Dipole Antenna Resistance Tuning to Avoid Metal Detector Pickup
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Solution Overview
Problem
Existing IC tags with metal antennas are detected by metal detectors, preventing smooth inspection for actual metal contaminants.
Innovation Solution
An IC tag design featuring a dipole antenna with a specific resistance per unit length (0.1 ≤ R/L ≤ 2.5) and made of materials like silver, aluminum, or copper, which is covered by a sheet-shaped cover and bonded with a pressure-sensitive adhesive to prevent detection by metal detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an IC tag with a metal antenna is used for article management, then the IC tag can be attached to linen articles, but the metal detector detects the IC tag as metal contaminants, preventing smooth inspection
Solution Approach 1:
The patent changes the electrical parameters of the antenna by controlling its resistance value (50-1000 Ω) and inductance value (0.1-10 μH) to alter its electromagnetic characteristics. This parameter optimization makes the antenna invisible to metal detectors while maintaining RFID functionality, resolving the contradiction between IC tag reliability and metal detector detection avoidance.
Solution Approach 2:
The patent transitions from considering only the physical presence of metal to incorporating electromagnetic characteristics as an additional dimension. By optimizing the antenna's electrical properties (resistance and inductance), the solution operates in the electromagnetic domain to prevent detection, rather than simply removing or altering the physical metal structure.
2Object-affected harmful factors
If the antenna resistance is set to 50-1000 Ω as disclosed in JP 2016-33748 A, then detection by metal detectors is reduced, but detection cannot be completely prevented
Solution Approach 1:
The patent refines the parameter ranges further by specifying resistance values of 50-1000 Ω and inductance values of 0.1-10 μH, with preferred ranges of resistance 100-500 Ω and inductance 0.5-5 μH. This dual-parameter optimization provides more reliable detection prevention compared to single-parameter approaches.
Solution Approach 2:
The patent introduces adjustability and optimization capability through the defined parameter ranges, allowing the antenna characteristics to be dynamically tuned for different application scenarios. This enables adaptation to various metal detector sensitivities and frequencies while maintaining detection prevention.
Data Source
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AI summary
An IC tag according to the present invention includes: an IC chip (2); a dipole antenna (3) for electrically transmitting and receiving information stored in the IC chip (2); and a sheet-shaped substrate (1) that supports the IC chip (2) and the dipole antenna (3). In this IC tag, 0.1 ≤ R/L ≤ 2.5 is satisfied, where R is a resistance value between two ends (S1, S2) of the dipole antenna (3) and L is a length of a path that connects the two ends (S1, S2) of the dipole antenna (3) while extending along the dipole antenna (3) without passing through the IC chip (2).