Practical antenna array designs generally require that the elements are separated by electrically short distances. The resultant mutual coupling often adversely affects the achievable performance. Various methods are available to quantify the effects of mutual coupling in arrays and improve performance through mutual coupling compensation. Mutual coupling is often described by a coupling matrix that relates the coupled and uncoupled quantities. Unfortunately, the accuracy with which the coupling matrix can be calculated is highly dependent on both the method selected and the frequency. This is a significant limitation for wideband analysis where the coupling matrix needs to be calculated accurately at all frequencies of interest. This paper introduces a novel method for the precise calculation of the coupling matrix at any frequency of interest. It is an extension of the induced EMF method to multiple array elements. The method has the important practical advantage of being independent of the numerical technique used in the analysis. Since the coupling matrix is calculated by exciting the elements in the transmission mode, the method resembles well-known network analysis. However, as outlined in the paper, there are subtle differences between the two approaches, which lead to more accurate results with the new proposed method. It is also demonstrated that antennas with arbitrary geometries and illuminations are handled accurately by the method.

High-order modes of spoof surface plasmon polaritons (SPPs) on the periodically corrugated metal surfaces are investigated theoretically with the modal expansion method. An analytical expression for the condition of existence of high-order modes is presented. The properties of high-order modes such as dispersion and field pattern are analyzed detailedly, from which it seems that the propagation of spoof SPPs along the corrugated metal surface is mainly based on the coupling between the open groove cavities.

The dispersion equation for free electromagnetic waves guided by an anisotropically conducting open tape helix is derived from the exact solution of a homogenous boundary value problem for Maxwell's equations without invoking any apriori assumption about the tape-current distribution. A numerical solution of the dispersion equation for a set of typical parameter values reveals that the tape-helix dispersion curve is virtually indistinguishable from the corresponding dominant-mode sheath helix dispersion curve except within the tape-helix forbidden regions.

This paper presents a theoretical model for the propagation of a hollow Gaussian electromagnetic beam [HGB], propagating in a plasma with dominant relativistic-ponderomotive nonlinearity. A paraxial like approach has been invoked to understand the nature of propagation; in this approach all the relevant parameters correspond to a narrow range around the irradiance maximum of the HGB. The critical curves for the propagation of various order HGBs have been discussed, and the dependence of the beam width parameter on distance of propagation has been evaluated for three typical cases of steady divergence, oscillatory divergence and self focusing of the HGB.

The optical properties of birefringent Bragg fiber with a fiber core of 2-dimension (2D) elliptical-hole photonic crystal structure has been study. Elliptical air holes are introduced into the fiber core to form a normal 2D photonic crystal structure with a hole pitch (center-to-center distance between the air holes) much smaller than the operation wavelength of the Bragg fiber. The elliptical-hole photonic crystal structure acts as an anisotropic medium with different effective indices for transmission light of different polarization, which inevitably results in high birefringence (up to the order of magnitude of 0.01) of the Bragg fiber. The proposed Bragg fiber possesses different band-gaps for differently polarized mode. Besides the periodic alternating layers of high/low refractive indices, the bandwidth of the band-gap is also dependent on the effective index of the fiber core, which can be controlled by the area of the elliptical air holes.

Focal region fields of a perfect electromagnetic conductor (PEMC) paraboloidal reflector placed in homogenous and reciprocal chiral medium are analyzed under the effect of high chirality parameter. The chiral medium supports both negative phase velocity (NPV) and positive phase velocity (PPV) modes simultaneously under strong electromagnetic coupling. The geometrical optics (GO) fields have singularities at the focal region. Therefore, to avoid these singularities Maslov's method is used for the focal region fields. The results obtained using this method are solved numerically, and line plots for the reflected field of the paraboloidal PEMC reflector are obtained for different values of admittance of the PEMC paraboloidal reflector and chirality parameter of the medium.

