Flexible Wearable Data Transceiver with Capacitive Antenna Coupling
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Solution Overview
Problem
RFID systems face limitations in range, efficiency, and usability due to bulkiness, stiffness, and impedance mismatch when used on or near the human body, especially at higher frequencies, which restricts their effectiveness in tracking and communication applications.
Innovation Solution
A flexible wireless data transceiver device with a capacitive coupling mechanism between a loop antenna and communication circuitry, using a matching network with pi-networks to match impedance and operate across various frequency bands, including 300-347 MHz, 433 MHz, and 902-928 MHz, and 2.4 GHz, allowing for efficient communication and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If RFID systems operate at higher frequencies to improve range and efficiency, then communication range and efficiency are improved, but impedance mismatch and detuning occur when in contact with the human body
Solution Approach 1:
A capacitive coupling structure is introduced as an intermediary between the antenna and communication circuitry. This capacitor couples the antenna to the communication circuitry while isolating the antenna from direct electrical connection to the body, thereby maintaining impedance matching and preventing detuning when the device is worn on or near the human body.
2Strength
If traditional RFID devices use bulky materials and construction to support antennas and electronics, then mechanical support and protection are improved, but device thickness and stiffness increase
Solution Approach 1:
The patent employs a flexible printed circuit board (FPCB) as the substrate for mounting the antenna and communication circuitry. The FPCB provides adequate mechanical support and electrical connections while being thin and flexible, eliminating the need for bulky protective enclosures and enabling the device to be comfortably worn on the body.
3Volume of moving object
If antennas are made small to reduce device size, then device compactness is improved, but radiation efficiency deteriorates
Solution Approach 1:
The patent uses a capacitive coupling structure with specifically designed capacitance values to compensate for the electrically small antenna size. The capacitor transforms the impedance characteristics, allowing a compact antenna to radiate efficiently at the operating frequency by adjusting the coupling capacitance to optimize power transfer and radiation efficiency.
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 device provides improved range, efficiency, and accuracy for wearable applications by generating its own RF energy, reducing size and bulk, and maintaining performance even when in contact with the human body, while being economical and flexible.
Implementation Method 1
a flexible antenna, coupled to associated electronics. The antenna may be capacitively coupled to the communication circuitry
Implementation Method 2
A flexible printed circuit board (PCB) may be employed to mount the antenna and communication circuitry. The PCB may be used to implement a matching network with pi-networks to match impedance
Data Source
Figure 1A~1E
Figure 2A~2D
Figure 3
AI summary
A flexible antenna capactively coupled to related circuitry components for an active wearable data transceiver electronic location and identification device. Wearable data transceivers (WDXs) are employed as bracelets, badges, and may be incorporated with back pack straps and clothing at locations such as collars, cuffs, and hems. They employ various colors. Active transceiver communication devices are also mounted on objects for real time location tracking and identification. Body-mounted WDXs match the body with the antenna for sending and receiving signals. WDX power includes coplanar battery cells and circuitry has radio transmitter and radio receiver components.