Thermo-electric Actuator for Base Station Antenna Phase Shifting
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Solution Overview
Problem
Conventional base station antennas require large, complex, and costly mechanical systems for variable phase shifters to achieve remote electrical tilt, which increases size, cost, and complexity while compromising power handling and passive intermodulation performance.
Innovation Solution
The use of thermo-electric actuators with shape-memory alloys (SMAs) to mechanically actuate variable length signal paths in phase shifters, allowing for efficient and programmable phase shifts without the need for extensive mechanical systems, thereby reducing size, cost, and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional mechanical systems are used for variable phase shifters, then remote electrical tilt function is achieved, but device complexity and size increase
Solution Approach 1:
The patent replaces conventional mechanical actuation systems with a thermo-electric actuator that uses thermal expansion and contraction of shape-memory alloy to mechanically actuate the variable length signal path. This substitution eliminates complex mechanical linkages, motors, and control systems while achieving the same phase shifting function through a solid-state thermal-mechanical effect.
Solution Approach 2:
The invention changes the operating parameter from mechanical force/displacement to temperature. By applying electrical current to heat the shape-memory alloy, the material undergoes a phase transformation that changes its physical dimensions, which in turn actuates the signal path length. This parameter change from mechanical to thermal domain simplifies the overall system architecture.
2Adaptability or versatility
If conventional mechanical systems are used for variable phase shifters, then remote electrical tilt function is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive mechanical actuation systems with a thermo-electric actuator based on shape-memory alloy. This substitution eliminates the need for motors, gear trains, bearings, and associated control electronics, significantly reducing bill of materials cost and assembly complexity while maintaining the remote electrical tilt functionality.
Solution Approach 2:
The shape-memory alloy element serves as a simple, inexpensive actuator that can be easily manufactured and replaced if needed. Its solid-state nature and lack of moving parts make it more reliable and cheaper than conventional mechanical actuators, aligning with the principle of using simpler, more economical components.
3Adaptability or versatility
If conventional mechanical systems are used for variable phase shifters, then phase shifting is achieved, but power handling capability is compromised
Solution Approach 1:
The patent replaces mechanical actuation systems with a thermo-electric actuator that uses thermal expansion of shape-memory alloy. This substitution creates a more robust actuation mechanism that can handle higher RF power levels without the mechanical wear, friction, and alignment issues that plague conventional mechanical phase shifters, thereby improving power handling capability.
4Adaptability or versatility
If conventional mechanical systems are used for variable phase shifters, then phase shifting is achieved, but passive intermodulation performance deteriorates
Solution Approach 1:
The patent replaces mechanical actuation systems with a thermo-electric actuator based on shape-memory alloy. This substitution eliminates mechanical contact points, sliding surfaces, and flexible cables that are sources of passive intermodulation. The solid-state thermal-mechanical actuation produces fewer spurious signals and intermodulation products, improving RF signal quality.
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 enables efficient remote electrical tilt operations with reduced size, cost, and complexity while maintaining high power handling and low passive intermodulation performance, improving the overall efficiency and effectiveness of base station antennas.
Implementation Method 1
the thermally-deformable component may have a first shape when heated by the actuator drive signal to a temperature above a threshold temperature and a second different shape when cooled to a temperature below the threshold temperature
Implementation Method 2
a thermo-electric actuator is also provided, which is configured to support remote electrical tilt (RET) operations within a BSA by mechanically actuating the variable length signal path in response to an actuator drive signal
Implementation Method 3
The SMA may be selected from a group consisting of Fe—Mn—Si, Cu—Zn—Al, Cu—Al—Ni and Ni—Ti alloys
Data Source
AI summary
Base station antennas (BSAs) include at least one feed signal phase shifter having a variable length signal path therein, which provides an adjustable signal delay in response to mechanical actuation thereof. A thermo-electric actuator is provided to support remote electrical tilt operations by mechanically actuating the variable length signal path in response to an actuator drive signal. The thermo-electric actuator may include thermally-deformable components, such as SMA springs and wax motors.