A broadband metamaterial absorber with temperature scalability to 400 °C

Abstract

A broadband metamaterial absorber intended for applications at elevated temperatures was designed and fabricated. Its performance was measured over a temperature range from room temperature to approximately 400 °C. The absorber consists of a lossy resistive frequency selective surface (RFSS) on a dielectric substrate and a metallic ground plane with high-temperature stability scalable to approximately 400 °C. The top RFSS layer, made of conductive composites, was prepared using a mixture of graphite microflakes and water glass, and it showed good chemical and thermal stability up to 400 °C. Its sheet resistance was adjustable over a wide range with different proportions of graphite flakes and decreased gradually with increasing temperature. The metamaterial absorber demonstrated broadband absorption with a reflection coefficient of less than −10 dB in the X-band frequency range (8.2–12.4 GHz), resulting in the absorption of more than 90%. The influence of testing temperature on the reflection coefficient was correlated with the variation in the sheet resistance. The proposed metamaterial absorber is a promising candidate for use in high-temperature microwave absorption applications.

Multioctagonal Ring Metamaterial with Broadband Microwave Absorption at Elevated Temperature

“…EAB of recently reported high-temperature microwave absorbing metamaterials. [16][17][18][19][20][33][34][35][36][37] (AB: absolute bandwidth, RB relative bandwidth).…”

“…Because thermal stability has become the basis for further development of microwave absorption materials, especially in the aircraft, the nozzles, and nose cones of supersonic jets, some experts are researching high-temperature metamaterials, in hopes that metamaterials would still be found with broadband and strong absorption under high temperature. [14][15][16][17] Li et al used conductive TiB 2 squares as unit cells and obtained an absorptivity of more than 95% at an absorption frequency over a wide temperature range. [18] Shao et al designed a metamaterial absorbing coating with a dielectric loss layer of Al 2 O 3 and TiC and a metasurface of NiCrAlY that achieved RL < À5 dB at a frequency range of 8-12 GHz at 800 °C.…”

Lossy Frequency‐Selective Surface Metamaterials Based on Silicon Slice with Broadband Microwave Absorption at Elevated Temperature

“…[31] Qiao et al prepared a conductive paste by mixing graphite microflakes with sodium silicate and then printed a 0.01 mmthick square-ring FSS layer on the quartz glass using screen printing. They obtained an RL < À10 dB at 8.2-12.4 GHz at 400 C. [32] The absorption performance obtained in the aforementioned research for high-temperature EM metamaterials was worse than that for room-temperature materials; however, it provides guidance for other researchers in the exploration of wide-temperature absorbing materials.…”

“…They obtained an RL < −10 dB at 8.2–12.4 GHz at 400 °C. [ 32 ] The absorption performance obtained in the aforementioned research for high‐temperature EM metamaterials was worse than that for room‐temperature materials; however, it provides guidance for other researchers in the exploration of wide‐temperature absorbing materials.…”

High temperature microwave absorbing materials

“…8e). High temperature metamaterialbased square-loop-shape lossy resistive frequency selective surfaces (RFSSs) were simulated and prepared by Qiao et al 131 To prepare temperature-insensitive RFSS metamaterials, the dielectric constant of the matrix should be stable with increasing temperature. Quartz was chosen as the matrix, and the graphite flake was uniformly dispersed in water glass as the RFSS layer.…”