RFID Antenna Narrow-Gap Structure for Microwaveable Food Packages
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Solution Overview
Problem
RFID tags used in microwaveable food packages face safety risks due to voltage build-up and potential arcing when exposed to microwave frequencies, leading to deformation, sparking, and fire hazards, and existing solutions like shielding layers complicate and increase production costs.
Innovation Solution
An RFID tag antenna design with a narrow gap of less than 80 µm, preferably less than 50 µm, and a wide gap width, or a bypass path, to create a low impedance path for microwave frequencies while maintaining UHF operation, reducing voltage build-up and preventing arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional RFID tag with a larger gap (100-200 μm) is used, then the RFID functionality operates normally at UHF frequencies, but voltage build-up occurs at microwave frequencies leading to safety risks such as arcing, deformation, and fire hazards
Solution Approach 1:
The patent changes the critical parameter of gap length from conventional 100-200 μm to less than 80 μm (preferably 10-50 μm). This parameter change creates a low impedance path at microwave frequencies that prevents voltage build-up and arcing, while maintaining RFID functionality at UHF frequencies through proper antenna design
Solution Approach 2:
The antenna structure is designed to exhibit different electrical characteristics at different frequencies. At UHF frequencies (860-960 MHz), the antenna maintains its normal RFID functionality. At microwave frequencies (2,450 MHz), the narrow gap creates a capacitive effect that provides a low impedance path, dynamically adapting the electrical behavior based on the operating frequency
2Object-affected harmful factors
If a shielding layer is added to prevent voltage build-up at microwave frequencies, then safety risks are reduced, but the production complexity and costs increase
Solution Approach 1:
The patent extracts and eliminates the need for complex shielding layers by directly modifying the antenna gap dimension. The solution is achieved through the antenna structure itself rather than adding separate shielding components, thereby reducing production complexity while maintaining safety
Solution Approach 2:
The patent combines the safety function (preventing microwave-induced voltage build-up) with the existing antenna structure by modifying the gap dimension. This merges the safety protection function into the antenna design itself, eliminating the need for separate shielding layers and reducing overall device complexity
3Object-affected harmful factors
If the gap is reduced to less than 80 μm to prevent arcing, then safety at microwave frequencies is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies a gap length parameter of less than 80 μm (preferably 10-50 μm) that balances safety requirements with manufacturability. This parameter range is sufficiently small to prevent arcing at microwave frequencies but large enough to be manufactured with standard precision capabilities
Solution Approach 2:
The patent applies different quality requirements to different parts of the antenna structure. The gap region requires high precision (less than 80 μm) to prevent arcing, while other parts of the antenna can be manufactured with standard tolerances. This localized quality approach minimizes overall manufacturing complexity while ensuring safety at the critical gap location
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 narrow gap design effectively reduces voltage build-up at microwave frequencies, ensuring safe operation without compromising RFID functionality, and simplifies production by reducing complexity and costs.
Implementation Method 1
The narrow gap design effectively reduces voltage build-up at microwave frequencies, ensuring safe operation without compromising RFID functionality
Implementation Method 2
The RFID tag antenna design with a narrow gap of less than 80 µm, preferably less than 50 µm, and a wide gap width, or a bypass path, to create a low impedance path for microwave frequencies while maintaining UHF operation
Data Source
Figure 1~5
Figure 6~7
Figure 8~10
AI summary
An antenna (1) for an RFID (Radio Frequency Identification) tag (100) comprises two antenna parts (11a, 11b) being arranged at opposite end areas of the antenna, and at least one intermediate part (12) forming a bridge between the antenna parts. One of the at least one intermediate part comprises power feeding areas (13a; 13b) to be connected to an integrated circuit (3). Further, a first gap (14; 14b) is arranged in one of the at least one intermediate part, and has a gap length of less than 80 μm, which forms a low impedance path for current at microwave frequencies.