Tilted RFID Antenna Design for Mobile Terminals
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Solution Overview
Problem
RFID antenna devices in communication terminal devices face challenges in orientation and directivity due to space restrictions and interference with other antennas, particularly in cellular phone terminals, leading to reduced antenna gain and communication efficiency.
Innovation Solution
A communication terminal device design featuring a tilted RFID antenna with a magnetic core and coil conductor positioned closer to the trailing end, separated from cellular phone antennas by a metal portion, allowing for independent operation and minimal interference, with specific size ratios for the magnetic core and coil conductor to optimize performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RFID antenna is arranged in the leading end portion of the casing, then communication performance is improved, but it interferes with cellular phone antenna characteristics
Solution Approach 1:
The patent positions the RFID antenna in the trailing end portion of the casing along the longitudinal axis, utilizing the unused space at the opposite end from the cellular phone antenna. This spatial reconfiguration in one dimension (longitudinal position) resolves the interference issue while maintaining RFID functionality through the tilted orientation that directs radiation toward the leading end.
Solution Approach 2:
The patent employs an asymmetric coil winding structure where the winding interval varies around the magnetic core, with tighter winding at certain positions and looser winding at others. This asymmetric configuration creates directional magnetic flux distribution that tilts the radiation pattern toward the leading end, enabling the trailing end placement to achieve leading end communication performance.
2Object-generated harmful factors
If the RFID antenna is spaced away from the cellular phone antenna, then interference is reduced, but the layout becomes difficult due to terminal size constraints
Solution Approach 1:
The patent utilizes the longitudinal dimension of the casing by placing the RFID antenna at the trailing end, opposite to the cellular phone antenna's leading end position. This one-dimensional spatial separation maximizes the use of available terminal space without requiring additional lateral or vertical space, effectively resolving the layout constraint while maintaining antenna isolation.
3Area of stationary object
If the RFID antenna is arranged in the trailing end portion, then layout flexibility is improved, but antenna gain during use is reduced
Solution Approach 1:
The patent implements asymmetric coil winding with varying winding intervals around the magnetic core. This creates an asymmetric magnetic field distribution that tilts the radiation pattern toward the leading end direction, compensating for the trailing end placement and restoring antenna gain during typical usage when the leading end is oriented toward the reader/writer.
Solution Approach 2:
The patent modifies the physical parameters of the coil structure by adjusting the winding interval at different positions around the magnetic core. This parameter change in the coil geometry directly alters the magnetic flux distribution and radiation pattern, enabling the trailing end antenna to achieve optimal gain in the required direction.
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
Enables effective communication at short distances without layout or directivity restrictions, maintaining antenna characteristics of both RFID and cellular phone antennas, even when the RFID antenna is not in the leading end portion of the casing.
Implementation Method 1
an antenna that includes a magnetic core (10) and a coil conductor (40)
Implementation Method 2
a magnetic core (10) that includes a first main surface and a second main surface
Data Source
AI summary
An RFID antenna is arranged in the vicinity of a metal portion of and on an outer surface side of a casing of a communication terminal device. The RFID antenna includes a magnetic core, and a coil conductor that is wound around the magnetic core. The coil conductor includes a first conductor portion positioned on a first main surface side of the magnetic core and a second conductor portion positioned on the second main surface side of the magnetic core and arranged at a different position than the first conductor portion when viewed in plan from the direction of the first and second main surfaces, and the coil conductor is arranged such that the first main surface side of the magnetic core is on the metal portion side and such that the first conductor portion of the coil conductor faces a leading end portion of the casing.