Chipless RFID Tag Impedance Encoding for Data Density
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Solution Overview
Problem
Chipless RFID tags face challenges in efficient data encoding and transmission, as they can only provide a small amount of data per bit, leading to increased tag dimensions and interference, making them less effective and costly.
Innovation Solution
The use of electrical impedance variations in antenna portions, such as dipole, resonator, and meander line loaded antennas, to encode and transmit data through backscattered RF signals, allowing multiple digital bits to be represented by a single symbol, reducing the number of required coding frequencies and tag dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If chipless RFID tags use time-domain reflectometry or frequency signature techniques to encode data, then data transmission is achieved, but the amount of data per bit is limited and tag dimension increases
Solution Approach 1:
The patent changes the encoding parameter from time-domain or frequency-domain to impedance-domain. By varying the electrical impedance of antenna portions (through geometry, material, or structure), multiple bits are encoded in a single backscattered signal, increasing data transmission efficiency while reducing the number of required frequencies and tag dimensions
Solution Approach 2:
The patent makes each antenna portion multi-functional by encoding multiple bits through impedance variation. A single antenna portion can represent multiple digital bits by adjusting its impedance characteristics, eliminating the need for separate echoes or frequency components for each bit, thus reducing tag complexity and size
2Loss of information
If the number of echoes and signature frequencies is multiplied to increase data capacity, then more data can be transmitted, but intra-echoes or frequencies interferences decrease data discrimination
Solution Approach 1:
The patent transitions from using multiple frequencies or time-echoes to using impedance variation as the encoding parameter. This single-parameter approach (impedance) avoids the interference problems of multiple frequencies while still enabling high data capacity through multi-bit encoding per signal
Solution Approach 2:
The patent extracts the essential encoding function from multiple interfering components (multiple echoes, multiple frequency signatures) and concentrates it into a single impedance parameter per antenna portion. This removes the harmful interferences while preserving the data encoding capability
3Loss of information
If chipless RFID tags use multiple coding frequencies to increase data transmission, then data capacity improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent simplifies the device by changing the encoding mechanism from multiple frequency components to impedance variation. This reduces the number of required coding frequencies and simplifies the antenna structure, making the tag easier to manufacture with lower complexity
Solution Approach 2:
The patent creates multi-functional antenna portions that can encode multiple bits through impedance control. This universal encoding approach eliminates the need for multiple dedicated frequency components, reducing device complexity while maintaining high data transmission capacity
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 efficient and cost-effective data encoding and transmission, allowing for a unique identifier or message to be transmitted with reduced tag complexity and manufacturing costs, while maintaining data discrimination.
Implementation Method 1
the code is defined by the electrical impedance of portions of antennas or electrically connected to one or more antennas
Implementation Method 2
transmitting a message from a (chipless) device to a reader as a RF backscattered radiation in response to an impinging RF signal
Data Source
AI summary
An RFID tag (1) is configured to transmit a predetermined code (3K) as a RF backscattered radiation (2) in response to an impinging RF signal (41). The RFID tag (1) is configured to react to an impinging signal at a predetermined reference frequency (23) with a reference backscattered signal (2R). The RFID tag (1) is also configured and to react to an impinging signal (41) at any of a group of transmission frequencies (21, 22) with coding backscattered signals (2F-G) whose amplitudes (20A, 20B) relative to the amplitude (20R) of the reference backscattered signal define the code (3K). An RFID reader (4), a kit (5) and a method for transmitting a message from a device (1) to a reader (4) as a RF backscattered radiation (2) in response to an impinging RF signal (41).