Circularly Polarized Stripline Resonator for Spin Resonance Testing
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Solution Overview
Problem
Conventional stripline resonators in banknote processing machines create a linearly polarized radiofrequency field, leading to inefficient excitation of spin resonance features, with only half of the power being effective and the other half causing waste heat and reducing the signal-to-noise ratio.
Innovation Solution
A sensor element with a stripline resonator and feedline structure designed to create a circularly polarized radiofrequency field, using a geometry that includes a retardation line to achieve efficient excitation and detection of spin resonance, reducing power requirements and increasing sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional stripline resonator creating a linearly polarized radiofrequency field is used, then the excitation of spin resonance features can be achieved, but only half of the power is effective while the other half causes waste heat and reduces the signal-to-noise ratio
Solution Approach 1:
The patent changes the polarization parameter of the radiofrequency field from linear to circular. By using a circularly polarized field instead of a linearly polarized field, the excitation of spin resonance becomes fully efficient, eliminating the 50% power loss and associated waste heat that occurs with linear polarization.
2Measurement precision
If a conventional stripline resonator creating a linearly polarized radiofrequency field is used, then the excitation of spin resonance features can be achieved, but the sensitivity is reduced due to the signal-to-noise ratio degradation
Solution Approach 1:
The patent changes the polarization parameter of the radiofrequency field from linear to circular. This parameter change optimizes the interaction with spin resonance features, fully utilizing the available power for excitation and thereby improving the signal-to-noise ratio and measurement sensitivity.
3Use of energy by moving object
If a circularly polarized resonator design is used, then the sensitivity is enhanced and excitation power is reduced, but the device complexity increases due to the geometry requirements
Solution Approach 1:
The resonator structure is divided into two separate feedlines, each connected to opposite sides of the resonator. This segmentation allows independent control of the two orthogonal field components, enabling circular polarization while maintaining a relatively simple overall structure that can be manufactured using standard PCB techniques.
Solution Approach 2:
The patent introduces asymmetry through the use of two feedlines with different path lengths or impedance characteristics, which are necessary to create the 90-degree phase difference required for circular polarization. This controlled asymmetry enables the desired field polarization while maintaining manufacturing feasibility.
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
The circularly polarized resonator design enhances sensitivity by up to a factor of √2 and reduces excitation power by a factor of 2, improving the signal-to-noise ratio and reducing waste heat.
Implementation Method 1
designed to create a radiofrequency field with circular polarization, especially in the near field, by way of the geometry of the stripline resonator and/or the geometry of the feedline structure
Implementation Method 2
resonator device for exciting the spin resonance feature of the data carrier to be tested in the air gap. The spin resonance feature is preferably an ESR feature
Implementation Method 3
a polarization device for creating a static magnetic flux in the air gap
Implementation Method 4
The spin resonance signatures that can be used for authenticity testing include, in particular, nuclear magnetic resonance (NMR) effects, electron spin resonance (ESR) effects, and ferromagnetic resonance (FMR) effects
Data Source
AI summary
A sensor element is for testing a planar data carrier that has a spin resonance feature. The sensor element includes: a magnetic core having an air gap into which the planar data carrier can be inserted for testing purposes; a polarization device for generating a static magnetic flux in the air gap; and a resonator device for exciting the spin resonance feature of the data carrier to be tested in the air gap. The resonator device has a stripline resonator and a supply structure for the stripline resonator and is designed to generate a high-frequency field with circular polarization owing to the geometry of the stripline resonator and/or the geometry of the supply structure.