This paper establishes the extension of the method of auxiliary sources EMAS for the purpose of modeling the electromagnetic scattering response by jacket cylindrical structures constituted by a finite number of dielectric eccentric cylindrical inclusions embedded in a host dielectric one. Appropriate boundary conditions mixed with judicious decomposed domains leads to the prediction of the backscattering cross section. The algorithm also integrates the global electromagnetic coupling between the inclusions. The EMAS is validated by varying the inner cylinders repartitions and fine-tuning the electric permittivity according to different geometries. The EMAS level of accuracy compared with the indirect matching mode method IMM reveals a good agreement between the numerical computation results.

A wideband rod-dipole antenna with a modified feed for DTV signal reception in the 470-862-MHz UHF band is presented. The antenna consists of two retractable rod-dipole arms, which are connected to the opposite top corners of the modified feed. The feed is in the shape of a rectangle with dimensions 20 mm × 40 mm and divided into two portions by a U slit. The antenna can generate nearby resonant modes to attain a wide operating band, exceeding 60% bandwidth with VSWR below 3, much larger than that of the conventional center-fed dipole antenna. In addition, with the two dipole arms designed at the production stage to be able to swivel around, the antenna radiation and polarization thereof can easily be adjusted for better DTV signal reception without moving the whole antenna structure.

In this work, ideally hard struts with different cross sections are analyzed. Firstly, the characterization of the invisibility of a given object in terms of an equivalent blockage width is discussed. Then, the effect of the incidence angle on struts for reducing electromagnetic blockage using the same ideally hard cylinders is analyzed. It is shown that the variation of incidence angle in azimuth is very sensitive in terms of blockage for both polarizations. Finally, design charts for ideally hard struts which reduce blockage simultaneously for TE and TM cases are presented. This can be used to define some performance goals for final realized struts.

The novel characteristics of power propagation of guided modes in the chiral nihility fiber have been investigated theoretically. The formulas of electromagnetic fields in the core and cladding for guided modes are presented in detail. The dispersion equations, energy flux and power of guided modes are derived. The numerical results are given and discussed. Some exotic features of power propagation have been found in the chiral nihility fiber.

This paper provides a reliable dielectric measurement theory of the open resonator for non-planar objects such as convex-concave objects. It is the first time that the complete analytical formulas of the complex permittivity are presented by means of the second-order theory of the open resonator and field matching method. Furthermore, a measurement system is designed and built at Ka band, and the consistency of the results between planar and non-planar samples verifies the accuracy of the new theory. Finally, the experimental error analysis is investigated.

In this paper, rainfall effect on the VHF radio-wave propagation in a tropical forest is further studied in details. Theoretical study and experimental investigations are performed with the help of a four-layered model for forested environment. It is found that the lateral wave traveling along the air-canopy interface, the direct waves, and the ground reflected waves are the main modes for VHF radio-wave propagation in forest. The rainfall can affect these propagating waves to different extents. Especially, due to the increase in the dielectric permittivity of the wet canopy layer by rain water, the time of arrival of the direct wave traveling through the canopy layer can be delayed significantly. Finally, the dielectric permittivity for the wet canopy layer under different rain events is evaluated empirically.

We propose a general method to determine the material parameters for arbitrary shapes of cloak based on the Poisson's equation to map the coordinate transformation. As a result, we can obtain the diverse deformation material properties and then the field distribution. This method, compared with the previous technique presented in literature, can determine the countless transformation forms, so it may provide the opportunity to choose the optimization transformation and the material parameter map which is easily to be fabricated using the metamaterial technology.

A robust semi-deterministic facet model for the computation of the radar scattering cross section from the ocean-like surface is presented. As a facet-based theory, it is a more comprehensive model which can reflect the specular and diffuse configurations, as well as the mono- and bistatic features. Significant computational efficiency and good agreement with experimental data are observed, which makes the proposed facet model well suitable for fast estimation on EM scattering and synthetic aperture radar(SAR) imagery simulation of marine scene.

An analytical model of an effective permittivity of a composite taking into account statistically distributed orientations of inclusions in the form of prolate spheroids will be presented. In particular, this paper considers the normal Gaussian distribution for either zenith angle, or azimuth angle, or for both angles describing the orientation of inclusions. The model is an extension of the Maxwell Garnett (MG) mixing rule for multiphase mixtures. The resulting complex permittivity is a tensor in the general case. The formulation presented shows that the parameters of the distribution law for orientation of inclusions affect the frequency characteristics of the composites, and that it is possible to engineer the desirable frequency characteristics, if the distribution law is controlled.

In this paper, three approaches for the synthesis of the optimal compromise between sum and difference patterns for sub-arrayed linear and planar arrays are presented. The synthesis problem is formulated as the definition of the sub-array configuration and the corresponding sub-array weights to minimize the maximum level of the sidelobes of the compromise difference pattern. In the first approach, the definition of the unknowns is carried out simultaneously according to a global optimization schema. Differently, the other two approaches are based on a hybrid optimization procedures, exploiting the convexity of the problem with respect to the sub-array weights. In the numerical validation, representative results are shown to assess the effectiveness of the proposed approaches. Comparisons with previously published results are reported and discussed, as well.

