Flat Loop Antenna for Metal-Resistant RFID
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Solution Overview
Problem
RFID communication devices with coil antennas face challenges in size constraints and frequency stability due to metal components obstructing the induction field, leading to reduced communication distance and unsatisfactory performance.
Innovation Solution
A radio communication device featuring a flat radiation element with a loop and a coil pattern connected in series, where the coil pattern and loop are coupled via a magnetic field, allowing for intensified induction fields and stable frequency characteristics, independent of nearby metal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coil antenna is used in an HF RFID system, then communication functionality is achieved, but the antenna size becomes large and requires significant space in the device casing
Solution Approach 1:
The patent transitions from a traditional three-dimensional coil antenna structure to a planar flat radiation element with a loop structure. This dimensional change allows the antenna to be integrated into the flat casing of mobile terminals without requiring significant volume, while maintaining RFID communication functionality through magnetic field coupling between the loop and external reader-writer antennas.
2Adaptability or versatility
If metal components are included in the device casing, then device functionality is enhanced, but the metal parts obstruct the induction field at the coil antenna and change its resonant frequency
Solution Approach 1:
The patent extracts the antenna structure from the traditional coil form that is sensitive to metal interference and replaces it with a flat loop radiation element. This extracted and reconfigured structure reduces the harmful interaction with metal components in the device casing, maintaining frequency characteristic stability while allowing metal parts to remain in the device for other functional purposes.
3Volume of moving object
If the coil antenna size is reduced to fit in compact devices, then device compactness is improved, but communication distance and signal strength are compromised
Solution Approach 1:
The patent merges the radiation function across the entire flat loop structure, where the whole loop acts as the radiating element rather than a small coil. This distributed radiation approach allows compact dimensions while maintaining adequate communication distance, as the extended planar structure provides sufficient electromagnetic coupling area with external readers.
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 enables a compact RFID device with extended communication distance and stable frequency performance, minimizing interference from metal components and optimizing signal radiation across the entire surface.
Implementation Method 1
the first coil pattern and the loop are connected in series and are coupled via a magnetic field
Implementation Method 2
an induction field generated at the first coil pattern and an induction field generated at the loop are intensified by each other
Data Source
AI summary
A radio communication device includes a flat radiation element including a loop with a first end and a second end; a feed element including a coil pattern connected to the first end of the loop; and a radio IC element connected to the coil pattern. The coil pattern is disposed near the loop and is wound such that an electric power supply to the coil pattern generates a current flow in the coil pattern and a current flow in the loop in a same direction. The coil pattern and the loop are connected in series and are coupled via a magnetic field.