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.

In this paper, reduction of peak specific absorption rate (SAR) for handsets with monopole type antenna through R-cards is investigated. While the numerical analysis was performed using finite integration in time domain (FIT), real measurement has been made to validate the simulation results. Both the simulation and measurement results revealed that a minimum SAR Reduction Factor (SRF) of 60% was achieved. The good agreement between the simulation and measurement results has evidenced the effectiveness of the proposed approach for SAR reduction in human head for handset applications.

The wide-angle bicone antenna terminated by a spherical cap is investigated. The antenna radiation patterns have been observed for various values of where represents the phase constant and represents the conical length. It is seen that for large values of the radiation pattern is limited within an angular sector bounded by the cones of the antenna. Next the antenna is optimized for ultra-wideband (UWB) operation through the use of loading techniques. The transient wideband radiated and received responses of the antenna have been observed and the relationship between the wave shapes of the transient field and the input pulse have been determined.

Microwave breast tumour detection is a non-invasive technique that uses non ionizing radiation. Microwave imaging has the potential to achieve early detection of breast cancer due to the high specificity and the large difference in electrical properties of the malignant tissue when compared to normal breast tissue. This paper studies the feasibility of using UWB signals for breast imaging. Simulated results using Finite-Difference Time-Domain (FDTD) Method will be presented. A sensibility study of the variations in the breast relative dielectric permittivity and of the variations of the skin-surface contour is also provided. A working prototype for microwave imaging is developed using a conventional Vector Network Analyzer (VNA) with the time processing capability.

In the present investigation, diffraction from a slit in perfectly electromagnetic conducting (PEMC) plane has been studied. Both the E- and H-polarization are considered and the method of analysis is Kobayashi Potential (KP). The mathematical formulation involves dual integral equations (DIEs). These DIEs are solved by using the discontinuous properties of Weber-Schafheitlin's integral. The resulting expressions, finally, reduce to matrix equations. These are then used to compute the values of unknown expansion coefficients. Numerical results are presented for different parameters of interest especially the dependance of co-polarized and cross-polarized components on the admittance parameter.

This paper addresses the design of fractal antennas placed onto dielectric object in the UHF RFID band and introduces a tag antenna configuration of simple geometry having impedance tuning capability. Through the paper, the dimensions of the fractal antenna are optimized to improve the impedance matching with the chip impedance. The tag performance changes are studied when it is placed on different objects (e.g., cardboard boxes with various content), or when other objects are present in the vicinity of the tagged object. It has been shown that a tag antenna can be designed or tuned for optimum performance on a particular object. Using the finite element method the open circuit voltage and the polarization mismatch factor against the operating frequency are calculated. The input impedance, reflection coefficient, power transmission coefficient and the read range as a function of frequency are illustrated. The performance of the tag antenna in the presence of the dielectric box and different object materials inside the box is illustrated. The effect of the objects that are placed in the center of the dielectric box didn't have a significant effect on the performance of the tag antenna; there is a small shift in the resonance frequency but still within the operating frequency band. Both the power transmission coefficient and the read range change with the object material. The backscattering properties of the tag antenna have been studied. The differential radar cross-section of the tag antenna is calculated for different antenna loads.

In this paper, a novel source localization scheme is proposed based on the unitary ESPRIT algorithm with back ray tracing technique and the city electronic maps. Our scheme can be summarized into two steps. First, the unitary ESPRIT algorithm is employed to estimate the angles and delays of the arrival rays radiated from the source. Second, based on the obtained information we devise a back ray tracing technique to recover the signal propagation paths according to the Geometrical Theory of Reflections and the city electronic map. After these two steps the source position can be obtained by averaging all the estimated positions. In order to minimize estimated errors caused by the Unitary ESPRIT, a valid-range selection criterion for the judgment of the validity of the estimated position data is proposed. On the other hand, we introduce a path length weighting factor to reduce the estimated errors caused by the terrain data inaccuracy. This position method can locate both the line of sight (LOS) and non-line of sight (NLOS) sources efficiently and it also can locate multi-sources simultaneously. Six simulations are carried out in three terrain scenarios. The numerical results demonstrate that our model can be applied to estimate the positions for both 2D and 3D cases. The accuracy of our model for a cell of 80 m × 45 m can reach 10 m when SNR is greater than 10 dB.

A reconstruction algorithm for two- and three- dimen-sional microwave imaging is proposed. The present effort is focused on the reconstruction of conductivity (σ) and permittivity (ε_r) distri-butions aiming at a technique serving medical imaging, while perme-ability imaging can be easily incorporated to serve geophysical geophysical prospecting as well. This work constitutes the most recent one within the effort of extending our Modified Perturbation Method (MPM) from static to high and now microwave frequencies. MPM is an approximate method based on an exact Sensitivity or Jacobian matrix for an iterative update of an initial (σ, ε_r) guess until convergence. This method is proved almost immune of the problem inherent ill-posedness, but its robustness is actually gained by paying a penalty of compromised accuracy in the final achieved image. However, this image can be fine tuned by formulating and solving an exact inverse problem. Regarding the involved Jacobian matrix, this is evaluated through closed form expressions obtained through an Adjoint Network Theorem in conjuction with the electromagnetics reciprocity theorem. The field distributions required for its evaluation are readily available from the always required forward problem solutions on the assumed (σ, ε_r) distributions. Herein, the finite element method along with absorbing boundary conditions are employed for the forward problem electromagnetic simulation.