Radio-wave Transmitting Substrate with Segmented Heat-ray Reflection Film
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Solution Overview
Problem
Conventional substrates with infrared-reflecting functions have insufficient transparency to radio waves in the frequency range of several hundred megahertz to tens of gigahertz, which is necessary for modern mobile communication systems like 4G and 5G.
Innovation Solution
A radio-wave transmitting substrate is designed with a dielectric substrate and a heat-ray reflection film, featuring specific geometric and material configurations that optimize radio-wave transmission, including a radio-wave transmitting region where the electroconductive film is absent, and a heat-ray reflection film with layers like metal oxides and nitrides, ensuring low radio-wave transmission loss and high solar reflectance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a continuous heat-ray reflection film including metal is formed on the substrate, then infrared reflection performance is improved, but radio-wave transmission transparency deteriorates at frequencies of several hundred megahertz to tens of gigahertz
Solution Approach 1:
The continuous heat-ray reflection film is divided into multiple discrete segments or islands, rather than forming a complete continuous layer. This segmentation allows radio waves to pass through the gaps between segments while the metal segments still provide sufficient infrared reflection when viewed from the direction of incidence
Solution Approach 2:
Different regions of the substrate surface are given different properties: regions with heat-ray reflection film provide infrared reflection, while regions with openings provide radio-wave transmission. The local configuration of film segments and gaps is optimized to simultaneously satisfy both infrared reflection and radio-wave transmission requirements in their respective functional zones
2Object-affected harmful factors
If the heat-ray reflection film coverage is increased to improve infrared reflection, then heat-shielding performance is improved, but radio-wave transmission loss increases
Solution Approach 1:
Instead of forming a complete continuous film that would provide maximum infrared reflection but block radio waves, only a partial coverage of the substrate surface with metal segments is applied. This partial action provides sufficient infrared reflection performance while maintaining adequate radio-wave transmission by leaving gaps between the metal segments
Solution Approach 2:
The physical parameters of the heat-ray reflection film are changed: instead of a continuous layer with 100% coverage, discrete segments with controlled coverage ratios (e.g., 30-70% coverage) are used. The segment size, shape, spacing, and coverage ratio are optimized to balance infrared reflection and radio-wave transmission performance
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 substrate achieves excellent transparency to radio waves across the required frequency range with minimal transmission loss, while maintaining effective heat-ray reflection properties, enhancing both radio-wave transmission and heat-shielding capabilities.
Implementation Method 1
impart the function of reflecting infrared rays (heat rays) to the windows of vehicles, buildings, etc. to thereby reduce the intake of heat from sunlight
Implementation Method 2
the substrate is required to further have high transparency to radio waves having given frequencies
Data Source
AI summary
A radio-wave transmitting substrate includes a dielectric substrate, and, on at least one main surface of the dielectric substrate, a heat-ray reflection film including an electroconductive film, and an opening where the electroconductive film is absent in a plan view. At least a part of the at least one main surface in a plan view is a radio-wave transmitting region. The radio-wave transmitting region is a region where every 1-cm square unit region in the region satisfies the following expression (a): L>802.6×S−503.7. L is an overall length (unit: mm/cm2) of a boundary between the heat-ray reflection film and the opening in the unit region, and S is a proportion of an area occupied by the heat-ray reflection film in the unit region.