Folded RFID Antenna Structure for Confined-Space Tag Reading
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Solution Overview
Problem
Conventional RFID antennas are rigid and long, making them unsuitable for incorporation into confined spaces such as cabinets or doorways, where a flexible and compact design is required without compromising performance.
Innovation Solution
The antenna is constructed using flexible feed lines and dipoles mounted on a resilient Mylar film, allowing for folding without performance degradation, with non-overlapping stubs between layers and a plastic foam spacer to prevent coupling, enabling a compact sandwich structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a rigid, long antenna is used, then antenna performance is maintained, but the antenna cannot be accommodated in confined spaces such as cabinets or doorways
Solution Approach 1:
The patent applies this principle by mounting the antenna transmission lines and dipoles on a flexible film substrate instead of a rigid board. This allows the antenna to be folded and distorted from a single plane while maintaining electrical performance, enabling adaptation to confined spaces like cabinets and doorways without compromising the antenna's functional integrity
Solution Approach 2:
The patent applies this principle by transitioning the antenna from a planar two-dimensional configuration to a three-dimensional folded structure. The antenna can be folded back on itself or distorted out of plane, utilizing the third dimension to achieve compact form factors while maintaining the necessary electrical length and performance characteristics
2Adaptability or versatility
If the antenna is folded to fit confined spaces, then adaptability to environments is improved, but performance may be degraded due to layer overlap and signal coupling
Solution Approach 1:
The patent applies this principle by introducing a foam spacer as an intermediary element between the folded layers of the antenna. This foam spacer physically separates the layers and prevents electromagnetic coupling between them, thereby maintaining antenna performance while allowing the folded configuration necessary for adaptation to confined spaces
Solution Approach 2:
The patent applies this principle by folding the antenna back on itself in a nested configuration. The transmission lines and dipoles are arranged so that folded layers are stacked one within another, creating a compact sandwich structure that fits confined spaces while the foam spacer ensures proper spacing to prevent performance degradation
Data Source
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Figure 5
AI summary
An RFID antenna having two flexible elongated conductive transmission lines with coplanar RFID energy radiation perturbations distributed along the transmission lines, the transmission lines and perturbations being folded between ends of the transmission lines so that the transmission lines of one fold overlie and are adjacent the transmission lines of the other fold and an electrically insulating layer disposed between lengths of the transmission lines on either side of the fold.