Radar Bracket Side Wall Destructive Interference
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Solution Overview
Problem
Modern vehicles equipped with radar systems face challenges in reducing unwanted echo signals, which can lead to misdetected targets and increased accident risk due to the sensitivity of radar receivers to noise and spurious echoes.
Innovation Solution
A radar bracket with a central portion for housing the radar module and a side wall made of non-conductive material, where the backside is covered with a radar absorbing material having a specific dielectric constant and thickness to minimize reflections, utilizing the concept of a reflectionless slab to cancel out echo signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radar absorbing material is used to reduce unwanted echo signals, then the reliability of radar system is improved, but the amount of reflected echo signals from the radar absorbing material itself increases due to high dielectric constant
Solution Approach 1:
A non-conductive side wall with specific thickness is introduced as an intermediary layer between the radar absorbing material and the external environment. This side wall acts as a mediator that cancels out the harmful reflections from the radar absorbing material through destructive interference, while allowing the radar absorbing material to continue reducing unwanted echo signals.
Solution Approach 2:
The thickness of the non-conductive side wall is precisely controlled to be an odd multiple of one-quarter of the radar wavelength. This parameter change enables the reflections from the front and back surfaces of the side wall to be out of phase by 180 degrees, causing destructive interference that cancels the harmful reflected echoes.
2Loss of energy
If radar absorbing material with high dielectric constant is applied to reduce echoes, then the absorption of unwanted signals is improved, but the reflection at the interface between air and radar absorbing material increases
Solution Approach 1:
The non-conductive side wall serves as an intermediary layer that reduces the abrupt dielectric constant change at the air-radar absorbing material interface. By positioning the radar absorbing material behind this side wall, the harmful interface reflections are cancelled through destructive interference while the energy absorption function is preserved.
Solution Approach 2:
The radar bracket employs a composite structure combining non-conductive material (side wall) with radar absorbing material. This composite arrangement allows the system to simultaneously achieve low reflection characteristics from the non-conductive material and high absorption characteristics from the radar absorbing material, resolving the contradiction between absorption and reflection.
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 radar bracket effectively reduces secondary echo signals reflected from the vehicle, minimizing interference and enhancing the reliability of radar systems by achieving a 10dB reduction in signal strength, thereby improving the accuracy of radar detection.
Implementation Method 1
at least of a portion of a backside of the side wall is covered by a radar absorbing material having a dielectric constant higher than a dielectric constant of the side wall
Implementation Method 2
the portion of the side wall being covered by the radar absorbing material has a thickness d w defined as where λ 0 is the wavelength in air of a center frequency of the radar module
Data Source
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Figure 3a~3b
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AI summary
The invention relates to a radar bracket (300) for a vehicle (100) comprising: a central portion configured to receive a radar module (302) so that said radar module is exposed on a front side of said radar bracket; a side wall (304) encircling and extending laterally from the central portion, the side wall comprising a non-conductive material; wherein at least of a portion of a backside of the side wall is covered by a radar absorbing material (504) having a dielectric constant higher than a dielectric constant of the side wall, the backside of the side wall being configured to face the vehicle, and wherein the portion of the side wall being covered by the radar absorbing material has a thickness dw proportional to a quarter of the wavelength of the signal emitted by the radar module, and selected based on the dielectric constants of the side walls of the radar bracket and the radar absorbing material, such that a reflection at the interface between the side wall and the radar absorbing material is effectively cancelled out.