Radar Antenna Beam Pattern Segmentation for Ghost Elimination
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Solution Overview
Problem
Radar apparatuses using electronic scan methods face inaccuracies in detecting target angles due to phase differences exceeding 180°, leading to incorrect angle estimations and reduced resolution capabilities when trying to differentiate between correct and incorrect targets.
Innovation Solution
The radar apparatus employs two transmission antennae with different beam patterns, allowing for the determination of correct target detection by analyzing signal strengths across antennae, even with phase differences of 360° or greater, thereby improving accuracy by distinguishing between actual targets and phase folding ghosts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the interval of receiving antennae is narrowed to widen the detection angle range, then the angle detection range is improved, but interference between received electric waves is caused and phase power is reduced
Solution Approach 1:
The detection space is segmented into multiple regions (first region with wider angle range, second region with narrower angle range). Different antenna intervals are used for different spatial regions, allowing the system to achieve both wide coverage and high precision in different areas without compromising overall performance.
2Area of stationary object
If the transmitted electric wave beam is enlarged to detect targets beyond the traveling traffic lane, then the detection coverage is improved, but the ability to distinguish correct targets from obstacles beyond the lane is reduced
Solution Approach 1:
Different beam widths are applied to different spatial regions: a wider beam pattern is used for the first region (beyond the traveling traffic lane) to ensure coverage, while a narrower beam pattern is used for the second region (traveling traffic lane) to maintain high target discrimination accuracy. This local differentiation resolves the contradiction between coverage and precision.
3Device complexity
If phase difference detection is performed within ±180° range, then the detection process is simplified, but targets with phase differences of 360° or larger are erroneously detected
Solution Approach 1:
The system dynamically adjusts the beam width based on the detection region. When a target is detected in the first region (beyond the lane), the beam is widened to capture the target. When a target is detected in the second region (within the lane), the beam is narrowed to improve angle estimation accuracy and eliminate folding ghosts, thereby maintaining reliability without increasing overall system complexity.
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 approach enhances the radar's ability to accurately detect target positions and angles beyond the ±180° range, reducing erroneous detections and improving overall resolution and accuracy.
Implementation Method 1
an electrical wave is transmitted from an antenna provided to the own vehicle, a reflected wave, which is reflected from the target, is received by the antenna
Implementation Method 2
calculates an angle of the target (an angle indicating how much the target is deviated from the traveling direction of the own vehicle) from a phase difference between the obtained received electric waves
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
There is provided a radar apparatus of an electronic scan type configured to transmit an electric wave and calculate an angle of a target based on a phase difference of respective reception signals, thereby detecting a target position. An antenna unit transmits and receives the electric wave and provided with two transmission antennae. A transmission unit alternately transmits an electric wave having a first beam pattern and an electric wave having a second beam pattern from the two transmission antennae. First and second reception units calculate arrival angles and reception levels of reflected waves calculated from respective reception signals which are obtained by receiving the reflected waves by the first and second beam patterns. A comparison unit compares the reception levels by combining the arrival angles of the reflected waves. A determination unit determines whether a target actually exists at the arrival angles in accordance a comparison result.