Non-Closed Loop Emitter for Dielectric Inhomogeneity Detection
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Solution Overview
Problem
Existing systems for detecting dielectric irregularities in objects using electromagnetic fields face challenges such as poor coupling, surface wave generation, and patient discomfort due to the need for close contact with high permittivity tissues like human breasts or heads, which are compounded by the magnetic wall effect and limitations in wave propagation.
Innovation Solution
A system employing a non-closed loop emitter with a slit, producing a dominant axial magnetic field and minimizing external electric fields, combined with resonant probes sensitive to radially directed electric fields, allows for internal wave propagation and detection of dielectric inhomogeneities without exciting external surface waves, using a low-impedance feed line and high-permittivity ceramic structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional antennas (coaxial endfire, circular TM01 mode) are used for microwave detection, then coupling to the object under study can be achieved, but surface waves are excited and energy penetration is limited to shallow depths
Solution Approach 1:
The antenna structure is segmented into multiple orthogonal components (x-directed and y-directed dipoles) that can be independently controlled. This segmentation allows selective excitation of bulk waves while canceling surface wave components through proper phase and amplitude control of each segment.
Solution Approach 2:
The antenna uses asymmetric configuration with orthogonal dipoles of different lengths and orientations. The x-directed dipole is optimized for one polarization while the y-directed dipole handles the orthogonal polarization, creating asymmetric field patterns that favor bulk wave propagation over surface waves.
2Reliability
If high permittivity dielectric filling is used in the applicator to achieve magnetic wall effect, then resonant standing wave with dominant electric field parallel to OUS interface is achieved, but energy penetration depth is limited to about five millimeters
Solution Approach 1:
The antenna operates in a dynamic regime where the dipole lengths are optimized to resonate at the operating frequency, creating a standing wave pattern that maximizes electric field strength at the interface while maintaining proper impedance matching. This dynamic resonance condition enhances coupling without requiring high permittivity materials.
Solution Approach 2:
The design changes the operating parameters by using air-filled structure instead of high permittivity dielectric filling. The dipole lengths and spacing are adjusted as key parameters to achieve the desired field distribution and penetration depth without relying on material permittivity enhancement.
3Adaptability or versatility
If patch antennas are used for detection, then frequency bandwidth is improved, but impedance matching problems occur requiring immersion in external liquid bolus which causes patient discomfort
Solution Approach 1:
The antenna structure is self-matching through its geometric design. The orthogonal dipole configuration and spacing are optimized to provide automatic impedance matching to standard 50-ohm transmission lines without requiring external matching networks or immersion media. The structure serves its own impedance matching function.
4Adaptability or versatility
If Vivaldi antennas are used for broadband detection, then frequency bandwidth and beam width are improved, but electromechanical design becomes complicated requiring very tight tolerances resulting in expensive antennas
Solution Approach 1:
The antenna uses simple, inexpensive dipole elements that can be manufactured with relaxed tolerances using standard PCB or wire techniques. These simple structures replace the complex, precision-machined Vivaldi geometry, significantly reducing manufacturing cost and complexity while maintaining adequate broadband performance through the orthogonal configuration.
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
This approach enables effective localization and characterization of inhomogeneities within high permittivity tissues like the human head without surface wave interference, providing improved spatial resolution and reduced system complexity, allowing for non-invasive and comfortable measurements.
Implementation Method 1
A system employing a non-closed loop emitter with a slit, producing a dominant axial magnetic field and minimizing external electric fields, combined with resonant probes sensitive to radially directed electric fields, allows for internal wave propagation and detection of dielectric inhomogeneities
Implementation Method 2
combined with resonant probes sensitive to radially directed electric fields
Implementation Method 3
using a low-impedance feed line and high-permittivity ceramic structures
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
A system and method, as well as sub assemblies thereof, for detection of dielectric irregularities/inhomogeneities inside an object under study (OUS) be means of electromagnetic energy are disclosed. The system comprises a loop/cylinder emitter configured to be located close to the OUS with its axis of symmetry directed towards the OUS. A feeding line feeds the emitter with an alternating current at an operating frequency to cause a magnetic field therein, which in turn will induce a propagating electromagnetic field in the OUS. In order to reduce propagating fields outside of the OUS, the circumference of the emitter is smaller than the free-space wavelength corresponding to the operating frequency, and the feeding line has a characteristic impedance that is smaller than 20 Ohm.