Rear Glass Shared Antenna AM FM Sensitivity Optimization
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Solution Overview
Problem
The reception sensitivity of AM/FM shared antennas deteriorates when the AM antenna is positioned near metallic regions on the rear glass of a vehicle, leading to insufficient FM reception performance.
Innovation Solution
A rear glass design with a shared antenna system where the AM antenna's element length is optimized to satisfy the relationship 0.49×α×λFM-C≤LAM≤0.67×α×λFM-C, and the FM antenna is capacitively coupled to the defogger, ensuring improved reception sensitivity for both AM and FM signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the shared antenna is positioned closer to metallic regions to increase space utilization, then device complexity is reduced, but reception sensitivity deteriorates
Solution Approach 1:
The patent changes the parameter of AM antenna element length to satisfy the specific relationship with FM wavelength and glass plate wavelength shortening coefficient. This allows the antenna to be positioned closer to metallic regions (improving space utilization and reducing device complexity) while maintaining good reception sensitivity for both AM and FM bands
2Reliability
If the AM antenna element length is increased to improve AM reception, then AM reception sensitivity is improved, but interference with FM antenna increases
Solution Approach 1:
The patent optimizes the AM antenna element length parameter to satisfy 0.49×α×λFM-C≤LAM≤0.67×α×λFM-C. This optimized parameter range allows the AM antenna to achieve good AM reception sensitivity while minimizing interference with the FM antenna, as the length is carefully controlled to avoid resonant frequencies that would cause harmful interference
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 the reception sensitivity for both AM and FM signals, reducing interference and improving the flexibility of antenna design, while maintaining effective AM reception performance.
Implementation Method 1
the second FM antenna element can be capacitively coupled to the heating wire most closely approaching the FM antenna, among the heating wires of the defogger
Data Source
AI summary
A rear glass according to the invention is for attachment to a lift-up backdoor that closes an opening in a rear portion of a vehicle, and includes a glass plate, a defogger disposed in a vicinity of a center of the glass plate in an up-down direction, and a shared antenna installed on the glass plate upward or downward of the defogger, the shared antenna including a power supply unit, an AM antenna connected to the power supply unit, and an FM antenna connected to the power supply unit, and a relationship between an element length LAM of the AM antenna, a center wavelength λFM-C corresponding to a reception frequency band of the FM antenna and a wavelength shortening coefficient α of the glass plate satisfying 0.49×α×λFM-C≤LAM≤0.67×α×λFM-C.