Planar Flexible UWB Tag with Balun-Free Differential Antenna
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Solution Overview
Problem
Existing UWB RF tracking tags are obtrusive, fragile, and have reduced performance due to their rigid 3D structure, requiring a balun device that causes loss and increased power consumption, making them unsuitable for use in athletic environments.
Innovation Solution
A planar flexible RF tag with complementary antenna patches and a non-electrically-conductive substrate, allowing direct differential connection to the RF transceiver without a balun, and capable of capacitive charging without electrical contact, using a flexible rechargeable battery and optimized geometry for transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a 3D antenna structure is used to generate the necessary propagation pattern, then the RF tracking tag achieves sufficient transmission range and pattern coverage, but the tag size and weight increase making it obtrusive for athletic equipment
Solution Approach 1:
The patent transitions from a conventional 3D antenna structure to a planar 2D antenna design. The antenna elements are arranged in a flat configuration on a substrate, eliminating the need for three-dimensional spatial arrangement while maintaining the required propagation pattern through optimized planar geometry and element positioning.
Solution Approach 2:
The patent extracts and removes the balun component from the RF tag system. By designing the antenna with direct differential feed points, the balanced-to-unbalanced converter is eliminated, reducing component count, size, and weight while avoiding the losses associated with balun transformations.
2Strength
If a rigid enclosure is used to protect the antenna and electronics, then the RF tag gains mechanical protection, but it becomes fragile when exposed to bending forces
Solution Approach 1:
The patent replaces rigid enclosures with flexible packaging materials that can accommodate bending and deformation. The antenna and electronics are mounted on flexible substrates and enclosed in flexible protective layers, allowing the entire assembly to flex without breaking while maintaining mechanical protection.
3Adaptability or versatility
If a balun device is used to convert balanced to unbalanced RF currents, then the RF tag can interface with traditional microwave patch antennas, but power loss increases and operational range decreases
Solution Approach 1:
The patent removes the balun device from the system by designing the antenna with direct differential feed points that interface naturally with balanced RF transceiver outputs. This eliminates the need for balanced-to-unbalanced conversion and the associated power losses.
4Device complexity
If traditional microwave patch antennas are used with single-ended drive, then the antenna structure is simple, but the propagation pattern is unidirectionally biased making it unsuitable for RF tracking
Solution Approach 1:
The patent employs symmetric antenna element arrangements fed by differential signals to achieve omnidirectional or controlled bidirectional propagation patterns. The symmetric geometry with differential excitation creates balanced radiation patterns suitable for three-dimensional tracking applications.
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 provides a thin, flexible, and robust RF tag with improved performance and range, capable of unobtrusive integration into athletic equipment and clothing, with efficient capacitive charging and reduced fragility.
Implementation Method 1
an antenna with three-dimensional (3D) geometry and a battery of sufficient power to meet the transmission needs
Implementation Method 2
capable of capacitive charging without electrical contact
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A planar flexible ultra-wideband (UWB) RF antenna includes a flexible non-electrically-conductive substrate and at least one antenna patch having electrically conductive metal positioned on one side of the flexible non-electrically-conductive substrate and having geometry defining a wirelessly transmitted UWB signal. The antenna may electrically couple with an RF transmitter circuit formed on a second side of the flexible substrate and controlled by a microcontroller circuit, formed on the second side, to transmit a radio signal. The RF tag may include at least one decoupling circuit directly electrically connected to the RF antenna and having a decoupling frequency that is different from a transmitting frequency of the antenna. The decoupling circuit transferring power from the antenna when the antenna receives capacitive power from an external non-electrical contact charger operating at the decoupling frequency and having at least one plate of similar geometry to the at least one antenna patch.