RFID Antenna Structure for Mobile Device Integration
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Solution Overview
Problem
RFID tag devices experience significant performance degradation and reduced transmission distance when placed near a ground plane, such as a mobile device, due to attenuation effects, making them non-functional for applications like vehicular tolls where separation from the ground plane is unfeasible.
Innovation Solution
The design of an RFID tag device with a dipole structure and tuning loop antenna assembly that couples energy into a proximate mobile device, increasing antenna gain and minimizing signal attenuation, allowing for effective radio frequency transmission even in close proximity to a ground plane, and incorporating a near field communication (NFC) antenna to power the RFID tag using captured energy from the mobile device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an RFID tag is placed near a ground plane (mobile device), then the RFID tag can be integrated with the mobile device for convenient use, but the transmission distance and performance of the RFID tag are significantly degraded
Solution Approach 1:
A tuning loop antenna is introduced as an intermediary component between the RFID tag dipole antenna and the mobile device ground plane. The tuning loop couples energy into the mobile device while minimizing detuning effects, enabling the RFID tag to maintain extended transmission distance (20-100 feet) even when integrated with the mobile device.
2Reliability
If the RFID tag is separated from the ground plane by at least 6 mm, then the degradation effects are minimized, but direct coupling between the mobile device and RFID tag becomes unfeasible
Solution Approach 1:
The tuning loop antenna serves as a mediator that eliminates the need for physical separation. It couples electromagnetic energy from the RFID tag into the mobile device while preventing detuning, achieving both close integration and maintained transmission range without requiring 6 mm separation.
Solution Approach 2:
The patent changes the electromagnetic coupling parameters by introducing the tuning loop with specific inductance and geometry. This modifies the energy transfer mechanism from direct capacitive coupling (which causes detuning) to inductive coupling through the tuning loop, maintaining performance at zero separation distance.
3Adaptability or versatility
If a standard RFID tag is placed on the back of a mobile device, then the RFID tag is easily integrated and movable, but it becomes non-functional due to ground plane detuning effects
Solution Approach 1:
The tuning loop antenna acts as an intermediary that enables functionality despite direct contact with the ground plane. It couples energy into the mobile device while minimizing detuning effects, making the RFID tag functional when integrated with mobile devices without sacrificing movability between devices.
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 enhances the RFID tag's transmission range, enabling effective communication over distances of up to 20 to 100 feet, facilitating use in retail, tracking, and payment applications while allowing the RFID tag to be easily moved between devices, unlike conventional RFID tags.
Implementation Method 1
The design of an RFID tag device with a dipole structure and tuning loop antenna assembly that couples energy into a proximate mobile device, increasing antenna gain and minimizing signal attenuation
Implementation Method 2
incorporating a near field communication (NFC) antenna to power the RFID tag using captured energy from the mobile device
Data Source
AI summary
An RFID tag device with an RFID antenna assembly that increases transmission range of the RFID tag device when adhesively coupled to a mobile device. The RFID tag device includes a RF interface that operates at a first RF frequency, a controller coupled to the RF interfaces, and the RFID antenna assembly. The RFID antenna assembly includes a first and a second dipole elements, each shaped as a half rectangle with an additional segment joining the respective element to a tuning element. The RFID antenna also includes a tuning element, which is a loop antenna, connecting the RF interface to the controller. A structure of the RF antennal assembly, when the RFID tag device is coupled to a mobile device, causes the mobile device to function as a reflector to increase gain of the RFID antenna assembly thereby improving transmission range.