The infrared spectral emissivity of selective radiators varies with wavelength. Selective radiators have good application prospects in solar energy utilization, camouflage, radiation refrigeration and other fields. In this paper, a selective radiator which has low emissivity in mid-far infrared band is designed by using frequency selective surface. The electromagnetic characteristics of the selective radiator in mid-far infrared band are calculated by using HFSS simulation software. Through calculation, it is found that the designed selective radiator has high reflectivity and low transmittance for the incident electromagnetic wave at 3-14μm band. In this paper, the reflection and transmission characteristics of the selective radiator to electromagnetic wave were calculated at three incident angles of 0o, 15o and 30o. The calculated results show that with the increase of incident Angle, the band stop filter bandwidth of the selective radiator increases, and the resonant wavelength moves to the short-wave direction, but the variation range is not large. The filtering characteristics of bands above 6μm show better band resistance with the increase of incidence Angle.
Artificially synthesized electromagnetic metamaterials can realize the unique properties that are not possessed by natural media in nature, and have broad application prospects in related fields. The zero-refractive index metamaterial is a metamaterial whose relative permittivity or relative permeability is zero through artificial design. It has infinite wavelength, uniform field effect, high directivity radiation, wavefront control and other properties. This paper theoretically analyzes the influence of the structural parameters of the material on the transmission coefficient, and uses software to simulate the electric field distribution of electromagnetic waves passing through the material. The transmission phenomena of single zero and double zero refractive index metamaterials are numerically simulated, and the reasons for this phenomenon are explained. The research results can be used in optical device design and civilian related fields.
The spectral emissivity of the surface of the selective Radiator varies with the wavelength. The selective radiator can be prepared by periodic structure, which has strange electromagnetic characteristics. HFSS software is used to construct the frequency selection surface based on periodic structure. The structural material is metal gold, the dielectric layer material is silicon dioxide, and the resonance unit parameters are in the micron scale. The modulation characteristics of the electromagnetic wave transmittance in the infrared band are calculated. Through calculation, it is found that the designed selective radiators have very low emissivity on both the mid-infrared 3-5mm atmospheric window and far-infrared 8- 14mm atmospheric window. The resonant central frequency point in the mid-infrared atmosphere window moves from 4.6mm to 4.9mm.In the mid-infrared 3.33 -6.17mm band, transmission rate is below 0.1. In the far-infrared 7.43 -12.2mm band, transmission rate is lower than 0.1.The influence of the structure on the electromagnetic transmission characteristics is recalculated by changing the thickness of the dielectric layer. It is found that the thickness of the dielectric layer has little influence on the resonance center of low transmittance, and the influence is mainly on the bandwidth and the peak value of high transmittance. A change in the dielectric layer's dielectric constant will also cause a change in the position of the resonant frequency. When the dielectric constant increases from ε= 2.9 to ε=5.9, the location of the resonant frequency changed obviously. The resonant wavelength in the far-infrared atmospheric window moves from 8.72mm to 11.36mm. As the dielectric constant increases, the resonant wavelength moves towards the long wave.
Artificially synthesized electromagnetic metamaterials can realize the unique properties that are not possessed by natural media in nature, and have broad application prospects in related fields. The zero-refractive index metamaterial is a metamaterial whose relative permittivity or relative permeability is zero through artificial design. It has infinite wavelength, uniform field effect, high directivity radiation, wavefront control and other properties. This paper theoretically analyzes the influence of the structural parameters of the material on the transmission coefficient, and uses software to simulate the electric field distribution of electromagnetic waves passing through the material. The transmission phenomena of single zero and double zero refractive index metamaterials are numerically simulated, and the reasons for this phenomenon are explained. The research results can be used in optical device design and civilian related fields.
The spectral emissivity of the surface of the selective radiation body changes with the change of wavelength. Selective infrared radiator is designed based on frequency selective surface theory. Selective radiators can be achieved using periodic structures, which has the peculiar electromagnetic properties, and has a good regulating effect on the transmission of electromagnetic wave by scientific and reasonable design. Using HFSS software, a frequency selection surface based on periodic single-screen ring was constructed. The ring was made of metallic gold, the dielectric layer was made of silicon dioxide, and the parameters of the basic unit were in the order of micron. The modulation characteristics of electromagnetic wave transmittance of the surface in the infrared band are calculated. It is found that the designed selective radiator has an emissivity of less than 0.1 in the 6.44-10 micrometer band. It is found that with the increase of the interval, the bandwidth of the low transmittance at the long wave becomes narrow. If the inside diameter of the ring is kept unchanged, the outside diameter of the ring is increased. As the width of the ring increases, the resonance frequency of the electromagnetic wave at the long wave decreases and the bandwidth of the low emissivity increases. As the width of the ring decreases, the resonance frequency of electromagnetic wave moves from high frequency to low frequency and the bandwidth of low emissivity decreases. Bandwidth with a transmittance of less than 10% varies from 17.6THz to 16.6 THz. Finally, the application of selective radiator is discussed.
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