Chipless RFID Antenna Phase Encoding
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Solution Overview
Problem
Current RFID systems in libraries face challenges due to high costs, limited read range, and inefficiencies in identifying and tracking items with chipless RFID tags, particularly in environments where tags are in close proximity, such as stacked books.
Innovation Solution
A chipless radio frequency transponder system using stub loaded microstrip patch antennas (SLMPAs) on a substrate, which generates a unique identification code from the phase difference of backscattered signals in orthogonal polarization planes, allowing for efficient and cost-effective identification without microcontrollers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If RFID tags include microcontrollers to store and process identification codes, then the identification capability and data storage are improved, but the cost of the tags increases significantly
Solution Approach 1:
The patent extracts and removes the microcontroller component from the RFID tag, retaining only the essential antenna structure. The identification function is achieved through the antenna's resonant characteristics rather than active electronic components, thereby eliminating the primary cost driver while maintaining identification capability.
Solution Approach 2:
The patent employs passive, disposable antenna structures that can be easily manufactured and discarded. These chipless tags use simple resonant elements without expensive microcontrollers, making them suitable for single-use or short-duration applications where cost is critical.
2Productivity
If RFID tags are placed in close proximity to increase identification efficiency, then the tracking productivity is improved, but the signal interference and measurement precision deteriorate
Solution Approach 1:
The patent transitions from frequency-domain differentiation to polarization-domain differentiation. By using orthogonally polarized interrogation signals and measuring phase differences in the backscattered signals, the system can distinguish between closely spaced tags without relying on frequency separation, thereby maintaining measurement precision while improving identification efficiency.
Solution Approach 2:
The patent changes the measurement parameter from frequency to polarization phase. Instead of measuring resonant frequency differences, the system measures phase differences in backscattered signals with orthogonal polarizations, enabling precise differentiation of tags in close proximity.
3Area of stationary object
If the read range of RFID tags is extended to cover larger areas, then the coverage area is improved, but the signal strength and reliability worsen
Solution Approach 1:
The patent combines multiple orthogonal polarization components to extract the identification code. By interrogating with both horizontally and vertically polarized signals and combining the phase difference information, the system achieves more reliable signal detection and extends the effective read range while maintaining reliability.
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 system provides a cost-effective, efficient, and reliable method for identifying and tracking items with a reasonable read range, capable of encoding multiple bits of data and distinguishing between tags in close proximity, enhancing the adoption of RFID technology in libraries.
Implementation Method 1
the antenna having a shape determining a corresponding resonant frequency of the antenna
Implementation Method 2
the antenna causes a phase difference between backscattered signals generated in response to excitation of the antenna by orthogonally polarized interrogation signals at the resonant frequency
Implementation Method 3
orthogonally polarized interrogation signals
Data Source
AI summary
Various embodiments relate to a radio frequency transponder. In one embodiment, the transponder includes: a substrate and at least one planar antenna on the substrate, the antenna having a shape determining a corresponding resonant frequency of the antenna, wherein the antenna is configured to cause a phase difference between backscattered signals generated in response to excitation of the antenna by orthogonally polarized interrogation signals at the resonant frequency, and the phase difference represents a code of the antenna.