RFID Tag Antenna Shunt for Selective State Switching
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Solution Overview
Problem
Conventional RFID tags lack the ability to selectively change their antenna characteristics in response to mechanical or positional changes, limiting their application in scenarios requiring conditional authentication or privacy until a product is opened or a specific state is reached.
Innovation Solution
A modifiable RFID tag structure featuring a dielectric substrate with a conductive shunt that alters the antenna's electrical length, allowing it to switch between transmissive and non-transmissive states based on mechanical contact or positional changes, enabling conditional communication with a reader.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an RFID tag is designed to be always transmissive, then authentication capability is improved, but security and privacy control deteriorate because the tag cannot remain hidden until needed
Solution Approach 1:
The patent applies the dynamics principle by making the RFID tag's antenna characteristic changeable through a mechanical state machine. The antenna transitions between different electrical lengths based on the mechanical state (latched or unlatched), enabling the tag to dynamically switch between transmissive and non-transmissive states. This resolves the contradiction by allowing the tag to be always capable of authentication while controlling when it actually transmits signals.
Solution Approach 2:
The patent changes the electrical length parameter of the antenna based on mechanical state. When the state machine is in one state, the antenna has a first electrical length that enables communication; when in another state, it has a second electrical length that prevents communication. This parameter change allows the tag to maintain authentication capability while controlling transmission timing, resolving the security-privacy contradiction.
2Adaptability or versatility
If an RFID tag is designed to be non-transmissive by default, then security and privacy are improved, but authentication capability deteriorates because the tag cannot be read from a distance
Solution Approach 1:
The dynamics principle enables the antenna to transition between non-transmissive and transmissive states based on mechanical activation. The tag starts in a non-transmissive state for privacy protection but can be switched to a transmissive state when needed for authentication, thus maintaining both privacy control and authentication capability.
Solution Approach 2:
The tag is pre-configured in a non-transmissive state before authentication is needed. The mechanical state machine is initially set to prevent transmission, and only when the proper mechanical action is taken (latching or unlatching) does the tag become transmissive. This preliminary configuration ensures privacy while enabling on-demand authentication.
3Adaptability or versatility
If a conductive shunt is used to alter antenna electrical length, then conditional transmission capability is improved, but device complexity increases due to additional mechanical components
Solution Approach 1:
The patent segments the antenna into sections that can have their electrical length altered by the conductive shunt. The shunt acts as a separate component that can be mechanically positioned to change the effective antenna length. This segmentation enables selective response capability while keeping the mechanical structure relatively simple and modular.
Solution Approach 2:
The conductive shunt serves as an intermediary element between the mechanical state machine and the antenna. It translates mechanical state changes into electrical length changes of the antenna, enabling conditional transmission capability without requiring direct mechanical modification of the antenna structure itself.
4Adaptability or versatility
If the antenna electrical length is made changeable, then conditional authentication capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
By segmenting the antenna and using a conductive shunt to alter its effective length, the patent reduces manufacturing precision requirements. Instead of manufacturing antennas with precisely different lengths, the base antenna is manufactured once, and the shunt is positioned to create the desired electrical length change. This segmentation approach simplifies manufacturing while maintaining state-dependent communication capability.
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
Enables secure authentication and privacy by allowing the RFID tag to respond only when the product is opened or in a specific state, enhancing security and authentication capabilities in various applications.
Implementation Method 1
A conductive shunt conductively contacts the antenna at least at the first location and extends from the first location so as to define an antenna pattern having a second electrical length that is different than the first electrical length
Implementation Method 2
the substrate of the tag can comprise a material that dielectrically loads the antenna such that the antenna pattern has a physical length corresponding to the first electrical length that is less than would be required of the same antenna pattern in free space
Data Source
AI summary
A tag for RFID applications and the like comprises an antenna supported on a dielectric substrate and having a first electrical length suitable for communication as a transponder. A selectively removable conductive shunt causes the antenna to assume a second electrical length which impedes transponder communication. Applications of the tag include tag-bearing products that are non-transmissive beneath surrounding packaging, and state machines that change between transmissive and non-transmissive states with selective shunting of the antenna. A method for enhancing an RFID tag for selective operation is also provided.