Frequency Selective Grounding Circuit for Mobile Wireless Device
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Solution Overview
Problem
The challenge in designing mobile wireless communications devices is to create housings and antennas that provide desired operating characteristics and grounding capability within the limited space available, while minimizing the detrimental impact of metallic materials on antenna performance across multiple frequency bands.
Innovation Solution
A frequency selective grounding circuit is implemented, using series or parallel resonators to form a harmonic trap that responds to specific frequency ranges, allowing for programmable frequency response and optimal grounding locations that minimize destructive interference and maintain radiation performance across various bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metallic materials are used in housing to provide structural integrity and aesthetic appearance, then strength and shape are improved, but antenna performance deteriorates due to destructive interference and resonance across multiple frequency bands
Solution Approach 1:
The patent applies local quality by creating frequency-selective grounding circuits at specific locations around the metallic housing ring. Instead of uniformly treating the entire metallic structure, grounding circuits are strategically placed at locations where they most effectively counteract destructive resonances for specific frequency bands, allowing the housing to maintain its metallic construction while preserving antenna performance through localized electromagnetic interference management.
Solution Approach 2:
The patent employs parameter changes by using frequency-selective grounding circuits with specific inductance and capacitance values that are tuned to counteract resonances at particular frequency bands. The grounding circuits are designed with specific L and C parameters that create destructive interference for unwanted resonances while maintaining constructive interference for desired operating frequencies, thereby changing the electromagnetic parameters of the housing structure in a controlled manner.
2Reliability
If grounding circuits are added to reduce destructive resonances, then antenna performance is improved, but device complexity increases due to additional components and circuitry
Solution Approach 1:
The patent uses parameter changes by designing grounding circuits with specific inductance and capacitance values that are optimized for particular frequency bands. Each grounding circuit is tuned with precise L and C parameters to target specific resonance frequencies, allowing the system to maintain simple circuit topologies while achieving complex frequency-selective grounding behavior through careful parameter selection and tuning.
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 solution effectively reduces destructive resonances and maintains radiation performance by grounding the metallic ring at specific locations, ensuring the device operates efficiently across multiple frequency bands without degrading antenna performance.
Implementation Method 1
A frequency selective grounding circuit is implemented, using series or parallel resonators to form a harmonic trap that responds to specific frequency ranges
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4B
AI summary
A mobile wireless communications device includes a portable housing (21) having a metallic front housing (26) forming a peripheral sidewall as a metallic ring (28). A circuit board (30) is carried by the portable housing and forms a chassis ground plane. A wireless communications circuit (32) is carried by the circuit board. An antenna circuit (34) is carried by the circuit board and connected to the wireless communications circuit. A frequency selective grounding circuit (40,42,44) is positioned at a selected grounding location at the chassis ground plane and metallic front housing and forms a harmonic trap that responds to a specific range of frequencies.