RFID Tag Antenna Design for Selective Communication
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Solution Overview
Problem
Existing RFID tag communication systems face challenges in selectively communicating with specific tags among multiple parallel tags, as they often result in interference and inefficient communication ranges.
Innovation Solution
A communication antenna with a ground layer and a rectangular radiating section, along with an RFID tag design featuring a main antenna portion and folded-over antenna portions, allows for controlled short-distance communication by optimizing electric field radiation and sensitivity distribution, thereby limiting the communication range to specific tags.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional RFID antenna is used for communication with multiple parallel tags, then communication range is extended, but interference between tags occurs and individual tag communication becomes difficult
Solution Approach 1:
The patent applies local quality by creating a highly directional radiation pattern concentrated in a specific angular range (±15 degrees from the normal direction). This is achieved through the specific antenna structure with ground layer and radiating section having controlled dimensions and spacing, which localizes the electromagnetic energy distribution to communicate reliably with individual tags while minimizing interference with adjacent tags.
Solution Approach 2:
The patent employs asymmetry in the antenna geometry, where the radiating section has a specific width-to-length ratio and is positioned at a determined height above the ground layer. This asymmetric configuration produces an asymmetric radiation pattern that concentrates energy in the desired direction rather than uniformly in all directions, thereby reducing multi-tag interference.
2Area of stationary object
If the radiating section width is increased to improve communication range, then more tags can be reached, but the communication range becomes too broad and cannot limit to specific tags
Solution Approach 1:
The patent applies parameter changes by optimizing the radiating section width to a specific range (0.3 mm to 10 mm) and controlling the height above ground layer to be between 1/512 and 1/64 of the wavelength. These parameter adjustments create a radiation pattern that provides sufficient coverage area while maintaining precise angular discrimination to communicate with specific tags only.
3Reliability
If the interval between radiating section and ground layer is increased to enhance radiation efficiency, then communication sensitivity improves, but the antenna size increases and portability decreases
Solution Approach 1:
The patent applies parameter changes by defining the interval between the radiating section and ground layer as a specific fraction of the wavelength (1/512 to 1/64 λ). This parameter optimization achieves high communication sensitivity through enhanced radiation efficiency while keeping the antenna thickness minimal, thus maintaining portability and suitability for tag applications.
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 efficient short-distance communication with specific RFID tags while minimizing interference with other tags, ensuring high sensitivity and resonance frequency alignment, even when tags are closely spaced.
Implementation Method 1
the predetermined direction, that is the longitudinal direction of the radiating section, functions as a linear polarization plane
Implementation Method 2
an electric field is radiated efficiently in the direction in which the linear polarization characteristic is high
Implementation Method 3
the communication antenna has a resonance frequency corresponding to a frequency of radio waves used in communication
Data Source
AI summary
A communication antenna has a rectangular radiating section, and has a structure that emits an electric field of linear polarized waves only in a vicinity of the radiating section of the antenna. An RFID tag has an IC chip and a tag antenna that is long in a predetermined direction. The tag antenna has a main antenna portion that is rectilinear and extends over substantially an entire length in a longitudinal direction of the tag antenna, and folded-over antenna portions at which currents induced by an external electric field offset one another due to portions that extend in mutually different orientations in the longitudinal direction. A parallel interval between the main antenna portion and a first folded-over antenna portion exceeds a width of the radiating section of the communication antenna.