Da Yi

A Novel Tunable Absorber Based on Vertical Graphene Strips

A novel type of graphene strips based three-dimensional absorber is proposed, which shows a dynamic tunability of absorbing band. The proposed structure is based on a two-dimensional array of vertical graphene strips with dielectric substrates beneath them. An absorption peak is obtained at the plasmon resonant frequency of the graphene strips. The relationship between the plasmon resonant frequency and the dimensions of absorber obeys the scaling law. Furthermore, by using the trapezoid graphene strips together with the hybrid electrostatic biases, the absorbing bandwidth can be improved significantly. In addition, the absorber shows a good stability with various incident angles and polarizations.

Tunable Microwave Absorber Based on Patterned Graphene

Two approaches to realize a tunable absorber based on patterned graphene metasurface are proposed in this paper. In the first approach, different from available absorption amplitude tunable absorbers, the center frequency of the absorber can be tuned by the surface resistance of the graphene in a wide range while maintaining a large absorption coefficient. The second approach, by implying the stack of graphene as the absorbing layer, can introduce a remarkable shift of the center frequency. These two approaches are theoretically illustrated using equivalent circuits and 3-D full wave simulation. Samples that are optically transparent are also fabricated and measured in a rectangular waveguide. A good correlation between simulation and measurement results is obtained.

Experimental demonstration of transparent microwave absorber based on graphene

A novel transparent microwave absorber is proposed in this paper. Fluorine-doped tin oxide glass, glass and monolayer graphene are applied as the reflector layer, substrate and absorbing layer respectively to form a Salisbury absorber. The performance of the absorber is measured by the rectangular waveguide. An improved equivalent circuit model is proposed to analyze the transparent absorber. There is a good correlation between absorption coefficients obtained from the equivalent circuit model, 3-D full wave simulation and measurement. As high as 95% incident power can be absorbed by using the proposed absorber.

Transparent Microwave Absorber Based on Patterned Graphene: Design, Measurement, and Enhancement

A patterned graphene-based transparent microwave absorber is proposed in this paper. Graphene is transferred onto polyethylene terephthalate (PET) film, and patterned as μm-level periodic patches, so that a capacitive and resistive graphene surface is obtained at microwave band. By placing this graphene/PET film on the top of a glass substrate and applying fluorine-doped tin oxide film as the reflective layer, transparent absorber working at Ku band is realized. The optical transmittance of the fabricated graphene/PET film reaches around 80% in the whole optical light range, while the absorption coefficient reaches 90% at 12.6 GHz. By analyzing the parasitic effects in the rectangular waveguide measurement, a good agreement is obtained among the measurement, three-dimensional full-wave simulation, and the equivalent circuit. Two configurations are further analyzed to enhance the absorption level and the working bandwidth of the absorber. 100% absorption and 3 GHz bandwidth broadening are realized.

Graphene-silicon diode loaded patch antenna

In this paper, we proposed a graphene-silicon diode loaded patch antenna, which is fabricated on silicon wafer. The structure of patch antenna is perfectly compatible with the diode process. Its equivalent circuit and frequency-tunable characteristics are analyzed with an equivalent circuit model. The result is verified by 3-D full-wave simulation. This patch antenna, which is directly printed on silicon wafer, finds a potential application of graphene in GHz frequency band and can be easily integrated with other integrated circuits.

Transparent microwave absorber based on single layer graphene film

High quality single layer graphene grown by chemical vapor deposition (CVD) method has sheet impedance ranging from 300 ohm to 600 ohm. We demonstrate that it can be used as an absorbing film in Salisbury absorber. An efficient and accurate transmission line model is proposed for such transparent graphene film absorber at 38.5 GHz. Result of transmission line model is in good agreement with that of the 3D full-wave simulation. Finally, the sample of the graphene absorber is fabricated, and an easy-to-use testing method based on pyramidal horn antenna is proposed to characterize the absorbing property of the absorber sample.

Signal transmission along Cu-graphene heterogeneous interconnects

This paper analyzes and compares the frequency responses of both Cu based interconnect and heterogeneous interconnect which consists of graphene sheets and Cu. By using partial element equivalent circuit (PEEC) method, the equivalent electric parameters of these two kinds of interconnects are obtained. A driver-interconnect-load (DIL) model and an equivalent single conductor (ESC) circuit are utilized to study the performances of the heterogeneous interconnect in different conditions. The heterogeneous interconnect shows advantages over the traditional Cu based interconnect.

A novel three dimensional tunable frequency selective surface based on graphene micro-ribbons

A novel type of three-dimensional (3D) frequency-selective surface (FSS) based on vertical graphene micro-ribbons is demonstrated to realize dynamic tunability of the frequency selectivity. The proposed structure is based on a two-dimensional array of vertical graphene micro-ribbons which are printed on the dielectric substrates with metallic ground planes placed at the bottom. A transmission line model of the proposed FSS is introduced. Additionally, according to the scaling law, the transmission zero frequency can be predicted rapidly and accurately. Based on the combination of the equivalent circuit model and scaling law, the transmission property of the FSS structure is analyzed. Finally, the effect of geometrical parameters on the performance of the FSS is studied.