Adjustable Antenna Matching Network Using Non-Directional Feedback
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Solution Overview
Problem
Impedance mismatch between antennas and power amplifiers in wireless communications devices leads to reduced radiated power and efficiency, requiring over-design of power amplifiers and the use of directional couplers with limited dynamic range and increased complexity for wide frequency bands.
Innovation Solution
A mobile wireless communications device employs a non-directional coupler and an adjustable impedance matching network controlled by a feedback receiver and controller, using a least means square algorithm to adjust impedance over a wide frequency band without the need for directional couplers, thereby improving power efficiency and reducing device complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a directional coupler is used to measure forward and reflected power for impedance matching, then impedance matching can be achieved, but the device complexity increases and dynamic range is limited over wide frequency bands
Solution Approach 1:
The patent extracts the power measurement function from the directional coupler by using a simple tap coupled to the transmission line. This tap provides a signal proportional to the power level without requiring the complex directional coupling structure, thereby reducing device complexity while maintaining impedance matching capability
Solution Approach 2:
The transmission line tap serves multiple functions: it provides power level measurement and works across wide frequency bands without requiring multiple different couplers. This universal approach eliminates the need for frequency-specific directional couplers, reducing overall system complexity
2Adaptability or versatility
If multiple directional couplers are used to support wide frequency band operation, then frequency band coverage is improved, but cost and complexity increase
Solution Approach 1:
The transmission line tap design is frequency-agnostic and can operate across wide frequency bands without modification. A single tap structure provides universal power measurement functionality for all frequency bands, eliminating the need for multiple frequency-specific directional couplers
3Power
If the power amplifier is over-designed to provide sufficient output power under poor impedance matching conditions, then radiated power specification is met, but power amplifier efficiency is lowered
Solution Approach 1:
The patent implements feedback by measuring the actual power delivered to the antenna using the transmission line tap and adjusting the power amplifier output accordingly. This closed-loop control allows the PA to operate at optimal efficiency while dynamically adapting to impedance variations, eliminating the need for over-design
Solution Approach 2:
The system dynamically adjusts the power amplifier output based on real-time impedance conditions measured by the tap. Rather than being statically over-designed, the PA operates dynamically at the minimum necessary power level while maintaining specification compliance, thereby improving efficiency
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 enables efficient impedance matching across a wide frequency band, reducing the need for multiple directional couplers and lowering the cost and complexity of wireless communications devices while maintaining high power efficiency.
Implementation Method 1
a non-directional coupler coupled between the adjustable impedance matching network and the antenna and configured to sample a transmitted signal
Implementation Method 2
a feedback receiver coupled to the non-directional coupler to generate a feedback signal
Data Source
Figure 1
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Figure 4
AI summary
A mobile wireless communications device includes a portable housing, a transmitter carried by the portable housing and configured to modulate an input signal, and an adjustable impedance matching network coupled downstream from the transmitter. An antenna is coupled downstream from the adjustable impedance matching network, and a non-directional coupler is coupled between the adjustable impedance matching network and the antenna. A feedback receiver is coupled to the non-directional coupler to generate a feedback signal. A controller is configured to control the adjustable impedance matching network based upon the input signal and the feedback signal.