Window-Mounted Vehicle Antenna for Zenith Circular Polarization
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Solution Overview
Problem
Existing vehicle antenna systems face challenges in efficiently receiving circularly polarized signals from the zenith direction, particularly when antenna elements are housed inside antenna cases on the roof, leading to potential interference and reduced reception performance, especially in vehicles without protruding antenna cases.
Innovation Solution
A vehicle antenna system that integrates an antenna element with a radiating conductor on a dielectric substrate, positioned away from the window glass interior, utilizing a dielectric layer to adjust the signal receiving plane and satisfy specific permittivity and thickness equations, allowing efficient reception of circularly polarized signals without the need for an external antenna case on the roof.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If antenna elements are housed inside an antenna case on the roof of a vehicle, then directivity in the zenith direction is improved, but the structure inside the antenna case becomes complicated and interference with other antennas occurs
Solution Approach 1:
The antenna element is extracted from the traditional roof-mounted antenna case and repositioned to be attached to the window glass. This removes the need for a complex protruding antenna case structure while maintaining the antenna's functional performance for receiving satellite signals from the zenith direction.
2Reliability
If antenna elements are placed inside an antenna case on the roof of a car, then reception performance may be improved, but interference with antennas transmitting and receiving radio signals in different frequency bands occurs
Solution Approach 1:
The antenna element is relocated from the vertical roof space to the planar surface of the window glass. This dimensional change in positioning separates the antenna from other roof-mounted antennas operating in different frequency bands, eliminating interference while preserving reception performance.
3Shape
If antenna elements are mounted inside the automobile or embedded in a plastic case without protrusion, then the exterior appearance is improved, but efficient reception of circularly polarized signals from the zenith direction is compromised
Solution Approach 1:
The antenna element is attached to the window glass at a specific angle (normal direction of the first principal plane is less than or equal to 45° relative to the vertical direction) and positioned at a controlled distance from the glass surface using a dielectric layer. These parameter optimizations enable efficient reception of circularly polarized signals from the zenith direction while maintaining a flush exterior appearance without protruding antenna cases.
4Adaptability or versatility
If multiple antenna elements are mounted on an automobile in different locations, then coverage is improved, but the overall system complexity and potential for interference increases
Solution Approach 1:
The window glass-mounted antenna element design can be universally applied to multiple locations on a vehicle (e.g., front window, rear window, side windows) to provide comprehensive signal coverage. Each antenna element operates independently on its respective window surface, avoiding the interference and complexity issues associated with traditional multi-antenna roof installations.
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
The system effectively transmits and receives circularly polarized signals from the zenith direction with improved reception performance, even when the antenna element is located inside the vehicle, maintaining high front-to-back ratios and avoiding interference issues.
Implementation Method 1
the relative permittivity of the dielectric layer is εr, the thickness of the dielectric layer is t [mm], and the first frequency is f1 [MHz]
Data Source
AI summary
Provided is a vehicle antenna system that is able to efficiently receive circularly polarized signals from the zenith direction. A vehicle antenna system (100) is provided with window glass (30) for a vehicle (20) and an antenna element (40) that is able to receive signals of a predetermined frequency band. The antenna element (40) is provided on a first principal plane of a dielectric substrate (43), and includes a radiating conductor (41) that is able to receive circularly polarized signals of a first frequency, and a grounding conductor (44) positioned opposite the radiating conductor (41) via the dielectric substrate (43). The normal direction of the first principal plane is less than or equal to 45° relative to the vertical direction, and the radiating conductor (41) is positioned away from the inner surface of the window glass (30) via the dielectric layer (60) in the direction of the vehicle interior.