Back Cover AMC Structure for Millimeter-Wave Antenna Radiation
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Solution Overview
Problem
Conventional terminals experience significant energy loss and damage to the radiation pattern of antennas, particularly in the millimeter-wave frequency band, due to surface waves generated on the back cover, which affects the antenna's receiving and sending performance.
Innovation Solution
A multi-frequency AMC structure is integrated into the inner surface of the non-metallic back cover to block electromagnetic wave propagation and prevent surface waves, featuring an opening for perpendicular radiation and a high-impedance surface with positive reflection phase coefficients to enhance radiation pattern concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna is placed under the back cover, then the device structure is compact, but surface waves are generated on the back cover causing energy loss and radiation pattern damage
Solution Approach 1:
An AMC structure is introduced as an intermediary component between the antenna and the back cover. This structure acts as a mediator that prevents harmful surface wave propagation while allowing the antenna to remain under the back cover for compact device design. The AMC structure serves as a protective layer that transmits the useful radiation field while blocking the harmful surface waves.
Solution Approach 2:
The back cover structure is segmented into multiple functional layers: the original back cover, the added AMC structure with periodic unit cells, and the opening region. This segmentation allows different regions to perform different functions - the AMC structure blocks surface waves while the opening allows radiation field transmission, resolving the contradiction between compactness and energy loss.
2Volume of moving object
If the antenna is placed under the back cover, then the device structure is compact, but the radiation pattern is damaged
Solution Approach 1:
The AMC structure serves as an intermediary that preserves the radiation pattern by blocking surface wave propagation. It allows the antenna to maintain its position under the back cover for compactness while preventing the distortion of radiation patterns caused by surface waves on the back cover.
Solution Approach 2:
The back cover structure is made non-uniform by introducing the AMC structure with specific periodic unit cells in certain regions while leaving other regions (opening) transparent. This local differentiation allows the radiation pattern to be preserved in the opening region while surface waves are blocked in the AMC structure region.
3Loss of energy
If a multi-frequency AMC structure is added to the back cover, then surface wave propagation is blocked and radiation pattern is improved, but the device complexity increases
Solution Approach 1:
The AMC structure is extracted as a separate, modular component that can be independently designed and manufactured. This extraction allows the complex surface wave blocking function to be separated from the basic back cover structure, making the overall system more manageable despite the added complexity.
Solution Approach 2:
The AMC structure is designed with multi-frequency resonance capabilities, allowing a single structure to perform surface wave blocking across multiple frequency bands. This multi-functionality reduces the overall complexity compared to using separate structures for each frequency band.
4Reliability
If the multi-frequency AMC structure is fastened to the non-metallic plate body, then surface wave propagation is blocked, but the manufacturing complexity increases
Solution Approach 1:
The manufacturing process is segmented into steps: first manufacturing the basic non-metallic back cover, then separately creating the AMC structure with periodic unit cells, and finally assembling them together. This segmentation allows each component to be optimized for its specific manufacturing requirements while maintaining overall reliability.
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 reduces energy loss, improves radiation pattern, and enhances the receiving and sending performance of the antenna by preventing surface wave propagation and optimizing radiation directionality.
Implementation Method 1
a high-impedance surface formed by the multi-frequency AMC structure has a characteristic that a reflection phase coefficient is positive, so that a concentration capability of the radiation pattern of the antenna can be improved
Implementation Method 2
the opening is configured to allow an electromagnetic wave signal to pass through the back cover in a direction perpendicular to the non-metallic plate body
Data Source
AI summary
A terminal includes a back cover and an antenna. The back cover includes a non-metallic plate body and a multi-frequency AMC structure. The multi-frequency AMC structure is attached to the inner surface of the non-metallic plate body, or the multi-frequency AMC structure is embedded into the non-metallic plate body. A middle part of the multi-frequency AMC structure has an opening, and the antenna is located on an inner side of the back cover and is disposed directly facing the opening. The multi-frequency AMC structure comprises a first AMC structure and a second AMC structure, a resonance frequency of the first AMC structure is a first resonance frequency, a resonance frequency of the second AMC structure is a second resonance frequency, and the first resonance frequency is lower than the second resonance frequency.