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An efficient approach to analyze the electromagnetic (EM) scattering from coated objects above a three-dimensional (3-D) dielectric random rough surface is proposed in this paper. The electric and magnetic current densities on the sea surface are analytically realized using the semi-deterministic facet scattering model (SDFSM). Considering Fresnel reflection coefficient, a scheme combining the shooting and bouncing rays (SBR) and the physical theory of diffraction (PTD) is developed to calculate the scattering of the coated objects. Simulation results obtained with the combined method are verified by comparison with exact simulations using the multilevel fast multiple method (MLFMM). Scattering of large coated objects over sea surface composite model are too large and complex to be calculated using exact methods. With the asymptotic approach in this paper, the scattering performance can be analyzed with rather moderate computational efforts. Numerical results of composite scattering from an electric large three-dimensional model, e.g. an airplane target over a randomly rough surface with Pierson Moskowitz (PM) spectrum are presented and discussed. [ABSTRACT FROM AUTHOR]

Reflection and transmission properties of a planar interface of two non-integer dimensional (NID) half spaces are studied. It is assumed that dimensions of both half spaces normal to the interface are non-integer. Both half spaces are distinguished from each other by non integer dimensions rather than wavenumbers. A plane wave has been taken as source of excitation. It is observed that non integer dimensions are also the factors controlling the reflection and transmission properties of the interface. Special cases are also considered when one or neither of the two half-spaces are NID. [ABSTRACT FROM PUBLISHER]

In this paper, it is proposed that high reflection surfaces and polarization rotators can be designed using planar stratified metamaterials (MTMs). For this purpose, structures used in design are composed of strong chiral, dielectric, double negative, chiral nihility, and single negative MTM slabs. To investigate these multilayered structures, reflection and transmission coefficients are analytically computed using transfer matrix method. The expressions depend on frequency, angle of incidence, optical width of slab, and material parameters. The structures are tested for numerical values and then optimized results are presented. For each case, structure is composed of odd number of infinite length slabs. These structures can be used in filters, radomes, and polarization conversion devices. [ABSTRACT FROM AUTHOR]

In this paper, the response of a frequency selective surface (FSS) loaded with a nonlinear element is analyzed with the help of the harmonic balance method. The linear section of this configuration is composed of a freestanding FSS while its nonlinear section is a p-n diode biased with a DC voltage source. The method of moments is used to determine the impedance of the linear section at the fundamental frequency and its harmonics. The nonlinear section is modeled using the voltage-current relation of the diode. No simplifying assumption is made such that the analysis can be used to determine the steady state response of the nonlinearly loaded FSS for both large-signal and small-signal excitation. [ABSTRACT FROM AUTHOR]

Subwavelength cavity resonator microstrip antennas with conjugate left- and right-handed material bilayered substrates are proposed. Details of the antenna design are demonstrated based on the resonant dispersion relation. Due to the phase compensation effects, the total heights of the antennas still keep the subwavelength value, and even achieve further reduction. As is shown, confined bandwidth microstrip antennas with resonant sensitivity are obtained when the solutions to the resonant dispersion relation depend on the frequency. This result makes the considered structures promising candidates as subwavelength cavity resonator microstrip antenna sensors. [ABSTRACT FROM AUTHOR]

The method of moment (MoM) is a numerical procedure for solving the equation Lf = g, where L is a continuous linear operator, f is the unknown function to be determined and g is a known excitation. In essence, the procedure converts the linear equation into a matrix equation and determines the unknown function in the form of a set of samples of the function through matrix inversion. It is well known that the sampling theorem states that to completely represent a function, one requires a minimum of two samples per wavelength, when the basis function is the Sinc function. Thus, by choosing the Sinc function as the testing and basis function in MoM implementation, we should have the smallest possible size for the matrix. To test the above stated approach, we calculate the scattering coefficient from a 2-D rough surface with a Gaussian distribution. The standard point matching approach is also used so that comparisons can be made between the two results. By comparing these numerical calculations with the IEM model, it is found that to achieve the same degree of accuracy, the number of unknowns used in the point matching method is an order of magnitude more than when the Sinc function is used as the basis function. This reduction in matrix size is specially significant in a three dimensional surface scattering problem, because we shall be able to reduce the matrix size by two orders of magnitude [ABSTRACT FROM AUTHOR]

A novel design of ultra compact Planar Inverted F-Antenna (PIFA) is proposed for dual band resonant frequencies. The antenna is designed and fabricated on both foam and FR4 cheap substrates with dielectric constants εr = 1.07 and 4.7, respectively. Over 95% reduction in the antenna size is achieved from conventional λ0/4 rectangular PIFA resonating at same frequencies. This is done by implementing two oppositely shorting capacitive straps under the radiating surface. Dual band operation is achieved by inserting two parallel slots on the edges of the PIFA radiating surface forming an E-shape. In this case, the center wing resonates at the higher frequency while the two side wings resonate at the lower frequency. The antenna resonance frequencies on FR4 substrate are 1.07 GHz and 2.77 GHz with area's reduction ratios of 97% and 81% for lower and upper resonance frequencies, respectively. The antenna size on FR4 substrate is 13 × 11 × 8 mm3. The antenna directivity is 3.73 with radiation efficiency 97%. The radiation pattern has acceptable shape with low cross polarization in both resonances and at both E-plane and H-plane directions. [ABSTRACT FROM AUTHOR]

Presents an abstract of the study 'Wave Scattering by Periodic Surface at Low Grazing Angles: Two Grazing Mode,' by M.I. Charnotskii.

Presents an abstract of the study 'Wave Scattering by Periodic Surface at Low Grazing Angles: Single Grazing Mode,' by M.I. Charnotskii.