The response of a two-layer structure of orthogonal coupled microstrip transmission lines illuminated by an external electromagnetic field has been studied. A simple model for the crosstalk region using lumped capacitance and inductance elements is used. The effect of the external EM field on the microstrip lines field in order to reach transmission line equations along the lines. The model is finally validated using the full wave analysis simulator, HFSS. Voltage and current along the lines obtained by the present method are in good agreement with the results of the full wave analysis (HFSS). The proposed model has been used for voltage and current in terminal ports up to 10 GHz. This method can be developed simply for multilayer structures.

In this paper, a new design of a compact narrowband bandpass filter is proposed. This new narrowband bandpass filter is designed using an octagonal form of dual-mode closed-loop microstrip ring resonator based on a meander structure in order to achieve compactness. The designed filter has a 3 dB fractional bandwidth (FBW) of 5% at 2.3 GHz. The filter has been fabricated on Taconic CER-10 substrate having 0.64 mm thickness and a relative dielectric constant of 10. Experimental results show good agreement with simulated values. Apart from WiMax, this new model of filter is also useful for WLAN and mobile communication applications, since it is compact in size, low loss, and low cost with good performance of elliptic response with sharp rejection and adequate fractional bandwidth.

This paper obtains the topological 1-soliton solution of the nonlinear Schrodinger's equation in 1+2 dimensions, with power law nonlinearity and time-dependent coefficients. The solitary wave ansatz is used to obtain the solution. It will also be proved that the power law nonlinearity must reduce to Kerr law nonlinearity for the topological solitons to exist.

Maslov's method is used to derive the expressions for high frequency fields around the focal region of a paraboloidal reflector coated with isotropic and homogeneous chiral medium. The field expressions thus calculated are solved numerically, and the results are presented in the paper. Moreover, the dependency of the electric field on the thickness of the coated chiral medium and its properties is also studied. The results of this study are presented in the paper, and the conclusions are drawn accordingly.

Abstract：A hybrid high-frequency solution is proposed to analyze the bistatic electromagnetic scattering of the ship target on very large two-dimensional randomly rough sea surface in this paper. The comprehensive geometrical model of the ship and sea surface is designed by CAD tools and the sea power spectrum, and its electromagnetic scattering characteristic is evaluated with the method of equivalent currents (MEC). Since the electromagnetic interaction between the ship hull and the sea surface in the vicinity of the broadside is similar to the scattering mechanism of the dihedral reflector, the iterative physical optics method (IPO) is utilized to study the electromagnetic coupling effects. The shadowing correction based on the Z-Buffer technology is introduced to eliminate the effects of the irrelevant scattering resources. At last, the validity of the hybrid method is confirmed by the SAR image of the ship on the very large two-dimensional sea surface, and the numerical results are presented to analyze the composite scattering characteristics of the ship on the sea surface.

In this paper, the electromagnetic field of a horizontal electric dipole buried in a four-layered region is treated in detail. The region of interest consists of a perfect conductor, coated with the two-layered dielectrics under the air. Because of existing multi-reflections, the final representations of the six field components are much more complex. It is noted that the trapped surface wave and the lateral wave along the boundary between the air and the upper dielectric layer and those along the boundary between the two dielectric layers are included. Analysis and computations have some practical applications in microstrip antenna with super substrate.

A novel compact ultra-wideband (UWB) wide slot antenna with via holes is presented for UWB applications. The antenna is composed of a trapezoidal slot on the ground plane, a rectangular patch in the center of the slot and three via holes connecting the rectangular patch and the microstrip feed-line. The antenna is successfully designed, implemented, and measured. The measured results show that the proposed antenna with compact size of 27.0 mm×29.0 mm×1.0 mm achieves good performance, such as an impedance matching bandwidth of 111.7% (|S₁₁|≤-10 dB), constant gain and stable radiation patterns over its whole frequency range.

This paper presents a three-dimensional analytical expressions for studying the static magnetic field produced by Magnetic Resonance Imaging structures. This medical imaging technique uses a very high and uniform magnetic field produced by ring permanent magnets with rotating polarizations. However, the manufacturing of such ring permanent magnets is difficult to realize. Consequently, such ring permanent magnets are replaced by assemblies of tile permanent magnets uniformly magnetized. Unfortunately, the magnetic field produced by these tile permanent magnets uniformly magnetized is both less important and less uniform than the one produced by an idealized ring permanent magnet. We propose in this paper to study the influence of the number of tile permanent magnets used on the magnetic field properties.

