RFID Tag Antenna Loop Inductance for Impedance Matching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing radio frequency identification (RFID) tags face challenges in impedance matching with circuit chips having small capacitance, leading to reduced communication distances and antenna gain when trying to maintain a compact size.
Innovation Solution
A radio frequency identification tag design featuring a resilient base sheet, an electronic component, a reinforcing member with a concave shape, and an antenna with a loop-shaped inductance portion and spiral dipole section, where the inductance portion is partly covered by the reinforcing member, ensuring sufficient length and width variations to achieve impedance matching with small capacitance circuit chips, and is encapsulated in resin for durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna size is reduced to maintain a compact tag size, then the tag becomes more compact, but the communication distance and antenna gain are reduced
Solution Approach 1:
The inductance portion is designed with a loop shape that extends in multiple dimensions, particularly utilizing the width dimension more effectively. The loop configuration allows the antenna to achieve sufficient inductance value and effective area without increasing the overall tag length, thereby maintaining compact size while preserving communication distance.
Solution Approach 2:
The antenna design applies different geometric characteristics to different portions: the inductance portion uses a loop shape with optimized width-to-length ratio to maximize inductance density, while the dipole portion maintains traditional geometry. This localized optimization allows the inductance portion to contribute more effectively to impedance matching within a compact footprint.
2Volume of moving object
If the antenna size is reduced to maintain a compact tag size, then the tag becomes more compact, but the antenna gain is reduced
Solution Approach 1:
The loop-shaped inductance portion increases the effective current path length and inductance value without proportionally increasing the physical footprint. By optimizing the loop geometry (width, height, and curvature), the antenna achieves higher inductance density, which improves impedance matching and thereby maintains antenna gain despite reduced overall size.
Solution Approach 2:
The antenna incorporates a resin layer with specific dielectric properties positioned adjacent to the inductance portion. This dielectric material concentrates electromagnetic fields in the region of the loop, enhancing the effective inductance and improving radiation efficiency, thus maintaining antenna gain in a compact configuration.
3Reliability
If the inductance portion width is increased to improve impedance matching, then the impedance matching improves, but the tag area increases
Solution Approach 1:
The loop configuration transforms the inductance generation from a primarily linear dimension (length) to a two-dimensional structure (width and height). This allows the antenna to achieve the required inductance value for impedance matching with small-capacitance chips while maintaining a compact overall area, as the loop encloses magnetic flux more efficiently than a straight conductor.
4Reliability
If the inductance portion length is increased to improve impedance matching, then the impedance matching improves, but the tag length increases
Solution Approach 1:
The loop-shaped inductance portion utilizes vertical and lateral dimensions rather than extending only in the longitudinal direction. By forming a closed loop with optimized width and height, the antenna achieves sufficient inductance value without increasing the tag length, allowing impedance matching to be achieved within a compact longitudinal 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 design enhances communication distance and maintains a compact size by securing sufficient antenna length and area, suppressing antenna gain reduction, and improving durability through resin encapsulation, while being compatible with various frequency bands.
Implementation Method 1
resonating the inductance of the antenna and the capacitance of the circuit chip
Implementation Method 2
The antenna includes an inductance section and a dipole section... performs impedance matching with the circuit chip
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A radio frequency identification tag includes: a resilient base sheet; an electronic component; a reinforcing member having at least one concave portion at a periphery of the reinforcing member; and an antenna including a dipole portion and an inductance portion, the inductance portion having an impedance matching with that of the electronic component and being formed in a loop shape; the inductance portion being partly covered by the reinforcing member, the loop shape of the inductance portion being narrowed where the loop shape runs under the concave portion of the periphery of the reinforcing member and being widened outside of the reinforcing member.