent replaces mechanical scanning with a static multi-static transceiver arrangement. Instead of mechanically moving a single transceiver to sweep across the object, multiple transceivers are positioned in fixed spatial relationships to simultaneously illuminate different portions of the object. This eliminates mechanical movement while maintaining comprehensive imaging coverage, dramatically increasing scanning speed and productivity.
Solution Approach 2:
The system enables continuous simultaneous measurement across multiple spatial locations through the parallel operation of multiple transceiver pairs. While mechanical scanning performs measurements sequentially at different positions, the multi-static system conducts all measurements concurrently, maintaining continuous useful action throughout the measurement process and eliminating idle time between scans.
3Loss of information
If only axial image dimension is obtained through radar techniques, then depth information is provided, but material properties cannot be separated due to lack of polarization dependence
Solution Approach 1:
The patent adds polarization state as a new measurement dimension by arranging transceivers in multiple orientations. This enables simultaneous measurement of reflectivity coefficients for different polarization states (e.g., horizontal and vertical), providing additional independent equations needed to separate multiple material properties including depth, refractive index, and dielectric constant.
Solution Approach 2:
The patent introduces reflectivity coefficients as intermediary parameters that link the measured electromagnetic wave interactions to the material properties. By measuring reflectivity for multiple polarization states and using these coefficients as intermediaries in the inversion process, the system can uniquely determine multiple material properties that cannot be separated in conventional single-polarization radar.
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 the accurate extraction of complex permittivity and thickness of dielectric layers in objects, providing enhanced dielectric property determination and material identification, particularly for the sole of a shoe, by utilizing polarized radiation and frequency division multiplexing to reduce scanning time.
Implementation Method 1
a plurality of transceivers for generating radiation in the microwave or millimeter-wave region of the electromagnetic spectrum
Implementation Method 2
A partially reflected electromagnetic radiation from the shoe and structures/objects within the shoe provides the image features in the axial dimension, for example, at a discontinuity where the dielectric properties change
Implementation Method 3
analyzer for computing, for each of a plurality of pixels in the irradiated portion of the object, one or more reflectivity coefficients (reflectivity parameters), where each reflectivity coefficient is associated with a pair of transceivers positioned to irradiate the pixel and each reflectivity coefficient is proportional to a ratio of a signal detected by one of the pairs of transceivers in a frequency band relative to a signal transmitted by the other transceiver of the pair in that frequency band
Implementation Method 4
In a system in which such illumination and reception take place mono-statically, the reflection of radiation from isotropic materials is independent of radiation polarization. At normal incidence, the electric and magnetic field vectors are, by definition, perpendicular to the surface normal and therefore, for the case of an isotropic medium, there is no polarization dependence
Data Source
AI summary
In one aspect, a system for obtaining dielectric properties of an object is disclosed, which comprises a plurality of transceivers for generating radiation in the microwave or millimeter-wave region of the electromagnetic spectrum. The transceivers are positioned in spatially fixed relationships relative to one another. The system further includes a controller for selectively activating the transceivers for irradiating at least a portion of the object and detecting at least a portion of the radiation reflected from said portion of the object in response to the irradiation, where each of the activated transceivers generates a signal in response to detection of the reflected radiation. The reflected signals are analyzed to determine a plurality of reflectivity coefficients corresponding to different discrete locations of the object, and the reflectivity coefficients are used to determine the complex permittivity of the discrete locations.