In this article, we proposed a harmonic-absorbed frequency selective rasorber (HA-FSR). It consists of a non-resonant frequency selective surface (FSS) with inductive square loops, capacitive patches, and resistive sheet-based absorbers. The non-resonant FSS is of harmonic-suppression (HS) feature, which is free of spurious harmonic transmission bands up to three octaves of the main passband. We introduced resistive sheets on both sides of the HS-FSS to perform wideband absorption. Full-wave simulated and measured results both show that the proposed HA-FSR owns main passband with -3-dB bandwidth of 3 GHz at the X-band and -10-dB absorption band from 20 to 30 GHz. The frequency range of harmonic-absorption covers from around two to three octaves of the passband. The proposed HA-FSR can be applied in electromagnetic (EM) shielding and low-observable platforms.

The structural and electronic properties of graphene/graphene-like Aluminum Nitrides monolayer (Gr/g-AlN) heterojunction with and without vacancies are systematically investigated by first-principles calculation. The results prove that Gr/g-AlN with nitrogen-vacancy (Gr/g-AlN-V_N) is energy favorable with the smallest sublayer distance and binding energy. Gr/g-AlN-V_N is nonmagnetic, like that in the pristine Gr/g-AlN structure, but it is different from the situation of g-AlN-V_N, where a magnetic moment of 1 μ_B is observed. The metallic graphene acts as an electron acceptor in the Gr/g-AlN-V_N and donor in Gr/g-AlN and Gr/g-AlN-V_Al contacts. Schottky barrier height ${\Phi }_{\mathrm{B},\mathrm{n}}$ by traditional (hybrid) functional of Gr/g-AlN, Gr/g-AlN-V_Al, and Gr/g-AlN-V_N are calculated as 2.35 (3.69), 2.77 (3.23), and 1.10 (0.98) eV, respectively, showing that vacancies can effectively modulate the Schottky barrier height. Additionally, the biaxial strain engineering is conducted to modulate the heterojunction contact properties. The pristine Gr/g-AlN, which is a p-type Schottky contact under strain-free condition, would transform to an n-type contact when 10% compressive strain is applied. Ohmic contact is formed under a larger tensile strain. Furthermore, 7.5% tensile strain would tune the Gr/g-AlN-V_N from n-type to p-type contact. These plentiful tunable natures would provide valuable guidance in fabricating nanoelectronics devices based on Gr/g-AlN heterojunctions.

A harmonic suppressed (HS) frequency selective rasorber (FSR) based on square loops resonators and resistive-film sheets is presented in this paper. The frequency selective rasorber is designed by cascading the band pass FSS and broadband absorber together which owns a main pass band at center frequency of 8GHz, with harmonic transmission windows suppressed and out-of-band reflection absorbed from 12GHz to 26GHz. Lossless FSS with band pass response and lossy absorber with broadband absorption are analyzed by equivalent circuit model respectively. The frequency range of harmonic suppression covers three octaves of main pass band frequency. Besides, the measured results agree well with the simulated ones. The proposed harmonic suppressed FSR could be used as radome in enhancing anti-interference performance of wireless communication system and improving stealth performance of radar platform.

In this Letter, we present a cylindrical conformal holographic impedance metasurface for orbital angular momentum (OAM) generation. The conformal holographic metasurface is designed by establishing the element library and deducing the formula of holographic tensor impedance modulation. The feasibility of the scheme is verified by simulations and experiments. Simulated and experimental results are in good agreement with theoretical analysis. The results show that OAM vortex wave energy can be generated efficiently by a cylindrical conformal impedance metasurface, which can provide a reference for OAM communication and vortex radars with conformal devices.

In this letter, we design a magnetically coupled resonant wireless power transfer (MCR-WPT) system on the conformal cylindrical surface based on the flexible printed circuit (FPC) coils. The coil has the advantages of small size, lightweight, and high bendability. We combine mathematics and simulations to explore the relationship between the self-inductance/mutual inductance of the flexible coil and the bending radius of the conformal cylindrical surface. Both theoretical and simulation results show that as the bending radius decreases linearly, the self-inductance and mutual inductance of the coil also decrease nonlinearly. In addition, as the bending radius decreases, the transmission efficiency (TE) decreases, and the resonant frequency shifts to a higher range. Finally, measured and simulated results agree well, which further validates the conclusions.