Chipless RFID Tag Distance Measurement Using Antenna Mode Signal Isolation
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Solution Overview
Problem
Current chipless RFID distance measurement methods are affected by noise, antenna-mode signals, and excitation signal waveforms, leading to inaccuracies, with the interference distance measurement method being more stable but requiring a reference plane and lacking calibration for delay generated by the reader and antenna.
Innovation Solution
An automatic search method for structural mode signals in chipless RFID tags using an ultra-wideband pulse signal, Fast Fourier transforms, and linear regression to isolate and refine distance measurements, reducing the influence of antenna-mode signals and improving accuracy through iterative window adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interference distance measurement method is used to improve stability and avoid calibration, then measurement stability is improved, but the requirement for a reference plane increases device complexity
Solution Approach 1:
The patent extracts and removes the reference plane component from the measurement system. By using the reader antenna's own reflected signal instead of a separate reference plane, the system eliminates the need for additional reference structures while maintaining the interference-based measurement stability.
Solution Approach 2:
The reader antenna serves multiple functions: it acts as both the transmitting antenna for the excitation signal and the reference signal source through its own reflected signal. This multi-functionality eliminates the need for dedicated reference plane structures while maintaining measurement stability.
2Device complexity
If the maximum value detection method or NFMPM is used to simplify the measurement process, then device complexity is reduced, but measurement precision deteriorates due to excitation signal waveform dependence
Solution Approach 1:
The patent converts the harmful effect of excitation signal waveform variations into a beneficial feature. By using the reader antenna's reflected signal as the reference, the system makes the measurement process inherently immune to excitation signal waveform changes, as both the measurement signal and reference signal are affected equally by waveform variations.
3Object-affected harmful factors
If traditional distance measurement methods are used to reduce noise impact, then noise resistance is improved, but the influence of antenna-mode signals increases measurement error
Solution Approach 1:
The patent implements a feedback mechanism where the reader antenna's reflected signal serves as a real-time reference that automatically compensates for antenna-mode signal variations. This feedback approach allows the system to dynamically adjust for antenna-mode signal effects without requiring separate noise filtering processes.
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 method enhances the accuracy of distance measurement by isolating structural mode signals, reducing noise interference, and stabilizing the interference distance measurement method, enabling precise positioning of chipless RFID tags.
Implementation Method 1
The reader generates an ultra-wideband pulse signal, the ultra-wideband pulse signal is radiated from the reader antenna to the space
Implementation Method 2
the interference distance measurement method is based on the principle of electromagnetic wave interference
Data Source
AI summary
The proposed invention discloses an automatic search method for a structural mode signal of a chipless RFID tag. A reference plane, a target to be tested, a reader antenna and a reader are set in space. The target to be tested is located within the reading range of the reader antenna. The distance difference between the tag and the reference plane, to the antenna, is measured by using the phenomenon of the backscattered signals of the tag and the reference plane interfering in space, to obtain the distance between the tag and the antenna. The time period for extracting the antenna mode of the tag may maximize the use of the antenna mode signal, thereby enhancing the accuracy of reading the tag.