Tunable RFID Tag Antenna With Removable Conductive Bridges
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Solution Overview
Problem
UHF RFID tags face challenges in metallic environments due to energy loss and temperature limitations, requiring tunable antennas that can maintain resonance frequency without additional circuitry and withstand higher temperatures without performance degradation.
Innovation Solution
A passive RFID tag with a slotted antenna design featuring removable conductive bridges that adjust the resonance frequency by varying the electrical path length, allowing for easy tuning and compensation of gas accumulation issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a slotted antenna design is used for UHF RFID tags in metallic environments, then the readability and energy collection are improved, but the resonance frequency becomes sensitive to gas accumulation underneath the inlay
Solution Approach 1:
The patent applies preliminary action by pre-defining multiple conductive bridge configurations that correspond to different resonance frequencies. These bridges are positioned in advance on the substrate, and the appropriate configuration is selected and connected before deployment based on the specific application requirements, preventing frequency drift issues from arising in the first place
Solution Approach 2:
The patent implements parameter changes by providing multiple conductive bridge configurations with different geometries (lengths, positions, patterns) that alter the electrical characteristics of the antenna. By selecting and connecting appropriate bridges, the resonance frequency and impedance parameters can be adjusted to compensate for gas accumulation effects and optimize performance for specific frequency bands
2Adaptability or versatility
If additional circuitry is added for frequency tuning, then the resonance frequency can be adjusted, but the cost and device complexity increase
Solution Approach 1:
The patent extracts the frequency tuning function from complex active circuitry and implements it through passive conductive bridge configurations. The bridges are simply conductive traces or elements that are either present or removed/ disconnected, eliminating the need for active tuning circuits, capacitors, inductors, or control electronics while still achieving frequency adjustment
Solution Approach 2:
The patent uses simple, inexpensive conductive bridges that can be manufactured as part of the standard antenna structure using the same printing or etching processes. These bridges are basic conductive elements without complex functionality, significantly reducing manufacturing cost compared to active tuning circuits
3Adaptability or versatility
If the antenna path length is increased to lower the resonance frequency, then the frequency can be adjusted, but the antenna size increases
Solution Approach 1:
The patent utilizes another dimension by adding conductive bridges that create additional current paths in the vertical or lateral dimension rather than simply extending the antenna path length in one direction. The bridges connect different parts of the slot antenna structure, effectively adding electrical length through three-dimensional routing while maintaining a compact two-dimensional footprint on the substrate
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 efficient frequency adjustment and prevents gas-induced detuning, ensuring reliable performance in metallic environments and high temperatures without additional circuitry or energy losses.
Implementation Method 1
Said two contact pads are electrically connected respectively each to one of the first and second part of the antenna
Implementation Method 2
removal of said conductive bridge changes the resonance frequency of the passive RFID tag by varying the length of the electrical path
Data Source
Figure 1~2
Figure 2A~3
Figure 4~5
AI summary
The RFID tag comprises an antenna (11) connected to a wireless communication device (18). The antenna comprises a conductive planar surface and a slot (14) extending at least in a part of said conductive planar surface, the slot (14) forming a non-conductive area of the antenna and defining a first part (12) and a second part (13) of the antenna. The wireless communication device comprises two contact pads (16, 17) being electrically connected respectively each to one of the first and second part of the antenna. The slot comprises a closed end formed by a further conductive part connecting said first and second parts the antenna and further comprises at least one conductive bridge (19-19"', 20, 21-21 ") connecting said first and second parts of the antenna, the conductive bridge allowing to tune the resonance frequency of the tag by varying the length of the electrical path between the pads from the wireless communication device in the antenna.