Capacitive Resonance in Vehicle Rear Window Antennas
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Solution Overview
Problem
Existing antenna systems integrated into motor vehicle rear windows, which also function as heating fields, face challenges in maintaining optimal reception quality due to frequency dependency and resonance issues with high-frequency signals.
Innovation Solution
The solution involves a busbar structure with capacitances connected between busbars and central sections of heating wires, as well as between heating wires, to create a series resonant circuit, reducing frequency dependency and improving antenna properties by using capacitors such as electrolytic or ceramic capacitors, with values between 50 pF and 10 μF, and potentially incorporating inductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If heating wires are used as antenna elements in a rear window, then the antenna system can be integrated into the window structure, but the reception quality is affected by frequency dependency and resonance issues
Solution Approach 1:
The patent applies parameter changes by introducing capacitances with specific values (50 pF to 10 μF) to modify the electrical characteristics of the antenna system. These capacitances are connected between busbars and central sections of heating wires, or between heating wires, to create series resonant circuits that reduce frequency dependency and improve reception quality across a broad frequency range from 125 kHz to 1.6 GHz.
2Reliability
If capacitances are added to the antenna field to improve reception quality, then frequency dependency is reduced, but the device complexity increases
Solution Approach 1:
The patent merges the heating field and antenna field into a single integrated system. The heating wires serve dual purposes: they function as antenna elements for radio reception while simultaneously providing heating capability. This combination reduces the need for separate antenna structures and minimizes the additional complexity introduced by capacitances, as they are integrated into the existing heating wire configuration.
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 antenna properties by achieving a larger bandwidth and reducing resonance issues for high-frequency signals, making the antenna system less dependent on frequency, suitable for various heating field geometries and frequencies from 125 kHz to 1.6 GHz.
Implementation Method 1
a busbar and a more central section of a heating wire... is connected by a capacitance. In addition, such a capacitance can also be connected between two heating wires
Implementation Method 2
to create a series resonant circuit, reducing frequency dependency and improving antenna properties
Data Source
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AI summary
The invention relates to an improved antenna field, characterized by the following features: at least one capacitance (19') is switched between one of the two bus bars (11a, 11b) and at least one center section (9c) of the heating wire (9a, 9b, 9c) formed between 20% and 80% of the total length of the heating wire (9; 9a, 9b, 9c), and/or at least one capacitance (19”) is switched between at least two center sections (9c, 9'c) of the heating wires (9; 9a, 9b, 9c, 9'a, 9'b, 9'c) formed between 20% and 80% of the total length of two heating wires (9; 9a, 9b, 9c; 9'a, 9'b, 9'c), and the at least one capacitance (19', 19") is greater than 50 pF.