Two-Antenna RF Angle-of-Arrival Detection Without Mirror Ambiguity
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Solution Overview
Problem
Existing angle of arrival (AoA) measurement systems using phase information from multiple antennas suffer from ambiguity issues, as signals from one side of the antenna axis cannot be distinguished from mirrored signals on the other side, and adding a third antenna to resolve this ambiguity incurs additional costs.
Innovation Solution
Using two antennas with different directional gain characteristics, where one antenna has higher gain on one side of the axis and the other antenna has higher gain on the opposite side, allowing for unambiguous AoA determination by considering both phase and signal strength differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a third antenna is added to resolve ambiguity, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent applies asymmetry by configuring the first antenna with a directional radiation pattern that provides different signal strengths for signals arriving from different sides of the antenna axis. This asymmetric gain distribution allows the system to distinguish between +α and -α angles without requiring symmetric three-antenna configurations, thereby resolving ambiguity while maintaining device simplicity.
2Measurement precision
If larger distance between antennas is used, then measurement precision is improved, but ambiguity increases
Solution Approach 1:
The patent introduces signal strength as an intermediary parameter that mediates between phase information and angle determination. By combining phase difference measurements with signal strength comparisons from the first antenna's directional pattern, the system can resolve ambiguity that would otherwise result from large antenna spacing, effectively using signal strength as a disambiguation mediator.
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
Enables unambiguous AoA determination without additional hardware, leveraging standard receiver circuitry to differentiate between signals from different sides of the antenna axis based on signal strength, thus resolving ambiguity at lower cost.
Implementation Method 1
Because of the distance between the antennas, a signal which is received will be correspondingly shifted in phase. This phase shift is depending on the angle corresponding to the direction of the incoming signal and the distance between the antennas.
Implementation Method 2
the first antenna having a larger gain than the second antenna for directions corresponding to one side of the antenna axis, the second antenna having a larger gain than the first antenna for directions corresponding to the other side of the antenna axis
Data Source
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AI summary
There is described a device for determining an angle of arrival of a received RF signal, the device comprising (a) a first antenna and a second antenna arranged with a predetermined distance between them on an antenna axis, the first antenna having a larger gain than the second antenna for directions corresponding to one side of the antenna axis, the second antenna having a larger gain than the first antenna for directions corresponding to the other side of the antenna axis, (b) receiver circuitry coupled to the first antenna and to the second antenna, the receiver circuitry being configured to determine a first phase and a first signal strength of a signal received by the first antenna and to determine a second phase and a second signal strength of a signal received by the second antenna, and (c) angle determining circuitry configured to determine the angle of arrival based on the first phase, the second phase, the first signal strength, and the second signal strength. There is also described a corresponding method, a computer program, and a computer program product.