Partial Metal Back Mobile Device Antenna Isolation
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Solution Overview
Problem
MIMO multi-band antennas in partial metal housing handsets face performance deterioration due to interference from the metal back, making it challenging to achieve good diversity and capacity performance across multiple operating frequencies.
Innovation Solution
The design features multi-band antennas located inside the device on a non-conducting chassis with a conducting central portion, allowing radiating arms to clear the conducting central portion and connect to antenna feeds and a ground plane, minimizing interference and enabling resonance across 710-960 MHz, 1710-2100 MHz, and 2300-2700 MHz frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multi-band antennas are placed in a partial metal back handset, then the number of antennas is reduced and multi-frequency operation is achieved, but antenna performance deteriorates due to metal interference
Solution Approach 1:
A non-conducting chassis is introduced as an intermediary between the metal back and the antennas. The chassis includes a non-conducting portion that positions the antennas away from the metal back, and a conducting central portion that provides grounding while maintaining separation. This mediator structure enables the antennas to operate in a partial metal back handset without direct contact with the interfering metal surface.
2Volume of moving object
If antennas are positioned close to the metal back to save space, then device compactness is improved, but interference from the metal back increases and antenna performance deteriorates
Solution Approach 1:
The antenna positioning problem is solved by transitioning from a two-dimensional planar arrangement to a three-dimensional configuration. The non-conducting chassis creates a vertical separation between the antennas and the metal back, allowing the antennas to be positioned in the Z-dimension away from the interference source while maintaining horizontal integration within the device footprint.
3Strength
If a fully metal back is used for aesthetic and structural purposes, then device appearance and strength are improved, but antenna performance deteriorates due to interference
Solution Approach 1:
The back housing is designed with heterogeneous material properties: a conducting central portion for grounding and structural support, and non-conducting portions for aesthetic appearance and antenna isolation. This local differentiation allows different regions of the back housing to serve different functions - the conducting portion provides strength and grounding while the non-conducting portions prevent interference with antenna operation.
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
This configuration maintains antenna performance by minimizing interference from the metal back, ensuring effective operation across multiple frequency bands with reduced overlap and enhanced radiation efficiency, meeting target specifications for each frequency range.
Implementation Method 1
the partial metal back can interfere with the antenna; hence, when the multi-band antennas are put in the partial metal back handset, their performance deteriorates
Implementation Method 2
Each multi-band antenna can resonate in three different frequency ranges including, but not limited to, 710-960 MHz, 1710-2100 MHz and 2300-2700 MHz
Data Source
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AI summary
A mobile device having an interior multiband antenna and a partially metal back is provided. The device comprises: a back side (201) comprising: a conducting central portion; non-conducting portions comprising respective widths from respective end edges of the back side (201) to the conducting central portion, the conducting central portion separating the non-conducting portions; an interior chassis covered by the back side (201); antennas located on the interior chassis behind each of the non-conducting portions, each of the antennas comprising at least two respective radiating arms configured to resonate in at least three frequency ranges; one or more antenna feeds connected to each of the antennas; and, a switch (115) configured to select one or more of the antennas for operation.