In-Cabin Radar Antenna Layout for Low-Coupling Beam Control
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Solution Overview
Problem
In-cabin radar apparatuses face challenges with direct coupling between transmitting and receiving antennas due to miniaturization, leading to issues with beam distribution and detection performance, particularly in forming a virtual array pattern corresponding to the vehicle space.
Innovation Solution
The configuration involves disposing transmitting antennas vertically and receiving antennas horizontally, with each antenna connected by perpendicularly oriented feed lines, and incorporating electromagnetic band gap (EBG) patterns to reduce direct coupling and improve impedance matching, thereby optimizing beam distribution and detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the in-cabin radar apparatus is miniaturized, then the apparatus size is reduced, but direct coupling between transmitting and receiving antennas occurs causing beam distribution degradation
Solution Approach 1:
A ground structure is introduced as an intermediary element between the transmitting and receiving antennas. This ground structure acts as a mediator to control electromagnetic field distribution, prevent direct coupling between antennas, and maintain proper beam distribution patterns even in the miniaturized apparatus configuration
Solution Approach 2:
The patent utilizes the vertical dimension by positioning the transmitting and receiving antennas at different heights above the ground structure. This dimensional separation allows the antennas to be closely spaced in the horizontal plane (enabling miniaturization) while maintaining adequate electromagnetic isolation through the vertical ground structure
2Area of stationary object
If transmitting and receiving antennas are disposed close together, then the apparatus footprint is reduced, but grating lobes are generated reducing detection accuracy
Solution Approach 1:
The ground structure serves as an intermediary that controls the electromagnetic interaction between closely spaced transmitting and receiving antennas. It suppresses grating lobe formation by managing the field distribution in the region between antennas, enabling compact footprint while maintaining detection precision
Solution Approach 2:
The patent optimizes the spacing between transmitting and receiving antennas to be less than or equal to half of the transmitting and receiving wavelength. This parameter control, combined with the ground structure, prevents grating lobe generation while maintaining a compact apparatus footprint
3Volume of moving object
If antenna spacing is reduced for miniaturization, then the apparatus size is reduced, but virtual array pattern formation is compromised
Solution Approach 1:
The ground structure acts as a mediator that enables the formation of correct virtual array patterns even when antennas are closely spaced. It controls the electromagnetic field distribution to ensure that the virtual array pattern corresponds accurately to the physical vehicle space, despite the reduced antenna spacing required for miniaturization
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 configuration enhances detection performance by minimizing grating lobes and optimizing beam distribution to correspond with the vehicle space, improving the sensitivity and accuracy of passenger detection and monitoring.
Implementation Method 1
a large area electromagnetic band gap (EBG) pattern installed between disposed transmitting antennas and disposed receiving antennas and having a high impedance characteristic in a transmitting and receiving frequency band
Implementation Method 2
transmission side feed lines and receiving side feed lines may be implemented in coplanar waveguide forms
Data Source
AI summary
In an in-cabin radar apparatus, transmitting antennas are disposed at one side in a direction parallel to a control circuit and disposed in a line in a vertical direction, and receiving antennas are disposed at one side in a direction perpendicular to the control unit and disposed in a line in a horizontal direction. Each transmission side feed line may be perpendicularly connected to one of the transmitting antennas, and each receiving side feed line may be perpendicularly connected to one of the receiving antennas. Each of a distance between the transmitting antennas and a distance between the receiving antennas may be implemented to be less than or equal to half of a transmitting and receiving wavelength.