Dual-Antenna Substrate Recess for Permittivity Symmetry
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Solution Overview
Problem
Antenna devices with a first substrate having a ground and a second substrate without a ground, where antenna elements are coupled to mounting terminals instead of the ground, leading to deteriorated antenna characteristics due to asymmetry in permittivity and reduced isolation between elements.
Innovation Solution
Incorporating a recessed portion on the second substrate between antenna elements to direct electric lines through a lower permittivity layer, improving permittivity symmetry and enhancing isolation between elements and terminal portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a second substrate without a ground is used and antenna elements are coupled to mounting terminals, then the device structure is simplified, but antenna characteristics deteriorate due to asymmetry in permittivity
Solution Approach 1:
The patent intentionally introduces asymmetry by forming a recessed portion in the second substrate between the antenna elements. This recessed portion creates an air layer with lower permittivity on one side, deliberately balancing the permittivity distribution to achieve symmetry in electrical characteristics while maintaining structural simplicity. The recessed portion depth is controlled to be 0.01λ to 0.5λ to optimize the permittivity balance.
Solution Approach 2:
The patent changes the physical parameter of the second substrate by forming a recessed portion with specific depth (0.01λ to 0.5λ). This parameter change modifies the effective permittivity distribution around the antenna elements, transforming the electrical environment to achieve symmetry without adding complex ground structures.
2Area of stationary object
If antenna elements are arranged side by side on a substrate, then space is efficiently utilized, but isolation between elements deteriorates due to coupling through the substrate
Solution Approach 1:
The recessed portion filled with air (lower permittivity material) acts as an intermediary layer between the antenna elements. This air layer reduces the coupling strength between adjacent antenna elements by providing a lower permittivity path, thereby improving isolation while maintaining the compact side-by-side arrangement.
3Reliability
If a recessed portion is formed in the second substrate, then permittivity symmetry improves, but manufacturing complexity increases
Solution Approach 1:
The recessed portion divides the second substrate into distinct regions: a first region with higher permittivity (substrate material) and a second region with lower permittivity (air layer). This segmentation creates a controlled permittivity distribution that improves symmetry without requiring complex multi-layer structures or additional materials.
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
Enhances antenna characteristics by improving permittivity symmetry and isolation, reducing coupling strength, and increasing heat dissipation while maintaining structural integrity.
Implementation Method 1
a line of electric force formed between an end portion of each antenna element on an inner side in an arrangement direction and the ground passes inside the second substrate
Implementation Method 2
the symmetry of the permittivity of each antenna element in the arrangement direction (balance of the ratio of the layer outside the second substrate) largely collapses
Implementation Method 3
isolation between each antenna element and a terminal portion disposed at a position facing the antenna element with the recessed portion interposed therebetween can also be improved
Data Source
AI summary
An antenna device includes: a main substrate provided with a ground electrode extending in a Y-axis direction; and a sub-substrate mounted on the main substrate. The sub-substrate includes: an upper surface on which a first antenna element and a second antenna element are arranged side by side in the Y-axis direction; and a lower surface on which a mounting terminal portion is disposed. A recessed portion recessed toward the upper surface is formed in a central region (a region between the first antenna element and the second antenna element of the lower surface of the sub-substrate.