RF Tag Direction Detection Using Antenna Directivity Control
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Solution Overview
Problem
Conventional radio-frequency tag communication devices face challenges in accurately detecting the direction of a communication object with high resolution and stability, especially when the device's attitude changes, and they tend to be large due to the need for multiple antenna elements to narrow the main lobe's angular range.
Innovation Solution
A radio-frequency device with a receiver antenna system that includes a reception-directivity control portion, a received-signal-strength detecting portion, and a direction detecting portion, which controls the directivity of reception based on the strength of signals in first and second maximum-reception-directivity directions to accurately determine the direction of the communication object, and a radio-frequency tag communication device with an attitude sensor to adjust directivity regardless of the device's attitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple antenna elements are used to narrow the main lobe's angular range, then direction detection resolution is improved, but device size increases
Solution Approach 1:
The patent changes the parameter of antenna element spacing to achieve narrow main lobe angular range with fewer elements. By optimizing the spacing between antenna elements (making it larger than conventional designs), the main lobe becomes narrower, improving direction detection resolution without requiring multiple closely-spaced elements, thus reducing device size.
2Productivity
If conventional BFA processing is used for directional detection, then calculation amount is reduced, but detection resolution becomes low
Solution Approach 1:
The patent performs preliminary action by pre-calculating and storing optimal weight values for different directions in a lookup table. During operation, the system simply retrieves the appropriate weight values based on the detected direction, avoiding complex real-time calculations while achieving high-resolution direction detection through the optimized antenna element spacing and weight application.
3Device complexity
If directivity control is not adjusted for device attitude changes, then device complexity is reduced, but communication stability deteriorates
Solution Approach 1:
The patent implements feedback by using an attitude sensor to detect device orientation changes and automatically adjusting the directivity control parameters accordingly. The detected attitude information feeds back to the directivity control unit, which modifies the beam forming weights to maintain optimal communication direction, ensuring stable communication without requiring complex manual intervention or overly sophisticated control algorithms.
Data Source
AI summary
A radio-frequency device includes a PAA processing portion configured to control a directivity of reception of a receiver antenna device, a received-signal-strength detecting portion configured to detect a strength of the received signal received by the receiver antenna device, and a direction detecting portion configured to detect the direction toward the communication object, on the basis of a direction in which a higher one of two strength values of the received signal respectively detected in first and second maximum-reception-directivity directions of a predetermined angular difference established by the PAA processing portion is minimal. Accordingly, the direction toward the radio-frequency tag can be suitably detected.