RFID Tag Antenna Line Length for Microwave Safety
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Solution Overview
Problem
RFID tags attached to food products can ignite or catch fire when heated in a microwave oven due to resonance and discharge caused by electromagnetic waves, posing a risk of combustion.
Innovation Solution
A wireless communication device with an antenna pattern composed of conductor patterns that do not resonate at microwave frequencies, preventing heat generation and discharge, and using a flame-retardant base material to prevent ignition and deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional RFID tag with metal antenna pattern is used, then communication function is achieved, but ignition and combustion occur during microwave heating
Solution Approach 1:
The antenna pattern's line length is specifically designed to avoid resonance at microwave frequencies (2.45 GHz). By changing the dimensional parameter of the antenna from conventional lengths to non-resonant lengths, the harmful resonance effect during microwave heating is eliminated while maintaining UHF band communication functionality
Solution Approach 2:
The RFID tag uses a composite structure combining flame-retardant base material with a specifically designed non-resonant antenna pattern. This composite approach addresses both the communication requirement and the safety requirement by integrating materials and design features that prevent ignition
2Object-affected harmful factors
If flame-retardant base material is used, then combustion prevention is improved, but metal antenna portion still causes discharge and heat generation
Solution Approach 1:
The line length of the metal antenna pattern is specifically controlled to be non-resonant at microwave frequencies. This parameter change prevents the metal portion from generating excessive heat or discharge during microwave heating, eliminating the harmful effects while maintaining the flame-retardant base material's protection
3Productivity
If microwave heating is applied to heated food, then heating efficiency is improved, but RFID tag resonance causes safety hazards
Solution Approach 1:
The antenna pattern's dimensional parameters are optimized to create a frequency separation between the communication band (UHF) and the microwave heating band (2.45 GHz). This allows microwave heating to proceed efficiently without causing resonance in the antenna, ensuring both productivity and safety
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
The solution effectively prevents ignition and combustion of RFID tags attached to food products during microwave heating, ensuring safety and maintaining the integrity of the product and device.
Implementation Method 1
each having a line length that does not cause resonance at a frequency in a microwave band for electromagnetic wave heating
Implementation Method 2
energy of electromagnetic waves from the microwave oven is absorbed by the RFID tag together with the product
Implementation Method 3
heat generation and sublimation of the metal material due to overcurrent flowing through the metal material portion
Data Source
AI summary
An RFID tag is providing for transmitting and receiving a communication signal. The RFID tag includes a base material, antenna patterns formed on the base material, and an RFIC package connected to the antenna patterns. The antenna patterns are defined by conductor patterns. The whole of the antenna patterns resonate at a communication frequency, and each of the plurality of conductor patterns has a line length that does not cause resonance at a frequency in a microwave band for electromagnetic wave heating higher than the communication frequency.