Passive RF Detection Plate with Inductive Coupler
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Solution Overview
Problem
Passive detection chips are susceptible to interference and range reduction when near electrically conductive objects, particularly metallic surfaces, due to galvanic or capacitive coupling issues.
Innovation Solution
Integration of a chip module with an inductive coupling element into an electrically conductive body, where the coupling element forms an opening that functions as an antenna, allowing non-galvanic coupling and impedance transformation, reducing susceptibility to interference and enabling reading of conductive objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive detection chip is arranged directly on a metal surface, then the reading distance is reduced or reading fails completely, but the device complexity and installation simplicity are improved
Solution Approach 1:
The patent introduces an intermediate coupling structure consisting of a conductive plate with an opening and a coupling element. This intermediary structure mediates between the chip and the metal surface, enabling electromagnetic coupling without direct contact. The coupling element transfers electromagnetic energy between the antenna formed by the opening and the chip terminals, while the conductive plate with opening provides impedance transformation, thereby resolving the contradiction between reading reliability and device complexity.
2Ease of manufacture
If a coupling element is galvanically coupled to the antenna, then the manufacturing is simpler, but the system becomes susceptible to interference from mechanical stress and corrosion
Solution Approach 1:
The coupling element serves as an intermediary that provides non-galvanic coupling between the chip and the antenna. By using electromagnetic coupling through the opening in the conductive plate rather than direct galvanic connections, the system achieves mechanical stress and corrosion resistance while maintaining manufacturability. The coupling element transfers energy inductively, eliminating the harmful effects of galvanic coupling.
3Adaptability or versatility
If the opening is completely enclosed by the electrically conductive body, then the antenna can be tuned to half or even multiple of half wavelength, but the geometric dimensions of the opening must be precisely controlled
Solution Approach 1:
The patent employs parameter changes by allowing the opening to be configured in different ways (completely enclosed or partially open) to achieve different tuning characteristics. When completely enclosed, the antenna resonates at half or even multiples of half wavelength; when open on one side, it resonates at quarter or odd multiples of quarter wavelength. This provides tuning flexibility while the coupling element compensates for dimensional variations, reducing the strictness of manufacturing precision requirements.
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
Enhances reading range and reliability by eliminating the need for contact with conductive bodies, providing a robust and sabotage-proof solution for identifying electrically conductive objects.
Implementation Method 1
The coupling element is designed as an inductive coupling element, namely as a coil. This type of coupling element enables the chip to be coupled non-galvanically to the antenna, so that contact with the electrically conductive body, which is susceptible to interference, is not necessary.
Implementation Method 2
A coupling element between the chip and the opening transfers electromagnetic energy between the antenna and the terminals of the chip and at the same time performs an impedance transformation.
Implementation Method 3
An opening that is completely enclosed by the electrically conductive body can be tuned to half or an even multiple of half the wavelength of the transmission and reception frequency by adjusting its geometric dimensions.
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
The plate has a chip (10) and an antenna including an electrical conductor with an opening (16), where geometric dimension of the opening is matched with a transmitting and receiving frequency of a reader system with the chip. A coupling member is arranged on or in the opening. The chip along with the coupling member forms a chip-module, and the coupling member is designed as an inductive or capacitive coupler.