RFID Tag Reading Antenna with Split Ring Resonator for Metal Surfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing RFID tag reading antennas struggle to communicate effectively with RFID tags attached to or embedded within metal surfaces due to resonance frequency displacement and reduced power communication.
Innovation Solution
The design incorporates a loop antenna with a peripheral length shorter than a ¼ wavelength and a resonator with a smaller opening, positioned away from the loop antenna, allowing for effective communication with RFID tags on or inside metal members by minimizing resonance frequency displacement and magnetic field interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small loop antenna is used for RFID tag reading, then the antenna size is reduced and portability is improved, but the antenna cannot communicate effectively with RFID tags attached to metal surfaces due to resonance frequency displacement
Solution Approach 1:
The antenna system is divided into two separate components: a first loop antenna for generating magnetic flux and a second loop antenna functioning as a resonator. This segmentation allows each component to be optimized independently - the first antenna can be small for portability while the second antenna handles the resonance frequency matching required for metal surface communication.
Solution Approach 2:
The first loop antenna acts as an intermediary between the signal source and the RFID tag on metal surfaces. It generates magnetic flux that couples with the second loop antenna (resonator), which then communicates with the RFID tag. This intermediary structure allows the system to maintain small overall size while achieving reliable communication through the resonator's frequency-matched interface.
2Power
If the loop antenna is positioned close to the RFID tag for better coupling, then the coupling performance is improved, but the resonance frequency is greatly displaced when the tag is on a metal surface
Solution Approach 1:
By separating the coupling function (first loop antenna) from the resonance function (second loop antenna), the system achieves both strong coupling and frequency stability. The first antenna can be positioned close to the tag for strong magnetic coupling, while the second antenna maintains stable resonance frequency by being positioned away from the metal surface.
Solution Approach 2:
The first loop antenna serves as an intermediary that transfers magnetic flux to the second loop antenna without requiring the second antenna to be close to the metal surface. This mediator structure decouples the positioning requirements - the first antenna provides the coupling power while the second antenna maintains frequency stability.
3Manufacturing precision
If the resonator opening is made smaller to reduce metal interference, then the resonance frequency stability is improved, but the coupling area with the RFID tag is reduced
Solution Approach 1:
The coupling area function is assigned to the first loop antenna while the resonance function with controlled opening size is assigned to the second loop antenna. This segmentation allows the first antenna to provide sufficient coupling area without compromising the resonance frequency stability of the second antenna, which maintains a smaller opening to reduce metal interference.
Solution Approach 2:
The first loop antenna acts as an intermediary that provides the necessary coupling area and magnetic flux generation, allowing the second loop antenna (resonator) to maintain a smaller opening for frequency stability. The intermediary first antenna compensates for the reduced coupling area of the second antenna.
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 configuration enables reliable communication with RFID tags on or inside metal surfaces by maintaining the resonance frequency and enhancing coupling performance, even in close proximity to metal members.
Implementation Method 1
a loop antenna including a first loop-shaped conductor
Implementation Method 2
a resonator including a second loop-shaped conductor having an opening smaller than an opening of the first loop-shaped conductor
Data Source
AI summary
An RFID tag reading antenna includes a loop antenna including a first loop-shaped conductor having a peripheral length shorter than a ¼ wavelength in a communication frequency; and a split ring resonator including a second loop-shaped conductor having an opening smaller than an opening of the first loop-shaped conductor of the loop antenna and being arranged at a position away from a plane formed by the first loop-shaped conductor by a predetermined distance. In addition, the RFID tag reading antenna is coupled to an RFID tag as a communication partner, in a state where a distance from the RFID tag to the split ring resonator is shorter than a distance from the loop antenna to the split ring resonator.