Compact Passive UHF RFID Tag With Switchable Impedance
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Solution Overview
Problem
Current passive UHF RFID tags are limited in size, read range, and geographic flexibility, making them unsuitable for emerging applications in high-density environments with varied material influences and global usage requirements.
Innovation Solution
The proposed UHF RFID tag architecture incorporates a reduced matching loop size by moving inductance value into the integrated circuit, adds a capacitance boost for enhanced energy harvesting, and includes switchable impedance to adapt to different frequency bands and geographic regions, enabling smaller size, longer read range, and global compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a passive UHF RFID tag uses a traditional matching loop design, then it can achieve adequate impedance matching, but the tag footprint becomes too large for emerging applications
Solution Approach 1:
The patent combines the matching loop and antenna into a unified integrated structure where the antenna serves dual purposes: radiation and impedance matching. This integration eliminates the need for a separate matching loop, significantly reducing the tag footprint while maintaining matching performance through optimized antenna geometry and positioning the integrated circuit at the antenna center.
Solution Approach 2:
The patent transitions from a planar matching loop design to a three-dimensional antenna structure with vertical elements. By utilizing the Z-dimension (height) in addition to the X-Y plane, the antenna achieves effective impedance matching and radiation performance in a compact footprint, allowing the tag to maintain reliability while reducing area.
2Area of moving object
If a passive UHF RFID tag uses a compact design, then the tag size is reduced, but the read range decreases
Solution Approach 1:
The patent implements switchable impedance circuits that allow the antenna to dynamically adjust its electrical characteristics based on operating conditions. This dynamic adaptation enables the compact antenna to optimize its radiation efficiency and impedance matching across different frequencies and loading conditions, maintaining read range performance despite the reduced physical size.
Solution Approach 2:
The patent employs variable capacitance and inductance values through switchable circuits to change the electrical parameters of the antenna system. By adjusting these parameters, the compact antenna structure achieves resonance at the desired frequency with optimal radiation efficiency, compensating for the size reduction and maintaining adequate read range.
3Adaptability or versatility
If a passive UHF RFID tag uses fixed impedance design, then the circuit is simpler, but the tag cannot adapt to different frequency bands and geographic regions
Solution Approach 1:
The patent implements switchable impedance circuits with multiple selectable capacitance and inductance values that allow the tag to dynamically adapt to different frequency bands and geographic regions. The switching mechanism enables reconfiguration of the antenna system's electrical characteristics without requiring completely different antenna designs for each region.
Solution Approach 2:
The patent designs a universal antenna structure with integrated switching capability that can operate across multiple frequency bands and geographic regions. This multi-functional design allows a single tag platform to serve global markets by electronically reconfiguring its impedance to match different regional RFID standards, eliminating the need for region-specific tag variants.
4Use of energy by moving object
If a passive UHF RFID tag collects power through a traditional matching loop, then power transfer is adequate, but the tag size increases
Solution Approach 1:
The patent merges the power collection function with the radiation function by using the antenna itself as the primary power harvesting element. The integrated circuit is positioned at the antenna center where electromagnetic field coupling is maximized, enabling efficient power transfer without requiring a separate matching loop structure.
Solution Approach 2:
The patent utilizes vertical positioning in the Z-dimension to optimize power collection. By placing the integrated circuit at the center of the antenna structure along the vertical axis, the design maximizes coupling with the electromagnetic field generated by the antenna, achieving efficient power transfer in a compact planar footprint.
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 solution allows for smaller, more versatile RFID tags with increased read range and adaptability, addressing the limitations of existing tags in size, material compatibility, and geographic flexibility, enhancing performance in diverse applications and supply chain efficiency.
Implementation Method 1
Passive UHF RFID tags collect power radiated from the RFID reader
Implementation Method 2
transfer the collected power to the integrated circuit via a matching loop circuit
Data Source
Figure 1A~1B
Figure 2~4
Figure 5
AI summary
The present invention is in the field of ultra-high frequency ("UHF") radio frequency identification ("RFID") tags. More particularly, the present invention relates generally to systems and methods for providing a passive UHF RFID tag having a small footprint that is optimized for high performance applications in emerging markets for RFID technology.