In concrete industry, there is a need for water-to-cement ratio (w/c) estimation of cement-based materials since the w/c ratio of cement mixtures is typically given at the batch plant, and this ratio, sometimes, is deliberately changed to have a more workable cement mixture. To meet the requirements of accurate w/c ratio determination of cement-based materials, in this research paper, we propose an artificial neural network approach for w/c ratio estimation of these materials using free-space non-contact reflection and transmission measurements of mortar specimens with w/c ratios of 0.40, 0.45, 0.50, 0.55 and 0.60. We have tested the network and observed less than 5 percent difference between the estimated and known values of w/c = 0.50.

This paper presents a millimeter-wave ultra-wideband four-way switch filter module integrating six building blocks including four band-pass filters and two switches. The switch filter module works at whole Ka-band (26-40 GHz) and consists of four wideband band-pass filters and two monolithic microwave integrated circuit (MMIC) single pole four throw (SP4T) switches. The four wideband band-pass filters are realized by a novel three-line microstrip structure band-pass filter. Compared with the traditional three-line filter, the proposed three-line filter not only retains virtues of traditional three-line filter, but also resolves drawbacks of it which include discontinuities between adjacent sections, many parameters of design, and no effective matching circuits at input/output ports. The proposed three-line filter is validated by electromagnetic simulation. The developed switch filter module is fabricated using hybrid integrated technology, which has a size of 64 mm×44 mm×7.5 mm. The fabricated switch filter module exhibits good performances: for four different states, the measured insertion loss and return loss are all better than 8.5 dB and 10 dB in each pass-band, respectively.

The electromagnetic interface between the antenna and the human head is reduced with ferrite materials and metamaterials. The reduction of Specific Absorption Rate (SAR) with materials and metamaterials is performed by the finite-difference time-domain method with Lossy-Drude model by CST Microwave Studio. The metamaterials can be achieved by arranging split ring resonators (SRRs) periodically. The SAR value has been observed by varying the distances between head model to phone model, different widths, different thicknesses, and different heights of materials and metamaterial design. Materials have achieved 47.68% reduction of the initial SAR value while metamaterials achieved a reduction of 42.12%. These results can endow with supportive information in designing the wireless communications equipments for safety compliance.

This work focuses on microstrip patch antennas for the 77 GHz millimeter band. For some combinations of the parameters microstrip width, free wavelength and substrate permittivity, impedance matching via inset fed is found to be non applicable. The current distribution of the desired TM₁₀ mode is partially disturbed. Gap coupled parasitic microstrips are analyzed in order to match the feeding impedance to the feeding microstrip while improving the bandwidth in these particular cases.

An exact analytic solution is presented to the problem of scattering of a plane wave from a perfect electromagnetic conducting (PEMC) elliptic cylinder, using the method of separation of variables. The formulation is carried out by expanding the incident as well as the scattered electromagnetic fields in terms of appropriate angular and radial Mathieu functions and a set of expansion coefficients. The incident field expansion coefficients are known, but the scattered field expansion coefficients are unknown. Imposing the boundary conditions at the surface of the elliptic cylinder leads to the determination of the unknown expansion coefficients in closed form. Results are presented as normalized scattering widths for elliptic cylinders of different sizes and PEMC admittances, to show the effects of these on scattering.

In this article, a novel microstrip-line fed monopole dual band-notched antenna with tapered slot for UWB applications is presented. The tapered slot, making the antenna have a scissors-like shape, is taken into account to enhance the wideband characteristics. In addition, the dual notched bands, from 3.3 to 3.7 GHz and from 5.15 to 5.85 GHz, are achieved by inserting slots on the ground plane and adding circle arc stubs on the radiating patch. Details of the antenna design are described, a theoretical and experimental investigation of the antenna is given as well.