Antenna Tuning Circuit for Precise SAR Suppression
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Solution Overview
Problem
Existing methods for reducing antenna specific absorption rate (SAR) impose high requirements on wiring and have low suppression precision, making it difficult to accurately reduce power at the target band without affecting other frequency points.
Innovation Solution
A circuit comprising an impedance tuning circuit with a first antenna tuning switch and resistor, and an RF filter circuit with a second antenna tuning switch, controlled by an external controller to adjust connections based on SAR test results, allowing for precise power suppression at specific or whole frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the maximum gain point of the antenna is changed to disperse the hot spot of radiation, then the SAR is reduced, but the wiring requirements become more complex and implementation becomes difficult
Solution Approach 1:
The patent changes the electrical parameters of the antenna system by introducing an impedance tuning circuit that adjusts impedance values. This allows the antenna to operate at different frequency points with different radiation patterns, effectively changing the gain distribution without physical rewiring. The impedance tuning circuit modifies the electrical characteristics to disperse the hot spot while maintaining simple wiring.
2Object-affected harmful factors
If the antenna conduction power is reduced to lower SAR, then the SAR is reduced, but the power control becomes limited by 3GPP requirements and cannot precisely suppress target band power
Solution Approach 1:
The patent segments the frequency spectrum into multiple frequency points, each with different SAR characteristics. Instead of uniformly reducing power across all bands, the system selectively adjusts impedance at specific frequency points where SAR is excessive. This segmented approach allows precise suppression of target band power while maintaining required power levels in other bands, achieving both SAR reduction and precision control within 3GPP requirements.
3Object-affected harmful factors
If existing SAR reduction methods are implemented, then some SAR reduction is achieved, but the suppression precision is low and other frequency points are affected
Solution Approach 1:
The patent applies local quality by making the impedance tuning circuit frequency-selective. Different impedance values are applied at different frequency points based on their individual SAR characteristics. This allows the system to reduce SAR at specific frequency points where it is excessive while maintaining optimal performance at other frequency points, achieving high frequency selectivity and precise localized suppression without affecting other bands.
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 effectively reduces antenna SAR by dividing voltage with the impedance tuning circuit and filtering specific or all frequency bands with the RF filter circuit, while minimizing wiring adjustments and ensuring precise suppression of target band power without affecting other frequency points.
Implementation Method 1
the first antenna tuning switch and the resistor at the impedance tuning circuit to divide the voltage, the power at the frequency point may be reduced
Implementation Method 2
filtering specific or all frequency bands with the RF filter circuit
Data Source
AI summary
A circuit includes an impedance tuning circuit, a first antenna tuning switch and a resistor. An antenna end of the first antenna tuning switch is electrically connected with an external antenna signal source. A control end of the first antenna tuning switch is electrically connected with an external controller. A first RF output end of the first antenna tuning switch is electrically connected with one end of the resistor, and the other end of the resistor and a second RF output end of the first antenna tuning switch are electrically connected with one end of the impedance tuning circuit. The other end of the impedance tuning circuit is electrically connected with the antenna. The external controller controls the antenna end to be connected with the first RF output end or the second RF output end according to an SAR test result of the antenna.