RFID Antenna Array Beamforming for Inhomogeneous Media
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Solution Overview
Problem
The widespread adoption of battery-less RFID technology is hindered by poor performance in environments with materials that adversely affect RF propagation, such as metal, dielectrics, and lossy dielectrics, which require higher RF electromagnetic field strengths for operation, and existing antenna array technologies lack sufficient degrees of freedom to effectively mitigate these issues.
Innovation Solution
An antenna array system with an array controller and control algorithms that independently control transfer functions between a common RF input/output port and multiple antenna elements, utilizing phase and amplitude adjustments to optimize RF excitation in inhomogeneous media, such as warehouses or pallets, without prior knowledge of propagation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If battery-less RFID tags are used to reduce cost and extend shelf life, then manufacturing cost and storage duration are improved, but RF field strength requirement increases making operation difficult in adverse environments
Solution Approach 1:
The patent applies dynamic beamforming by continuously adjusting the phase and amplitude of signals across multiple antenna elements in real-time. This dynamic adaptation allows the system to maintain optimal RF field strength at tag locations despite changes in environment, material interactions, or tag positions, thereby enabling reliable operation of battery-less tags without requiring excessive transmitted power
Solution Approach 2:
The system changes multiple parameters simultaneously including phase shifts, amplitude weights, and beam directions across the antenna array. By optimizing these parameters dynamically, the system concentrates RF energy precisely where needed to power battery-less tags, overcoming the power deficiency issue while maintaining cost-effectiveness
2Device complexity
If traditional antenna arrays are used with limited degrees of freedom, then device complexity is reduced, but ability to mitigate adverse RF propagation effects deteriorates
Solution Approach 1:
The patent implements dynamic adaptation of beamforming weights and phases in response to real-time channel conditions. This allows the system to actively compensate for adverse propagation effects such as multipath fading, shadowing, and material interactions, significantly improving reliability in challenging environments without requiring overly complex static structures
Solution Approach 2:
The system employs feedback mechanisms where channel state information is continuously monitored and used to adjust antenna element excitations. This closed-loop control enables the system to adapt to changing environmental conditions and maintain reliable communication with battery-less tags even in the presence of adverse RF propagation effects
3Reliability
If higher RF electromagnetic field strength is transmitted to power battery-less tags in adverse environments, then tag operation reliability is improved, but regulatory constraints on radiated RF power levels are violated
Solution Approach 1:
The patent applies local quality enhancement by concentrating RF energy precisely at the location of each battery-less tag through spatial beamforming. Instead of uniformly increasing transmitted power across all directions, the system creates localized high-field regions only where tags are present, thereby improving tag operation reliability without exceeding regulatory power limits in other areas
Solution Approach 2:
The antenna array is segmented into multiple independently controllable elements, each contributing to the overall field distribution. By independently adjusting the phase and amplitude of each element, the system can create focused beams that deliver sufficient power to tags locally while maintaining compliance with regulatory constraints on total radiated power
4Adaptability or versatility
If materials such as metal, dielectrics, and lossy dielectrics are present in the environment, then application versatility is improved, but RF coupling between reader and tag deteriorates
Solution Approach 1:
The system dynamically adjusts beamforming parameters to compensate for the presence of various materials in the environment. By continuously adapting to changing propagation conditions caused by metal, dielectrics, and lossy materials, the system maintains reliable RF coupling across diverse application scenarios, thereby preserving both versatility and reliability
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 system achieves sufficient RF field strength and enhances performance in adverse propagation environments, enabling effective reading of battery-less RFID tags by optimizing antenna element settings to maximize induced voltage at the tag terminals within the constraints of available power.
Implementation Method 1
The incident RF field level required to provide operating power for the electronic circuitry is far greater than that required to communicate with already-powered circuits
Data Source
AI summary
Embodiments of the invention pertain to Radio Frequency Identification (RFID) method and system using an antenna array, an array controller, and control algorithms. Embodiments of the invention can induce strong radio-frequency (RF) excitation, for a given level of radiated RF power, at any point within an arbitrary inhomogeneous medium. For RFID applications, one typical inhomogeneous medium is an ensemble of cases on a pallet. Another typical medium is a warehouse environment having stored goods together with shelving and other material present. An embodiment of the invention is applicable to the process of reading battery-less, or “passive” RFID tags, which rely on incident RF electromagnetic fields established by RFID readers to power the electronic circuitry within the tags.