In this research, we have designed a hybrid metamaterial absorber (HMA) based magnetic material from C to the Ku-band. The magnetic material was prepared by the ball milling method with differences in the mass ratio of the FeCo alloy to C. The HMA structure consists of four layers: FeCo–C, metallic structure (two punched-in rings with four L-shape in the edges), dielectric (FR-4), and continuous metallic layer. The widest absorption spectrum of structure based FeCo–C (75%C) in a frequency range of 6.9–16.8 GHz with absorption exceeding 90%. The absorption mechanism has also been carefully analyzed through the distribution of surface current and power loss density. These findings may advance the design of devices leveraging metamaterials, including applications in stealth radar technology, electromagnetic shielding for health and safety, and reduction of electromagnetic interference for high-performance electronic and communication systems.

This study presents a tri-layer broadband metamaterial absorber that operates in the GHz range. The absorber was composed of a polyhedral iron-cobalt alloy/graphite nanosheet material arranged in a flat sheet with two punched-in rings for the top layer, a continuous FR-4 layer at the middle, and a continuous copper layer at the bottom. For the normal incidence of the electromagnetic wave, the proposed absorber demonstrated an exceptional broadband absorption in a frequency range of 7.9–14.6 GHz, revealing an absorption exceeding 90%. The absorption magnitude remains to be above 90% in a frequency range of 8–11.1 GHz for transverse-electric-polarized waves at incident angles up to 55°. For both the transverse-magnetic- and electric-polarized waves, the absorption exceeds 90% in a frequency range of 9.5–14.6 GHz. The physical mechanism behind the absorption properties is analyzed thoroughly through the electric and magnetic field distributions. The obtained results could contribute potentially to the development of microwave applications based on metamaterial absorbers, such as radar-stealth technology, electromagnetic shielding for health safety, and reduced electromagnetic interferences for high-performance communications and electronic devices.

This study presents a tri-layer broadband metamaterial absorber which operates in the GHz range. The absorber was composed of a polyhedral iron-cobalt alloy/graphite nanosheet material arranged in a flat sheet with two punched-in rings for the top layer, a continuous FR-4 layer at the middle, and a continuous copper layer at the bottom. For the normal incidence of electromagnetic wave, the proposed absorber demonstrated an exceptional broadband absorption in a frequency range of 7.9-14.6 GHz, revealing an absorption exceeding 90%. The absorption magnitude remains to be above 90% in a frequency range of 8-11.1 GHz for transverse-electric-polarized waves at incident angles up to 55°. For both transverse-magnetic- and electric-polarized waves, the absorption exceeds 90% in a frequency range of 9.5-14.6 GHz. The physical mechanism behind the absorption properties is analyzed thoroughly through the electric- and magnetic-field distributions. The obtained results could contribute potentially to the development of microwave applications based on metamaterial absorbers, such as radar-stealth technology, electromagnetic shielding for health safety and reduced electromagnetic interferences for high-performance communications and electronic devices.

Trong nghiên cứu này, chúng tôi đã thiết kế một cấu trúc vật liệu biến hóa hấp thụ sóng điện từ lai (HM-MA) dựa trên vật liệu ferrite hoạt động trong dải tần Ku. Vật liệu ferrite được chế tạo bằng phương pháp nghiền bi từ vật liệu NiO, ZnO và Fe2O3. Cấu trúc HM-MA gồm bốn lớp: lớp Ni0.5Zn0.5Fe2O4, cấu trúc kim loại (gồm hai vòng tròn đục lỗ và bốn hình chữ L ở các góc), lớp điện môi (FR-4), và lớp kim loại liên tục. Cấu trúc sử dụng vật liệu Ni0.5Zn0.5Fe2O4 cho phổ hấp thụ cực đại là 75%. Tuy nhiên, dưới tác động của từ trường ngoài lên tới 2000 Oe, cường độ hấp thụ của cấu trúc được tăng thêm 22%. Cơ chế hấp thụ ở 0 Oe cũng đã được phân tích chi tiết thông qua mật độ dòng điện bề mặt và phân bố mật độ tổn hao năng lượng. Những kết quả này góp phần mở rộng các ứng dụng thực tế của vật liệu biến hóa, bao gồm cả công nghệ tàng hình radar.