RFID Tag Antenna Asymmetric Folding Circuit Reduces Metal Coverage
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Solution Overview
Problem
Current RFID tags face challenges in reducing metal usage and cost due to the large metal coverage rate in their antennas, which limits further material and cost reduction.
Innovation Solution
The implementation of a folding circuit with an open terminal and a hollow radiation part, which is asymmetric to the chip contact part, reduces metal coverage rates and enhances radiation efficiency by maintaining consistent current flow, thereby reducing the overall metal usage and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the metal coverage rate in the RFID tag antenna is increased to compensate for the short antenna electric length, then the antenna radiation efficiency is improved, but the material cost and manufacturing cost increase
Solution Approach 1:
The antenna is divided into two distinct functional parts: a folding circuit portion and a radiation portion. The folding circuit uses meandering metal traces to achieve the required electrical length for impedance matching and signal folding, while the radiation portion uses minimal metal structures optimized for electromagnetic radiation. This segmentation allows each part to perform its specific function with optimal metal usage.
Solution Approach 2:
The folding circuit employs meandering traces that fold the signal path in the planar dimension, effectively increasing the electrical length without proportionally increasing the physical footprint. This dimensional folding allows the antenna to achieve the required 900 MHz wavelength compensation within the constrained 1×4 inch tag area while minimizing overall metal coverage.
2Reliability
If the antenna electric length is compensated using traditional meandering design, then the radiation efficiency is maintained, but the metal coverage rate becomes too large to reduce cost further
Solution Approach 1:
The antenna is divided into two distinct functional parts: a folding circuit portion and a radiation portion. The folding circuit uses meandering metal traces to achieve the required electrical length for impedance matching and signal folding, while the radiation portion uses minimal metal structures optimized for electromagnetic radiation. This segmentation allows each part to perform its specific function with optimal metal usage.
Solution Approach 2:
Different regions of the antenna are designed with different metal trace densities and patterns. The folding circuit region uses dense meandering traces to achieve electrical length compensation, while the radiation region uses sparser, optimized trace patterns. This local differentiation optimizes performance in each region while minimizing overall metal consumption and manufacturing cost.
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 design achieves a lower metal coverage rate, reducing the RFID tag's cost while maintaining or improving the antenna's radiation efficiency and read range, as demonstrated by various embodiments with different configurations.
Implementation Method 1
The tag antenna of the RFID tag will perform wireless transmission between the reader, to obtain required data
Data Source
AI summary
A radio frequency identification (RFID) tag including a substrate, an RFID chip, a chip contact part, a folding circuit and a radiation part is provided. The chip contact part is formed on the substrate and electrically coupled to the RFID chip. The folding circuit is formed on the substrate and electrically coupled to the chip contact part. The folding circuit has a winding part, which forms a hollow region, for compensating the antenna electric length. The radiation part is formed on the substrate and electrically coupled to the folding circuit, wherein one terminal of the winding part of the folding circuit is open, and the other terminal is electrically coupled to the radiation part. At least one of the folding circuit and the radiation part is asymmetric to the chip contact part.