Diversity Antenna Switching for Wireless Device Interference
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Solution Overview
Problem
Designing small-sized wireless communications devices with internal antennas that achieve adequate electromagnetic isolation between diversity and main antennas, particularly in multi-band configurations, is challenging due to destructive interference in specific frequency bands.
Innovation Solution
The implementation of a switch mechanism between the diversity and main antennas, which tunes the diversity antenna into a diversity frequency band and disconnects it in non-diversity bands to prevent cross-coupling, while also allowing for load impedance changes to enhance antenna performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If two antennas are placed in close proximity to achieve small device size, then device compactness is improved, but electromagnetic isolation between antennas deteriorates causing destructive interference
Solution Approach 1:
The patent implements a dynamic switching mechanism that changes the operational state of the diversity antenna based on the active frequency band. A switch circuit is controlled by a microcontroller to connect or disconnect the diversity antenna from the RF circuitry depending on whether diversity is needed for the currently active band, thereby adapting the antenna system to different operating conditions
Solution Approach 2:
The patent changes the electrical parameters of the diversity antenna system by adjusting its connection state (connected/disconnected) based on the active frequency band. The microcontroller monitors which band is active and modifies the circuit configuration accordingly, changing the electrical behavior of the antenna system to prevent interference while maintaining diversity when needed
2Reliability
If diversity antenna is tuned into non-diversity band to reduce interference, then diversity performance is improved, but interference remains in non-diversity band
Solution Approach 1:
The system dynamically adjusts the diversity antenna connection state based on the active frequency band. When operating in diversity bands (850/1900), the diversity antenna is connected to provide diversity performance. When operating in non-diversity bands (900/1800), the diversity antenna is disconnected to eliminate interference, thus adapting to different operational requirements
3Object-affected harmful factors
If switch mechanism is added to control antenna connection, then electromagnetic isolation is improved, but device complexity increases
Solution Approach 1:
The system uses the existing microcontroller in the mobile device to control the antenna switching, rather than adding a separate control unit. The microcontroller monitors which frequency band is active and automatically controls the switch circuit accordingly, allowing the existing processing unit to serve multiple functions including antenna management
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 interference between antennas, maintaining performance in diversity bands and improving radiated performance by making the diversity antenna electromagnetically invisible in non-diversity bands, thus addressing the challenge of size constraints and interference issues in multi-band wireless communications devices.
Implementation Method 1
the radiating elements must be electromagnetically isolated
Implementation Method 2
tunes the diversity antenna into a diversity communications frequency band to achieve a diversity mode of operation
Implementation Method 3
making the diversity antenna electromagnetically invisible in non-diversity bands
Data Source
AI summary
A mobile wireless communications device has a portable handheld housing. A circuit board is carried by the portable handheld housing. RF circuitry is carried by the circuit board. A diversity antenna and main antenna are carried by the portable handheld housing and coupled to the RF circuitry and operative together. The RF circuitry tunes the diversity antenna into a diversity communications frequency band to achieve a diversity mode of operation with the main antenna and tunes the diversity antenna into a non-diversity communications frequency band when cross-coupling has occurred from the diversity antenna to the main antenna when operating in the diversity communications frequency band. A switch is carried by the portable handheld housing and connected to the RF circuitry and coupled between the diversity and main antennae and disconnects the diversity antenna when operating in the non-diversity band to prevent cross-coupling from the diversity antenna to the main antenna.