RFID Stripline Coupler for Selective Transponder Communication
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Solution Overview
Problem
RFID systems face challenges in selectively communicating with individual transponders among multiple adjacent ones, leading to collision errors and requiring complex collision management techniques or costly shielding, which are not feasible in space-restricted applications like RFID printer-encoders.
Innovation Solution
A spatially selective coupler with a conductive strip between two ground planes, configured to propagate electromagnetic fields perpendicular to its length, allowing controlled transmission to a targeted transponder without the need for anti-collision management or shielding, and optimized for compact designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If collision management techniques are used to allow near simultaneous communication between multiple transponders and a single transceiver, then communication capability is improved, but system complexity, cost, and response time increase
Solution Approach 1:
The invention segments the electromagnetic field interaction by using a coupler with a specific geometric configuration (conductive strip between two ground planes) that creates distinct field zones. This allows the system to physically separate the communication zones for different transponders, enabling selective interrogation without complex collision management protocols.
Solution Approach 2:
The coupler acts as an intermediary device between the transceiver and multiple transponders. By positioning the coupler in proximity to the transponders and using its specific structure, it mediates the electromagnetic field distribution to enable selective communication with individual transponders while preventing simultaneous activation of multiple transponders.
2Reliability
If RF-shielded housings are used to electrically isolate transponders from one another, then multiple transponder activation is prevented, but cost and system complexity increase
Solution Approach 1:
The invention replaces the mechanical/physical shielding approach (RF-shielded housings) with an electromagnetic field-based solution. The coupler's specific geometry and material properties are used to control and direct the electromagnetic fields, achieving transponder isolation through field manipulation rather than physical barriers.
3Reliability
If RF-shielded housings are used to shield adjacent transponders, then transponder isolation is achieved, but space and weight requirements increase
Solution Approach 1:
The invention substitutes heavy physical shielding structures with a lightweight coupler device that achieves the same isolation effect through electromagnetic field control. The coupler's compact design and use of conductive materials with specific geometric configuration provide the necessary field management without the weight penalty of RF-shielded housings.
4Reliability
If RF-shielded housings are used to prevent multiple transponder activation, then communication reliability is improved, but cost increases
Solution Approach 1:
The invention uses a cost-effective coupler design that can be manufactured using standard PCB techniques and conductive materials. Rather than expensive RF-shielded housings, the coupler employs a simple but effective geometric configuration that achieves the desired isolation effect at lower cost.
5Area of stationary object
If the coupler length is reduced to one-half wavelength or less, then footprint is minimized for space-restricted systems, but transmission range must be precisely controlled
Solution Approach 1:
The invention optimizes the coupler dimensions, specifically setting the length to one-half wavelength or less of the operating frequency, and adjusts the width and spacing parameters to achieve the desired field distribution. This parameter optimization enables compact footprint while maintaining controlled transmission characteristics.
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 selective communication with individual transponders, minimizing inadvertent activation and reducing system complexity and cost, while maintaining a compact footprint suitable for space-restricted environments.
Implementation Method 1
a conductive strip being positioned at least partially between the first and second ground planes and configured to propagate a plurality of electromagnetic fields
Data Source
AI summary
A stripline coupler for a RFID system is provided. The coupler is configured to communicate with a targeted transponder from among a group of multiple adjacent transponders. The coupler may include a conductive strip, a terminating load, a dielectric material, a first ground plane, and a second ground plane. The conductive strip extends between the first and second ground planes and the dielectric material from an input end connected to a transceiver to a loaded end connected to the terminating load. The conductive strip may be configured to propagate electromagnetic fields concentrated in a near field region of the conductive strip in a direction generally perpendicular to the conductive strip to couple with a targeted transponder. The coupler may include an enclosure for directing the electromagnetic fields. The conductive strip may have a tapered or non-linear profile such as a modified bow-tie profile, an exponential profile, or a Klopfenstein profile.