Rat-Race Coupled Antenna Layout for Precise Indoor Positioning
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Solution Overview
Problem
Current positioning systems, such as GPS and WiFi-based methods, face challenges in achieving high accuracy, especially in indoor environments and with small, low-directivity antenna structures, which are not effective for high-precision positioning.
Innovation Solution
An antenna device with a simple structure and low cost, integrating planar antennas and a rat-race coupler, which generates sum and difference patterns to calculate incident angles using signal strength ratios, allowing for miniaturization and high-precision positioning without phase measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS or WiFi-based positioning methods are used, then positioning coverage is achieved, but positioning accuracy deteriorates to 3-5 meters or more
Solution Approach 1:
The system divides the positioning task into multiple receivers distributed across the target area, each independently measuring signal parameters. This segmentation enables higher accuracy through spatial distribution without requiring a single complex centralized system.
Solution Approach 2:
The patent replaces traditional phase-based measurement systems with a mechanical/signal-strength-based approach using sum and difference patterns. This substitution simplifies the system while achieving high accuracy through amplitude ratios rather than complex phase measurements.
2Volume of moving object
If small, flat antenna structures are used to reduce device volume, then device size is reduced, but positioning accuracy deteriorates due to low directivity
Solution Approach 1:
The patent merges two antennas with a rat-race coupler into a single integrated structure that produces sum and difference patterns. This combination achieves high directivity equivalent to larger antennas while maintaining a compact form factor suitable for small devices.
Solution Approach 2:
The system transitions from relying on single-antenna directivity to using the spatial dimension of multiple antennas arranged in a specific geometry. This dimensional approach enables high accuracy through pattern formation rather than individual antenna directivity.
3Measurement precision
If high-precision positioning is achieved through complex antenna structures, then positioning accuracy is improved, but manufacturing cost and complexity increase
Solution Approach 1:
The rat-race coupler serves multiple functions simultaneously: it combines signals from two antennas, generates sum and difference patterns, and provides impedance transformation. This multi-functionality reduces the need for additional components, simplifying manufacturing while achieving high precision.
Solution Approach 2:
The system changes the operating parameters by using amplitude ratios of sum and difference patterns instead of traditional phase measurements. This parameter change simplifies the manufacturing requirements while maintaining high positioning accuracy through alternative measurement physics.
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 achieves an average positioning error of 2 km, which is 2% of the area's length or width, improving angle accuracy and overcoming symmetry issues in pattern determination, while simplifying the antenna architecture and reducing costs.
Implementation Method 1
the coupler has a first input terminal, a second input terminal, a difference output terminal and a sum output terminal. The first input terminal is connected to the first antenna through the first feeding point, and the second input terminal is connected to the second antenna through the second feeding point.
Data Source
AI summary
An antenna device, a positioning system and a positioning method are provided. The positioning method includes: dispersedly arranging a plurality of receivers to form a target area, in which each of the receivers includes the antenna device; receiving a wireless signal from the target area through the antenna device, and generating a difference signal strength and a sum signal strength; calculating, for each of the receivers, a sum-difference ratio between the difference signal strength and the sum signal strength, and estimating a corresponding one of estimated incident angles according to the sum-difference ratio and a comparison table; executing, in response to obtaining the estimated incident angles corresponding to the receivers, a positioning algorithm according to the estimated incident angles, so as to generate a plurality of possible positions; and executing an optimization algorithm to calculate a best estimated position of the possible positions.