A new approach to design multi section wideband transmissive absorber using thin resistive sheets and dielectric slabs

A new design and analytical procedure are presented that greatly enhance the absorption bandwidth and absorptivity level with few dielectric layers without using the metallic ground plane. The performance of the proposed structure is beyond what is possible with Salisbury screen or Jaumann absorber. The performance improvement is obtained using the resistive sheets coated on the surface of each lossless dielectric slab. Reflected waves inside each dielectric layer are eliminated and input reflection coefficient can easily be written with the aid of binomial expansion without any approximation. So we can apply Binomial design and considerable improvement at the absorption level and bandwidth is realized by the selection of the resistive sheets with the critical resistivity values. Alternatively, we observed that transmission is independent from frequency and layer number and it can be controlled only by the initial and final layer's dielectric constants. Two cases are analyzed as air to air and air to dielectric. Absorptivity, transmittivity and reflectivity variations are presented versus frequency in 0–20 GHz band, in both cases. It is shown that choosing three layers backed with a final layer (εrb=20) structure in air to air case gives absorptivity greater than 90% in 5.45–14.55 GHz band where fractional bandwidth is 91% at 10 GHz design frequency. The design is performed at normal incidence and also wide angular stability at a reasonable level is presented. CST Microwave Studio and AWR simulation programs are also used to prove the correctness of the proposed method

Reflection and transmission properties of a graphene-dielectric-thin resistive layer structure in the THz range

We studied two-dimensional planar dielectric slab, sandwiched by graphene and thin resistive layer from two sides. Problem geometry is illuminated by a H-polarized electromagnetic plane wave from upper side. It is expected to observe the reflection and transmission performance of such a composite slab geometry depending on the electrical and geometrical parameters. We used the local reflection and transmission coefficients method to determine the overall performance. It is seen that the proper selection of the electrical resistivity of the thin resistive layer reduces the reflection from lower boundary of slab and the electrical thickness becomes less important for high THz range. Then, the geometry turns to be an air-dielectric interface. This is a novel finding and completely different from the pure dielectric slab without coatings which has frequency dependent characteristics. Also higher reflections are observed due to the higher conductivity of graphene in the low THz range. Furthermore, a sample finite plate is constructed in a same manner and it is modeled by using CST software. Presented method using equivalent 2D profile model and CST results are compared and very good consistency is observed. In both cases, the reflection can be controlled with the chemical potential at low THz range and the selection of the relative permittivity of the dielectric material determines the reflectance level at higher THz scale. We demonstrate these statements in the numerical results section for various problem parameters and angle of incidence

Scattering from the flat strip geometries in the layered medium by using the sinc based method of moments

Progress in Electromagnetics Research Symposium (PIERS 2008) -- JUL 02-06, 2008 -- Cambridge, MAWOS: 000259299300143In this study, we solved the electromagnetic scattering from the strip in the layered medium. The sinc type basis functions are used with their mathematical properties and GPOF technique provides us fast computation of the Green's functions in the layered medium. Therefore we obtain an algebraic matrix equation without using integration instead we used the approximated analytical forms with a specified error criteria like the few digits accuracy in the ordinary MoM.Schlumberger Doll Res, MIT Ctr Electromagnet Theory & Applicat, Res Lab Elect, Zhejiang Univ, Electromagnet Acad, Electromagnet Aca

Electromagnetic scattering from layered strip geometries: the method of moments study with the sinc basis

WOS: 000291757200007Electromagnetic scattering from strips of layers is analyzed using the method of moments (MoM) for both polarizations in spatial domain with the sinc-type orthogonal sets as basis and testing functions. We exploited the sine function's properties of exponential convergence, the orthogonality, easy convolution and better handling of singular kernels in MoM procedure resulting in fast performance and reasonable accuracy even in ordinary MoM treatment. We transferred the integral of the Hankel function multiplied by sinc functions to Hankel function introducing a slight error with large band width. We proved that this relative error during the generation of the main matrix elements is smaller than that of the free space error, i.e., 1%-0.5% for considerably large matrix sizes. Our approach is readily applicable to a singular kernel problem due to properties of the sinc functions in particular 2D geometry. The procedure undertaken here is proven to be very efficient as regard to similar treatments in the literature developed mainly for regular kernels. Various numerical results are calculated such as the surface induced current and normalized far field radiation pattern. We compared them with the results available in the literature

