Antenna Grounding Rings for Wireless Charging Efficiency
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Solution Overview
Problem
In electronic devices with compact wireless circuitry, there is a challenge in maximizing antenna efficiency and bandwidth while minimizing interference and maintaining wireless charging efficiency, as radio-frequency signals can induce currents on coil structures, leading to signal losses.
Innovation Solution
The implementation of antenna grounding ring structures formed from concentric ring-shaped traces on a flexible printed circuit, which couple antenna currents to the ground traces, preventing signal losses and allowing the ground traces to form part of the antenna, thereby maximizing antenna volume and efficiency bandwidth without impairing wireless charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the antenna resonating element is made larger to increase efficiency bandwidth, then antenna efficiency bandwidth is improved, but device size increases and interference with other components worsens
Solution Approach 1:
The patent combines the antenna ground trace with the sensor board ground trace by using the sensor board's ground trace as part of the antenna structure. This merging allows the antenna to effectively utilize the existing ground plane area without requiring additional space, thereby increasing antenna efficiency bandwidth while maintaining compact device dimensions.
Solution Approach 2:
The sensor board ground trace serves dual functions: it provides the ground reference for sensor operations and simultaneously acts as part of the antenna structure for RF signal transmission. This multi-functionality allows the same physical structure to support both sensor functionality and enhanced antenna performance without increasing overall device volume.
2Reliability
If the antenna resonating element is made larger to increase efficiency bandwidth, then antenna efficiency bandwidth is improved, but interference with other components worsens
Solution Approach 1:
The patent combines the antenna ground trace with the sensor board ground trace by using the sensor board's ground trace as part of the antenna structure. This merging allows the antenna to effectively utilize the existing ground plane area without requiring additional space, thereby increasing antenna efficiency bandwidth while maintaining compact device dimensions.
Solution Approach 2:
The antenna grounding ring structure acts as an intermediary element that couples the antenna resonating element to the sensor board ground trace. This grounding ring provides a controlled impedance path and isolates the antenna currents from interfering with adjacent components while maintaining the desired RF performance.
3Reliability
If ground traces are used to form part of the antenna to maximize antenna volume, then antenna efficiency bandwidth is improved, but wireless charging efficiency deteriorates due to induced currents on coil structures
Solution Approach 1:
The grounding structure is segmented into frequency-selective sections that differentially handle RF and wireless charging frequencies. The grounding ring structure includes capacitive coupling elements that are tuned to pass RF signals while blocking wireless charging frequencies, thereby separating the two functional requirements within the same ground trace system.
Solution Approach 2:
Different portions of the grounding system are designed with different electrical characteristics. The grounding ring near the antenna resonating element provides RF grounding with capacitive coupling, while the connection to the sensor board ground trace provides a low-impedance path for wireless charging frequencies. This local differentiation allows each region to optimize for its specific frequency range.
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
This configuration enhances antenna efficiency by shorting antenna currents at the first frequency and blocking currents at the second frequency, optimizing antenna performance across various frequency bands while maintaining wireless charging efficiency.
Implementation Method 1
Antenna currents at the first frequency may be coupled onto the ring-shaped traces by near-field capacitive coupling
Implementation Method 2
The coil structures may receive wireless charging signals at a second frequency that is less than the first frequency through the rear housing wall
Data Source
AI summary
An electronic device may include a rear housing wall, antenna resonating element, coil, sensor board, and antenna grounding ring structures. The coil may receive wireless charging signals through the grounding ring structures and the rear housing wall. The grounding ring structures may include concentric ring-shaped traces. The ring-shaped traces may be separated by at least one gap. The ring-shaped traces and the gaps may configure the grounding ring structures to short antenna currents at relatively high frequencies from the antenna resonating element to a ground trace on the sensor board while blocking currents at relatively low frequencies. This may allow the ground trace to form part of an antenna without substantially impairing wireless charging efficiency of the coil.