Folded Automotive Window Antenna for Balanced Circular Polarization
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Solution Overview
Problem
Existing antennas for receiving satellite waves on automotive windows face challenges in providing excellent reception performance on narrow areas without interfering with the driver's field of view and in achieving balanced directivity for circularly polarized waves.
Innovation Solution
A glass antenna design featuring a core-side and earth-side power feeding unit with orthogonal elements of specific lengths, a parasitic element, and a bridge line to improve directivity and sensitivity, configured to be arranged along a vehicle body flange to minimize visual interference and enhance GPS signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large distinct antenna pattern is disposed on the glass plate, then reception performance is improved, but it interferes with the driver's field of view
Solution Approach 1:
The patent transitions from traditional planar antenna patterns to a three-dimensional folded structure. The antenna elements are bent and folded multiple times (first fold, second fold, third fold) to create a compact volumetric configuration that achieves the required electrical length and radiation characteristics without occupying large surface area on the glass plate, thus not obstructing the driver's view.
2Reliability
If the antenna elements are made longer to improve reception, then the antenna occupies more space on the glass plate, but the available area is limited
Solution Approach 1:
The antenna elements are folded multiple times in three-dimensional space (first fold, second fold, third fold) to achieve the required electrical length within a compact footprint. This allows the antenna to maintain sufficient element length for good reception performance while occupying minimal surface area on the glass plate.
Solution Approach 2:
The antenna structure employs nested folding where elements are folded within the space created by previous folds, creating a compact nested configuration. The first, second, and third folds are arranged to nest within each other, maximizing space utilization and achieving long electrical length in a small physical footprint.
3Ease of manufacture
If traditional antenna patterns are used, then manufacturing is simpler, but achieving balanced directivity for circularly polarized waves is difficult
Solution Approach 1:
The patent introduces asymmetry in the antenna structure through unequal folding configurations. The first, second, and third folds have different geometries and orientations, creating an asymmetric three-dimensional structure that achieves balanced directivity for circularly polarized waves. This asymmetric folding pattern allows the antenna to radiate equally in horizontal and vertical planes while maintaining manufacturability through standard fabrication processes.
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 antenna achieves equalized directivity in the front-rear and left-right directions, improving receiving sensitivity for circularly polarized waves, particularly in the 1 to 2 GHz band, while maintaining a compact form that does not obstruct the driver's view.
Implementation Method 1
a first element (1) extending from the core-side power feeding unit (4)... and a second element (2) extending at an angle of approximately 90 degrees with respect to the first element (1) from the core-side power feeding unit (4)
Data Source
Figure 1~2
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AI summary
To provide excellent reception performance on a narrow area of an automotive window glass, it is provided an antenna to be arranged on a window glass of a vehicle, the antenna comprising: a core-side power feeding unit; an earth-side power feeding unit; a first element extending from the core-side power feeding unit; and a second element extending at an angle of approximately 90 degrees with respect to the first element from the core-side power feeding unit, the first element having a length of 3αλ/4+δ and the second element having a length of αλ/4-δ, or the first element having a length of 3αλ/4-δ and the second element having a length of αλ/4+δ, where λ refers to a wavelength of a reception frequency, α refers to a wavelength shortening rate of glass, and δ refers to an offset length for each of the first element and the second elements.