Resonant Circuit with Localized Capacitance for Low Frequency
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Solution Overview
Problem
Conventional RFID resonant circuits face challenges in achieving low resonance frequencies without increasing coil size, which degrades communication characteristics due to reduced coil opening.
Innovation Solution
The resonant circuit design features coil-shaped conductors with increased capacitance in outermost and innermost windings and decreased capacitance in middle sections, allowing for a lower resonance frequency without enlarging the coil, while maintaining or reducing the coil's size and enhancing communication performance by increasing the coil opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the coil size is increased to achieve a lower resonance frequency, then the resonance frequency is lowered, but the communication characteristics are degraded due to reduced coil opening
Solution Approach 1:
The patent applies local quality by making the outermost and innermost windings of the coil have different properties from the middle windings. Specifically, the outermost and innermost windings are configured to have larger cross-sectional areas, which increases the capacitance in these regions. This localized modification allows the resonance frequency to be lowered without increasing the overall coil size, thereby maintaining good communication characteristics.
2Reliability
If the capacitance is increased to lower the resonance frequency, then the resonance frequency is lowered, but the coil size must be increased which degrades communication performance
Solution Approach 1:
The invention increases capacitance locally at the outermost and innermost windings rather than uniformly across the entire coil. This is achieved by making these specific windings have larger cross-sectional areas, which increases the capacitance in these regions without requiring an increase in the overall coil area, thus lowering resonance frequency while maintaining communication performance.
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 effectively achieves a low resonance frequency without enlarging the coil, improving communication performance by allowing more flux through the coil opening and maintaining a balanced inductance and capacitance configuration.
Implementation Method 1
a capacitance interposed therebetween
Implementation Method 2
the inductance of the two coil-shaped conductors and the capacitance generated between the both coil-shaped conductors
Implementation Method 3
The resonance circuit is set to have a predetermined resonance frequency by the inductance of the two coil-shaped conductors and the capacitance generated between the both coil-shaped conductors
Data Source
AI summary
A resonant circuit and an antenna device achieve a low resonance frequency without increasing a coil size, and improve communication performance. In the resonant circuit, two coil-shaped conductors are arranged so as to be opposed to each other with a dielectric sheet interposed therebetween. The two coil-shaped conductors are, at the opposed portions thereof, coupled with a capacitance interposed therebetween, and wound so that electric currents flowing through the respective conductors trend in the same direction in a planar view. The opposed area in at least a portion of the outermost windings and/or innermost windings of the coil-shaped conductors is larger as compared with the opposed area in any other winding, and the respective ends of the conductors define power feeding units.