Passive Frequency Selective Surface Tags for Wireless Object Tracking
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Solution Overview
Problem
Current inventory tracking solutions, such as barcodes and RFID, are either simplistic and prone to errors or costly and complex, failing to provide maximum efficiency and detailed data, while also being limited by their interaction with transmitter and tag systems, and there is a need for technologies that leverage wireless networks for object detection and tracking.
Innovation Solution
The use of passive frequency selective surface (FSS) tags that interact with existing wireless signals like WiFi, 4G, and 5G, without the need for integrated circuits or batteries, allowing for low-cost, high-accuracy tracking and identification by producing unique responses to wireless signals, which can be decoded using existing network infrastructure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RFID tags are used for tracking, then detection accuracy and durability are improved, but cost and device complexity increase significantly
Solution Approach 1:
The patent extracts the essential identification function from complex RFID systems by removing integrated circuits, batteries, and power management components. Only the passive resonant elements (FSS structures) are retained, which interact with electromagnetic fields to provide unique identification signatures without requiring active electronics or power sources.
Solution Approach 2:
The patent employs inexpensive passive FSS tags that can be manufactured at low cost using simple conductive materials and printing techniques. These tags are designed to be disposable or single-use identification elements that provide sufficient functionality without the need for durable, expensive RFID components.
2Reliability
If RFID tags are used for tracking, then detection through objects is improved, but cost per tag increases
Solution Approach 1:
The patent replaces the mechanical/electronic RFID tag system with an electromagnetic resonance-based FSS tag system. The conductive FSS structures resonate at specific frequencies when exposed to electromagnetic fields, providing detection capability through objects without requiring complex electronics, batteries, or ICs, thereby significantly reducing manufacturing cost.
3Ease of manufacture
If barcode systems are used for tracking, then cost-effectiveness is improved, but detection reliability and accuracy deteriorate due to line of sight requirements
Solution Approach 1:
The patent replaces optical barcode scanning with electromagnetic field-based FSS tag detection. The FSS tags resonate with electromagnetic waves at unique frequencies, allowing detection through non-line-of-sight conditions, penetration through certain materials, and automated reading without the need for direct visual contact, thereby maintaining cost-effectiveness while improving detection reliability.
4Productivity
If traditional RFID systems are used, then multiple detection capability is improved, but infrastructure complexity and cost increase
Solution Approach 1:
The patent makes existing wireless infrastructure (WiFi routers, cellular base stations, Bluetooth devices) multi-functional by enabling them to serve both their primary communication purposes and as transmitters for FSS tag detection. This eliminates the need for dedicated RFID readers and infrastructure, reducing complexity while maintaining multiple detection capability across the network.
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
This approach enables cost-effective, accurate, and efficient tracking and identification of objects, allowing for 'cradle-to-grave' usage without the drawbacks of traditional systems, with the ability to handle a large number of unique labels and provide detailed data, while being simple to set up and use, leveraging the widespread availability of wireless networks.
Implementation Method 1
The passive FSS based tags are tuned (e.g., by the geometry of their metallic structures) to interact with existing wireless signals used with network standards such as WiFi, 4G, and 5G
Implementation Method 2
A frequency selective surface (FSS) is an electromagnetic structure (or combination of structures) that resonates with a particular frequency
Data Source
AI summary
Embodiments of the invention employ frequency selective surfaces that resonate at defined frequencies depending on geometry. Tag-based embodiments allow the ability to have passive, battery-free, systems that can be used for applications including but not limited to inventory tracking, locating, and indoor radar (e.g. determining whether something labeled with a tag is in range of a particular wireless network signal). The shape of the resonator, among other available factors, influences the interference frequency. Embodiments may include metal based tags on a non-conductive material that will be used to disturb, for example, frequencies from 3 KHz to 300 GHz. These disturbances at specific resonant frequencies are useable to, for example, locate the tags/labels using WiFi Mapping, sending a WiFi signal and getting unique feedback on a router.