Millimeter-Wave Radar Cover Material for Low-Loss 77 GHz Transmission
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Solution Overview
Problem
Conventional millimeter-wave radar covers lack sufficient transparency, especially at high frequencies, and fail to provide both high hardness and heat resistance, which are essential for advanced automotive and social infrastructure applications.
Innovation Solution
A thermoplastic resin composition containing an aromatic polycarbonate resin with a specific structural unit, optimized for a frequency range of 75 to 81 GHz, offering a relative dielectric constant of 3.0 or less, a dielectric loss tangent of 8.0×10−3 or less, and a loss factor of 17.0×10−3 or less, ensuring excellent millimeter-wave transparency and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resin materials (polybutylene terephthalate, polycarbonate, styrene-based resins) are used for millimeter-wave radar covers, then the covers can be manufactured with basic structural properties, but the millimeter-wave transparency is insufficient especially at high frequencies (76-81 GHz)
Solution Approach 1:
The patent uses a composite material consisting of polypropylene resin and ethylene-propylene-diene monomer rubber (EPDM) in specific proportions (EPDM content: 1-50 parts by mass per 100 parts of polypropylene). This composite achieves both high millimeter-wave transparency at 76-81 GHz and manufacturability, resolving the contradiction between transparency requirements and manufacturing flexibility.
2Reliability
If covers are made thinner to reduce millimeter-wave attenuation, then transparency improves, but mechanical strength and heat resistance deteriorate
Solution Approach 1:
The patent optimizes the compositional parameters of the resin mixture, specifically controlling the EPDM content within 1-50 parts by mass per 100 parts of polypropylene. This parameter optimization allows the cover to maintain adequate thickness for mechanical strength while achieving high millimeter-wave transparency through improved material properties.
3Measurement precision
If high-frequency millimeter waves (76-81 GHz) are used to increase detection distance and resolution, then radar performance improves, but transmission attenuation through conventional covers increases significantly
Solution Approach 1:
The patent employs a composite material of polypropylene and EPDM rubber that exhibits low dielectric loss at high frequencies. This composite material reduces transmission attenuation for 76-81 GHz millimeter waves while maintaining the detection performance benefits of high-frequency operation.
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 provides a millimeter-wave radar cover with minimal frequency-dependent transparency variation, high hardness, and excellent heat resistance, enhancing the performance of millimeter-wave radar modules across various applications, including automotive and medical uses.
Implementation Method 1
a cover for a millimeter-wave radar, the cover being provided on an antenna that transmits and/or receives a millimeter wave of 75 to 81 GHz
Implementation Method 2
the cover having a relative dielectric constant εr of 3.0 or less, a dielectric loss tangent tan δ of 8.0×10−3 or less
Implementation Method 3
excellent heat resistance
Data Source
AI summary
There is provided a cover for a millimeter-wave radar, the cover being provided on an antenna that transmits and/or receives a millimeter wave of 75 to 81 GHz, the cover containing a thermoplastic resin composition that contains an aromatic polycarbonate resin having a structural unit (A) represented by formula (1) below, the cover having a relative dielectric constant εr of 3.0 or less, a dielectric loss tangent tan δ of 8.0×10−3 or less, and a loss factor εr·tan δ of 17.0×10−3 or less:where in formula (1), R1 and R2 are each a hydrogen atom or a methyl group, and W1 is at least one selected from a single bond, an oxygen atom, a sulfur atom, and a divalent organic group.