Passive RFID Sensor Impedance Tuning for Power Loss
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Solution Overview
Problem
Passive RFID systems face challenges in matching the resonant frequency of their antennas with the carrier frequency of RF signals due to the lack of standards in RFID system frequencies and the broad frequency spectrum, leading to power loss and inefficiency, especially in applications where variable impedance circuits with broad tuning ranges are needed.
Innovation Solution
The implementation of an RF-based environmental sensing system with a special antenna arrangement and an RF transceiver that includes a tank circuit with a selectively variable impedance, allowing for dynamic adjustment of the impedance to match the modified antenna impedance and sense environmental conditions, such as temperature, humidity, or proximity, by varying the reactive component impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single antenna structure is used to receive RF signals, then the system structure is simple, but the resonant frequency of the antenna cannot be matched with the carrier frequency of RF signals, leading to power loss
Solution Approach 1:
The patent applies dynamics by making the antenna impedance variable rather than fixed. The antenna structure includes variable impedance elements that can be dynamically adjusted to match different carrier frequencies, enabling the system to adapt to varying RF signal frequencies and minimize power loss across different operating conditions.
Solution Approach 2:
The patent changes the impedance parameter of the antenna from a fixed value to a variable value. By incorporating variable impedance circuits and adjustable reactive components, the antenna can modify its electrical characteristics to match the carrier frequency of incoming RF signals, thereby resolving the frequency mismatch problem without requiring multiple fixed antenna structures.
2Adaptability or versatility
If a variable impedance circuit with broad tuning range is implemented, then frequency matching is improved, but the device complexity increases
Solution Approach 1:
The patent implements a variable impedance circuit that serves multiple functions: it acts as both an impedance matching network and a frequency tuning mechanism. This multi-functional design allows a single circuit structure to provide broad frequency adaptability while avoiding the need for separate dedicated circuits for each function, thereby reducing overall system complexity.
Solution Approach 2:
The system incorporates automatic frequency matching capabilities where the variable impedance circuit can self-adjust to match the carrier frequency of incoming RF signals. This self-tuning mechanism reduces the need for complex manual adjustment mechanisms and external control systems, achieving broad frequency adaptability with minimized additional complexity.
3Use of energy by moving object
If the resonant frequency of the antenna is matched with the carrier frequency, then power transfer efficiency is improved, but the system requires complex impedance matching circuits
Solution Approach 1:
The patent merges the antenna structure with the impedance matching functionality by integrating variable impedance elements directly into the antenna design. This combination eliminates the need for separate complex impedance matching circuits, as the antenna itself provides the matching capability through its variable impedance characteristics, thereby improving power transfer efficiency without proportionally increasing system complexity.
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 solution enables efficient power transfer and effective sensing of environmental conditions by dynamically matching the resonant frequency of the tank circuit to the carrier frequency, enhancing the performance of passive RFID systems across various frequency ranges.
Implementation Method 1
dynamically varying the impedance of the tank circuit substantially to match the modified antenna impedance
Implementation Method 2
dynamically matching the resonant frequency of the tank circuit to the carrier frequency
Implementation Method 3
a transmission line operatively coupled to the antenna and adapted selectively to modify the antenna impendence
Data Source
AI summary
A method includes varying, by a tuning module of a passive radio RFID sensor, a reactive component impedance coupled to the tuning module and an antenna of the passive RFID sensor in order to change a system impedance. The method further includes producing an impedance value representative of the reactive component's impedance. The method further includes storing, by a memory module of the passive RFID sensor, the impedance value, identification information corresponding to the antenna, and a timestamp corresponding to the impedance value. The method further includes communicating, by a wireless communication module of the passive RFID sensor, the impedance value, the identification information, and the timestamp to an RFID reader. When the impedance value, the identification information, and the timestamp indicate an unfavorable environmental condition, the method further includes generating, by the RFID reader, an alarm signal.