Annular Antenna Notch Structure for Stable Resonance in Small Wearables
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Solution Overview
Problem
Miniaturization of antennas in electronic devices such as electronic timepieces leads to a shift in resonant frequency, causing them to operate outside the desired frequency band.
Innovation Solution
The antenna is designed with an annular shape and includes notches and protrusions to increase the inner perimeter, along with a dielectric resin case to maintain resonance within the desired frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna element is miniaturized to improve device size, then the device can be worn more comfortably, but the resonant frequency shifts to higher frequencies causing the antenna to operate outside the desired frequency band
Solution Approach 1:
The patent applies asymmetry by introducing notches at specific positions on the annular antenna element. These notches create an asymmetric geometry that increases the effective electrical length of the antenna without increasing its physical size. The asymmetric distribution of conductive material modifies the current path length, allowing the miniaturized antenna to resonate at the desired lower frequency band rather than shifting to higher frequencies.
Solution Approach 2:
The patent utilizes the dimensional approach by adding notches that extend in the radial direction from the annular structure. This creates additional dimensional complexity in the antenna geometry, transforming a simple planar ring into a multi-dimensional structure with varying radial depths. This dimensional modification increases the effective electrical length while maintaining compact physical dimensions.
2Reliability
If the antenna is accommodated inside the electronic device case, then protection from oxidation and corrosion is improved, but the antenna size is constrained making miniaturization difficult
Solution Approach 1:
The patent implements nesting by integrating the annular antenna element within the electronic device case structure. The antenna is positioned inside the case, utilizing the internal space efficiently. The notches in the annular structure allow the antenna to be nested within the limited space while maintaining its protective enclosure, achieving both corrosion resistance through case accommodation and miniaturization through efficient space utilization.
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
An antenna (6) has an annular shape in a plan view from a first direction (I) and has at least an outer peripheral edge (60a) and an inner peripheral edge (60b). The antenna includes at least one latch (63) on the inner peripheral edge. The inner peripheral edge has at least one first notch (64) at which the inner peripheral edge is away from a center of the annular shape in the plan view.