Sensor Tag Antenna Design for Stable Radiation Frequency
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Solution Overview
Problem
Existing sensor tags experience measurement errors due to changes in antenna impedance, which affect the frequency of the signal radiated, even when the resonant frequency of the resonator remains constant, leading to inaccuracies in temperature and other physical quantity measurements.
Innovation Solution
A sensor tag design where the antenna is formed such that the resonant frequency ratio between the resonator and the antenna's self-resonant frequency remains within a certain range, minimizing frequency variations by controlling the inductance ratio, and determining the antenna shape based on specific criteria to maintain a stable radiation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the antenna shape is changed to adapt to different modes of use, then the adaptability of the sensor tag is improved, but the impedance of the antenna changes causing the radiated signal frequency to shift and measurement precision to deteriorate
Solution Approach 1:
The patent applies parameter changes by establishing specific mathematical relationships between the resonant frequency ratio (frF) and inductance ratio (frL) to control antenna design parameters. By setting frF within specific ranges based on frL values, the antenna maintains stable radiation frequency despite shape changes, resolving the contradiction between adaptability and measurement precision
Solution Approach 2:
The patent implements preliminary anti-action by pre-determining the antenna's resonant frequency and inductance characteristics during design to counteract future frequency shifts. By setting the resonant frequency ratio within specific ranges based on expected inductance ratios, the design proactively prevents measurement errors before they occur during actual use
2Adaptability or versatility
If the antenna shape is changed, then the versatility of the sensor tag is improved, but the frequency of the radiated signal varies causing temperature measurement errors
Solution Approach 1:
The patent uses parameter changes by defining specific functional relationships between resonant frequency ratio and inductance ratio. By controlling these parameters within established ranges, the antenna can adapt its shape for different applications while maintaining stable radiation frequency, thus improving versatility without sacrificing measurement accuracy
3Device complexity
If the resonant frequency ratio is not controlled, then the antenna design is simple, but the frequency variation of radiated signal increases leading to measurement errors
Solution Approach 1:
The patent applies parameter changes by establishing specific ranges for the resonant frequency ratio based on inductance ratio. This controlled parameter approach ensures measurement precision while avoiding excessive design complexity, as the parameters follow clear mathematical relationships rather than requiring complex optimization algorithms
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 approach suppresses variations in the resonator's characteristics, enabling accurate measurement of physical quantities by keeping the radiation signal frequency within a predetermined range, even when the antenna shape changes.
Implementation Method 1
a resonator that resonates at a resonant frequency corresponding to a sensed physical quantity
Implementation Method 2
an antenna that radiates a signal generated by the resonance of the resonator to the outside
Data Source
AI summary
A sensor tag (10) includes a crystal vibrator (110) and an antenna (102). The antenna (102) is composed of a radiating conductor (121) and connection conductors (122). A crystal vibrator (110) is mounted on land conductors (120) provided at an end portion of the connection conductors (122) on the opposite side to the antenna (121). The antenna (102) is formed in a shape such that an amount of shift (ΔF) of a radiation frequency of the sensor tag (10) falls within an acceptable range in accordance with a resonant frequency (Fxs) and an equivalent inductance (Lxs) of the crystal vibrator (110) and a self-resonant frequency (Fant) and an equivalent inductance (Lant) of the antenna (102).