Offset Tag Antenna Structure for Stacked RFID Read Accuracy
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Solution Overview
Problem
Conventional information carriers experience read problems when stacked due to coupling effects among them, especially when aligned, leading to difficulties in accurately retrieving information from each carrier.
Innovation Solution
The information carrier and tag antenna structure feature a carrying sheet, a sheet-like insulating protector, and a tag antenna with an annular segment and extending segments, where the annular segment's central axis is offset from the carrying sheet's central axis by a significant distance, improving read performance by reducing impedance changes and matching losses when stacked.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional information carriers are stacked together with aligned tag antennas, then the structure is simple and easy to manufacture, but the reader cannot accurately read the information stored in each carrier due to coupling effects
Solution Approach 1:
The patent applies asymmetry by offsetting the central axis of the annular segment from the central axis of the carrying sheet. This asymmetric arrangement causes the electromagnetic fields of stacked antennas to be misaligned, reducing coupling effects between adjacent carriers and enabling accurate reading of information from each carrier in the stack.
Solution Approach 2:
The patent introduces a new dimensional parameter - the offset distance between the two central axes. By adding this axial offset dimension to the traditional concentric design, the patent creates spatial separation of electromagnetic fields in the stacked configuration, reducing interference while maintaining the same two-dimensional antenna pattern on each carrier.
2Quantity of substance
If conventional information carriers are stacked together, then the quantity of information carriers increases, but impedance changes and matching losses increase making reading difficult
Solution Approach 1:
The asymmetric offset arrangement reduces electromagnetic coupling between stacked carriers, which directly reduces energy loss through unwanted interactions. This allows a greater number of carriers to be stacked while maintaining acceptable matching losses and impedance stability.
3Quantity of substance
If conventional information carriers are stacked together, then the quantity of information carriers increases, but coupling effects among carriers make accurate reading difficult
Solution Approach 1:
The patent uses asymmetric offset of the annular segment's central axis relative to the carrying sheet's central axis. This creates intentional misalignment between stacked carriers that reduces electromagnetic field overlap and coupling effects, allowing multiple carriers to be stacked without significant interference between them.
Solution Approach 2:
The insulating protector serves as an intermediary layer between the carrying sheet and the tag antenna. This intermediate insulating structure helps isolate the antenna from the conductive carrying sheet, reducing unwanted coupling effects and improving antenna performance when carriers are stacked.
Data Source
AI summary
A tag antenna structure of an information carrier includes a carrying sheet and a tag antenna disposed on the carrying sheet. An outer lateral edge of the carrying sheet is symmetrical to a first central axis, and a distance between the outer lateral edge of the carrying sheet and the first central axis is defined as a first outer radius. The tag antenna includes an annular segment and two extending segments respectively extending from two end portions of the annular segment. An outer lateral edge of the annular segment is symmetrical to a second central axis, and a distance between the outer lateral edge of the annular segment and the second central axis is defined as a second outer radius that is smaller than the first outer radius. The second central axis and the first central axis have an offset distance there-between that is larger than zero.