Meandering Sensing Pad Resonant Frequency Avoidance
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Solution Overview
Problem
The integration of a sensing pad with an antenna structure in mobile devices often results in interference due to their resonant frequencies being close to the antenna's operation frequency, violating SAR requirements and affecting RF power control.
Innovation Solution
An electronic device design featuring a proximity sensor, an antenna structure with separate adjacent radiation elements, and a sensing pad with specific branch configurations that avoid resonant frequency overlap with the antenna's frequency bands, ensuring non-interference and optimal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sensing pad is integrated with the antenna structure, then device size is reduced and manufacturing cost is lowered, but the resonant frequency of the sensing pad interferes with the antenna operation frequency, causing SAR requirement violations and RF power control issues
Solution Approach 1:
The patent changes the physical parameters of the sensing pad by introducing meandering branches that increase the electrical path length without increasing the physical footprint. This modifies the resonant frequency of the sensing pad to be distinct from the antenna operation frequencies, thereby eliminating frequency interference while maintaining compact integration
Solution Approach 2:
The sensing pad transitions from a simple linear or planar structure to a meandering three-dimensional path configuration. By utilizing vertical and lateral dimensions through the meandering design, the pad achieves longer electrical length for frequency tuning within the same planar area, resolving the frequency conflict while maintaining compact size
2Device complexity
If the sensing pad uses a simple linear structure, then manufacturing is easier and device complexity is reduced, but the resonant frequency cannot be sufficiently separated from the antenna operation frequency, leading to interference
Solution Approach 1:
The meandering branch design changes the electrical parameters (inductance and capacitance) of the sensing pad by increasing the current path length. This parameter modification shifts the resonant frequency away from the antenna operation frequencies, achieving frequency separation without requiring complex multi-component circuits
Solution Approach 2:
The sensing pad employs curved meandering paths instead of straight linear segments. These curved geometries increase the electrical length and modify the distributed inductance and capacitance, thereby tuning the resonant frequency to avoid interference with the antenna while maintaining a simple single-structure design
3Device complexity
If the sensing pad resonant frequency is close to the antenna operation frequency, then the device structure is simpler, but RF power control is affected and SAR requirements are violated
Solution Approach 1:
By changing the geometric parameters of the sensing pad through meandering branches, the patent achieves frequency separation that prevents the sensing pad from interfering with RF power control operations. The modified resonant frequency ensures that proximity detection operations do not disrupt the antenna's RF transmission and reception
Solution Approach 2:
The sensing pad is segmented into multiple meandering sections that collectively create the desired electrical length and resonant characteristics. This segmentation allows for fine-tuning of the resonant frequency through geometric adjustments without requiring additional separate frequency control components
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 enhances radiation efficiency, increases detectable distance, minimizes device size, and reduces manufacturing costs while meeting SAR requirements for mobile communication devices.
Implementation Method 1
The antenna structure includes a first radiation element and a second radiation element which are separate from and adjacent to each other. The first radiation element has a feeding point. The second radiation element is coupled to a ground voltage. The antenna structure covers a first frequency band and a second frequency band.
Implementation Method 2
The resonant frequency of the sensing pad is neither within the first frequency band nor within the second frequency band. The second branch has a meandering shape.
Data Source
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AI summary
An electronic device includes a proximity sensor, an antenna structure, and a sensing pad. The antenna structure includes a first radiation element and a second radiation element which are separate from and adjacent to each other. The first radiation element has a feeding point. The second radiation element is coupled to a ground voltage. The sensing pad is adjacent to the antenna structure. The sensing pad includes a main branch, a first branch, and a second branch. The main branch is coupled to the proximity sensor. The first branch and the second branch are coupled to the main branch. The second branch has a meandering shape. The antenna structure covers a first frequency band and a second frequency band. The resonant frequency of the sensing pad is neither within the first frequency band nor within the second frequency band.