Radiation performance of metamaterial cylindrical reflector antenna having a conic section profile illuminated by An E-polarized complex source line beam

15th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) -- AUG 26-28, 2014 -- Dnipropetrovsk, UKRAINEWOS: 000364989500023Parabolic conic section profile, cylindrical metamaterial reflector antenna radiation characteristic is analyzed by using the Method of Analytical Regularization (MAR) techniques. E polarized complex source point is located at the focal point is used to illuminate the antenna. Far field radiation patterns are obtained for metamaterial and dielectric cases.IEEE AP MTT ED GRS NPS AES EMB E Ukraine Joint Chapter, O Honchar Dnipropetrovsk Natl Univ, Natl Acad Sci Ukraine, Inst Radiophys & Elect, Inst Elect & Elect Engineers, IEEE Aerosp & Elect Syst Soc, IEEE Geoscience & Remote Sensing Soc, Off Naval Res Global, TICRA Fd

ANALYSIS OF AN ARBITRARY CONIC SECTION PROFILE AND THIN DIELECTRIC CYLINDRICAL REFLECTOR ILLUMINATED BY AN E-POLARIZED COMPLEX SOURCE POINT BEAM

14th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) -- AUG 28-30, 2012 -- Kharkiv Natl Acad Municipal Econ, Kharkiv, UKRAINEWOS: 000312848800061We simulated arbitrary conic section profile and thin layer dielectric reflector using the Method of Analytical Regularization (MAR) techniques. The reflector is assumed to be illuminated by a complex source point type feed antenna in E-polarization mode. We obtained excellent accuracy and convergence of our simulation.IEEE, IEEE APS, MTT-S, Electron Devices Soc (EDS), GRS, NPS, AES, EMB, IEEE E Ukraine Joint Chapter, Natl Acad Sci Ukraine Radio-Phys & Microwave Elect,, Sci Council, Natl Acad Sci Ukraine, Inst Radiophys & Elect, IEEE SP & AE Soc Kiev Joint Chapter, IEEE Photon Soc Ukraine Chapter, IEEE IRE-Kharkiv Student Branch, URSI, Ukrainian NC, Commiss B, Opt Soc Amer (OSA), Off Naval Res Global, US Army Forward Element Command-Atlantic Res Div, TICRA Fdn, European Sci Fd

Analysis of a thin, penetrable, and non-uniformly loaded cylindrical reflector illuminated by a complex line source

WOS: 000418718700007A thin, penetrable, and cylindrical reflector is illuminated by the incident field of a complex source point. The scattered field inside the reflector is not considered and its effect is modelled through a thin layer generalised boundary condition (GBC). The authors formulate the structure as an electromagnetic boundary value problem and two resultant coupled singular integral equation system of equations are solved by using regularisation techniques. The GBC provides us to simulate the thin layer better than the resistive model which is applicable only for very thin sheets. Hence, the more reliable data can be obtained for high-contrast and low-loss dielectric material. The scattering and absorption characteristics of the front-fed and offset reflectors are obtained depending on system parameters. Also, the effects of the edge loading are examined for both E- and H-polarisations. The convergence and the accuracy of the formulation are verified in reasonable computational running time

Analysis Of Thin Dielectric Cylindrical Reflector Having An Arbitrary Conic Section Profile Illuminated By Complex Line Source: H-Polarization Case

15th International Conference on Mathematical Methods in Electromagnetic Theory (MMET) -- AUG 26-28, 2014 -- Dnipropetrovsk, UKRAINEWOS: 000364989500022Arbitrary conic section profile and thin dielectric reflector is analyzed by using the Method of Analytical Regularization (MAR) technique based on Riemann-Hilbert problem and Fourier inversion procedures. The reflector surface is assumed to be illuminated by an H-polarized complex line source type feed antenna. The convergence of the solution is verified and some changes in the radiation patterns are obtained especially for rather thicker cases.IEEE AP MTT ED GRS NPS AES EMB E Ukraine Joint Chapter, O Honchar Dnipropetrovsk Natl Univ, Natl Acad Sci Ukraine, Inst Radiophys & Elect, Inst Elect & Elect Engineers, IEEE Aerosp & Elect Syst Soc, IEEE Geoscience & Remote Sensing Soc, Off Naval Res Global, TICRA Fd