Switchable Matching Antenna Assembly for Metal Surface Mounting
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Solution Overview
Problem
Antennas in electrical devices face efficiency and radiation pattern issues when mounted on different surfaces, including metal, which affects their operation and limited space constraints within the devices.
Innovation Solution
An antenna assembly with a switchable matching circuit coupled to the antenna element, allowing impedance adjustment and improved performance on various surfaces, including metal, through a grounding circuit and substrate configuration that enhances radiation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the antenna is mounted on a metal surface, then the electrical device can be securely mounted, but the antenna efficiency and radiation pattern are affected negatively
Solution Approach 1:
A non-conductive spacer is introduced between the antenna and the metal mounting surface. This intermediary element electrically isolates the antenna from the conductive metal surface, preventing the metal from interfering with the antenna's electromagnetic field and radiation pattern, while still allowing the device to be securely mounted to the metal surface.
2Reliability
If the antenna is mounted on non-metal surfaces, then the antenna operates efficiently, but the mounting strength and security are reduced
Solution Approach 1:
The mounting system is divided into separate functional components: a mounting bracket that attaches to the surface (providing mechanical strength), and the antenna assembly that is positioned and isolated from the surface (providing electromagnetic performance). This segmentation allows each component to optimize its specific function without compromising the other.
3Volume of moving object
If the electrical device is made small with low profile, then the device size is reduced, but the space available for the antenna is limited
Solution Approach 1:
The antenna is designed to utilize the vertical dimension and three-dimensional space within the compact device housing, rather than requiring large planar area. The antenna structure is configured to radiate effectively within the constrained volume, employing spatial arrangement and dimensional optimization to achieve adequate radiation performance in a small form factor.
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 solution ensures efficient wireless communication across different mounting orientations and surfaces, including metal, by adjusting impedance and reducing return loss, thereby maintaining effective radiation efficiency.
Implementation Method 1
The switchable matching circuit changes a feed impedance of the feed circuit
Implementation Method 2
Antennas are used in electrical devices to wirelessly communicate with other devices
Implementation Method 3
The antenna element is coupled to the feed circuit and the ground circuit
Data Source
Figure 1~2
Figure 3~5
Figure 6
AI summary
An electrical device includes a device housing having an internal cavity. The electrical device includes a device sensor in the internal cavity. The electrical device includes a control circuit board in the internal cavity. The control circuit board includes a sensor circuit coupled to the device sensor. The control circuit board includes a ground circuit and a communication circuit with a feed circuit. The electrical device includes an antenna assembly coupled to the control circuit board. The antenna assembly includes a substrate mounted to the control circuit board and an antenna element extending along at least one surface of the substrate. The antenna element is coupled to the feed circuit and the ground circuit. The antenna assembly includes a switchable matching circuit coupled to the antenna element. The switchable matching circuit changes a feed impedance of the feed circuit.