Double-Case Antenna Layout for Water-Tight AM/FM Reception
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Solution Overview
Problem
The existing small-height type antenna devices with a double-case structure face challenges in maintaining electrical performance and increasing manufacturing costs due to reduced housing space and complex structures, which degrade antenna performance when trying to position the antenna element high enough for AM/FM band reception.
Innovation Solution
The antenna device positions the antenna element between the outer and inner cases, maintaining water-tightness and electrical connectivity, allowing for a simpler structure and reduced costs while ensuring performance comparable to single-case structures within the same size constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna element is housed inside the inner case in a double-case structure, then the housing space is reduced, but the antenna performance is degraded
Solution Approach 1:
The antenna element is positioned on the outer surface of the inner case rather than inside it, utilizing the three-dimensional space between the inner and outer cases. This dimensional repositioning allows the antenna element to maintain its required area and height for proper AM/FM band reception while still benefiting from the compact double-case structure.
2Reliability
If the double-case structure is implemented, then the water-tightness is improved, but the structure complexity increases
Solution Approach 1:
The inner case is nested within the outer case, with the antenna element positioned on the outer surface of the inner case. This nested configuration provides water-tight protection for the housing space while maintaining a compact overall structure. The simplicity of the nested design reduces structural complexity compared to more elaborate sealing mechanisms.
3Reliability
If the antenna element is positioned high for AM/FM reception, then the electrical performance is improved, but the height constraint is violated
Solution Approach 1:
Instead of increasing height vertically, the antenna element is positioned horizontally on the outer surface of the inner case, utilizing the lateral space between the inner and outer cases. This allows the antenna element to achieve the necessary effective area and electrical performance for AM/FM band reception while keeping the overall height within the 70 mm constraint.
Data Source
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AI summary
Provided is an antenna device capable of simplifying a structure while preventing degradation of antenna performance even with an upright type double-case structure. An antenna device (1) having a double-case structure includes an inner case (13) inside of which a housing space is formed so as to house a coil element (12) and the like therein, the inner case (13) being covered with an outer case (15). An antenna element (14) is provided between an outer surface of the inner case (13) and an inner surface of the outer case (15). The antenna element (14) is electrically connected to the coil element (12) provided in the housing space while keeping water-tightness of the housing space.