Tunable Impedance of Cobalt Loaded Carbon for Wide-Range Electromagnetic Wave Absorption
Xiaonong Wang1, Zhongliao Wang2, Dawei Xi3
1College of Electronic Engineering, National University of Defense Technology, Hefei, Anhui, 230037, P. R. China.
Abstract:
Impedance matching modulation of the electromagnetic wave (EMW) absorbers toward broad effective absorption bandwidth (EAB) is the ultimate aim in EMW attenuation applications. Here, a Joule heating strategy is reported for preparation of the Co-loaded carbon (Co/C) absorber with tunable impedance characteristics. Typically, the size of the Co can be regulated to range from single-atoms to clusters, and to nanocrystals. The varied sizes of the Co combined with different graphitization degrees of carbon can result in different relative input impedances and electromagnetic loss, leading to the tunable EMW absorption properties of the Co/C absorber. By meticulously coalescing the different prepared Co/C, the working frequency can be easily tuned, covering Ku, X, and C bands. Furthermore, the Co/C demonstrates a high EMW attenuation due to its unique dielectric loss capability and magnetic loss characteristics. The abundant interfaces of Co/C can also contribute to the enhanced interfacial polarization for improving EMW attenuation. This work demonstrates the importance of optimizing the metal and carbon interaction to the impedance matching toward wide EAB of the EMW absorbers.
Related Concept Videos
Colors and Magnetism
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
Mesh Analysis for AC Circuits
The process of harmonizing these impedances begins with a clear understanding of the input and output signals. Once these signals are known, the...
Electromagnetic Wave Equation
However, although electric and magnetic fields were first introduced as mathematical constructs to simplify the description of mutual forces between charges, a natural question emerges from Maxwell's equations:...
Equivalent Capacitance
The following strategies are adopted to calculate...
Inductance: Solid Cylindrical Conductor
Given the uniform current distribution, the magnetic field Hx and flux density Bx inside the conductor are...
Susceptibility, Permittivity and Dielectric Constant


