Vehicle Antenna Base Resin Metal Composite Grounding
Solution Overview
Problem
The existing vehicle antenna devices experience a reduction in antenna gain due to unwanted resonance between the metal-made base and the vehicle body, particularly when a resin-made base is used, which can lead to resonance issues in the required frequency band.
Innovation Solution
A vehicle antenna device design featuring a resin-made base with a smaller metal-made base that includes a cylindrical portion for attachment to the vehicle body, a conductor plate attached to the resin-made base to prevent direct contact with the vehicle body, and a filter board between the capacitive and coil elements to manage resonance frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a resin-made base is used to reduce weight and cost, then weight and manufacturing cost are reduced, but unwanted resonance occurs between the metal-made base and vehicle body causing antenna gain reduction
Solution Approach 1:
A resin-made base is introduced as an intermediary material between the metal-made base and the vehicle body. This resin base prevents direct contact between the metal base and conductive vehicle body surfaces, thereby eliminating the unwanted resonance that would otherwise occur between these two conductive elements. The resin base acts as an electrical insulator while still providing mechanical support and grounding functionality through its integrated grounding pattern.
2Area of stationary object
If the metal-made base is miniaturized to reduce size, then device complexity is reduced, but grounding effectiveness and resonance control become more difficult
Solution Approach 1:
The grounding function is segmented and distributed across two separate components: the metal-made base provides localized grounding points, while the resin-made base provides an extended grounding pattern that covers a larger area. This segmentation allows the metal base to be miniaturized while the resin base compensates for the reduced grounding area through its own extensive grounding pattern, maintaining overall grounding effectiveness.
Solution Approach 2:
The antenna base assembly uses a composite structure combining metal and resin materials, each contributing different functional properties. The metal-made base provides excellent electrical conductivity and localized grounding, while the resin-made base provides electrical insulation, mechanical support, and extended grounding capability. This composite approach allows miniaturization of the metal component while maintaining overall system performance.
3Reliability
If the antenna base is made larger to ensure gain, then antenna gain is improved, but weight and manufacturing cost increase
Solution Approach 1:
The antenna base uses a composite structure where the lightweight resin-made base provides the primary structural support and grounding function, while a smaller metal-made base provides localized high-conductivity grounding points. This composite approach maintains antenna gain requirements through effective grounding without requiring a large overall base size, thereby reducing weight compared to a fully metal construction.
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 design effectively avoids the reduction in antenna gain by shifting unwanted resonance to a lower frequency band, ensuring stable performance in the required frequency range and improving assemblability.
Implementation Method 1
a phenomenon sometimes occurs in which the metal-made base has a resonance point according to a distance with respect to the vehicle body (ground), the unwanted resonance is occurred in a required frequency band
Implementation Method 2
The conductor plate may have at least one plate spring portion which extends so as to approach the vehicle body
Data Source
AI summary
A vehicle antenna device includes: an antenna base; an antenna case which is overlaid on the antenna base; and an antenna element and an amplifier board which are disposed inside the antenna case. The antenna base has: a resin-made base which has an opening; and a metal-made base which is smaller in area than the resin-made base, the metal-made base being disposed on the resin-made base so as to close the opening, and having a cylindrical portion for attachment to a vehicle body. A conductor plate is attached to a surface of the resin-made base, the surface being opposite to a placement surface of the metal-made base.