A new beampattern synthesis formulation is proposed to compute the minimum number of array sensors required. In order to satisfy all the prescribed specifications of the beampattern, the proposed method imposes linear matrix inequality (LMI) constraints on the beampattern as developed by Davidson et al., which remove the need to discretize the beampattern region. As the proposed formulation is quasi-convex, an iterative procedure is used to decompose it into a systematic sequence of convex feasibility problems, in order to find the minimum number of sensors. The proposed method guarantees convergence if the globally optimal solution lies in the search interval, which is easily ensured at the start of the search.

A wideband unidirectional antenna composed of a magneto-electric dipole with Γ-shaped feed is designed. Simulated and measured results are presented. It achieves an impedance bandwidth of 84% for VSWR ≤ 2 ranging from 2.05GHz to 5.05GHz, stable peak gain of around 5 dBi, unidirectional radiation patterns and low cross polarization over the whole operating band. It is sufficient for accommodating recent wireless communication services such as 3G, WiFi, WiMax, Bluetooth, WLAN and Zigbee, etc.

This paper presents an Extended Exact Transfer Function (EETF) algorithm for Bistatic Synthetic Aperture Radar (BiSAR) imaging of a Translational Invariant (TI) case. This algorithm adopts directly the 2D transfer function of monostatic SAR (MoSAR), instead of deriving a new one, by converting the BiSAR into an equivalent MoSAR. A new azimuth phase compensation function is constructed through exploiting this equivalency. Geometry distortion correction for BiSAR imaging result is considered in the proposed algorithm. In addition, the applying condition of the algorithm is also discussed. One desirable property of the proposed algorithm is that the computing flow and efficiency are the same as ETF algorithm for MoSAR. The effectiveness is validated by point target simulations with Tandem and forward-looking configuration.

Use of water with different molecular mobilities could affect drug dissolution of a dosage form and such profile of water might be modifiable using microwave. This study investigated the effects of microwave on water and its influences on dissolution of free drugs and drugs in calcium-crosslinked alginate beads using sulphanilamide and sulphamerazine as hydrophilic and hydrophobic model drugs respectively. The water was treated by microwave at 300 W or without pre-treatment. The drug dissolution, pH and molecule mobility profiles of untreated and microwave-treated water were examined. Microwave-treated water had higher pH and water molecule mobility. The latter was characterized by higher conductivity, lower molecular interaction and crystallinity profiles. The dissolution of hydrophilic and hydrophobic free or encapsulated drugs was enhanced using microwave-treated water due to its higher molecular mobility. The untreated water of the same pH as microwave-treated water did not enhance drug dissolution. The drug dissolution from beads was increased by higher water uptake leading to matrix erosion and pore formation using microwave-treated water and was not promoted by the formation of non-crosslinked hydrated alginic acid matrix in untreated water of lower pH. Microwave treatment of water increased water molecule mobility and can promote drug dissolution.

In this paper, we present a new electromagnetic modelling analysis based on the Analytical Spatial Method of Moments (AS-MoM) using roof-top basis functions and prove advantages of integrals' resolution in conjunction with technique that permit to reduce the number of unknowns in the MoM matrix and to minimize time and memory consumption. This technique takes into account the existence of TEM zones inside the structure and far from discontinuities. There, we represent the current under an exponential form to analyze wave's propagation inside the structure. The advantages of this contribution will be illustrated by numerical results.

This paper discusses the design and development of a FPGA-based chirp generator for high resolution Unmanned Aerial Vehicle (UAV) Synthetic Aperture Radar. The desired bandwidth of the chirp signal is 100 MHz (combination of I and Q channels) with a chirp rate of 5 MHz/μs. Two algorithms based on the Memory-based architecture and the Direct Digital Synthesizer (DDS) architecture are presented. The measurement results indicate that the DDS chirp generator is a preferred choice for high-resolution SAR application.

Biological effects due to whole-body radio-frequency exposure may be induced by core temperature elevation. According to the international safety guidelines/standards for human protection, the whole-body averaged specific absorption rate (WBA-SAR) is used as a metric. In order to understand the relationship between WBA-SAR and core temperature elevation, a theoretical solution or a closed formula for estimating core temperature elevation is essential. In the present study, we derived a formula for simply estimating core temperature elevation in humans and animals due to whole-body radio-frequency exposure. The core temperature elevation estimated with the formula is found to be in reasonable agreement with the computational results of finite-difference time-domain computation incorporated in anatomically-based models. Based on the formula, the WBA-SAR is found to be a good metric for estimating core temperature elevation. The main factors influencing the core temperature elevation are the perspiration rate and the body surface area-to-weight ratio.

A study of electromagnetic wave propagation in dense plasmas when the wave frequency is below the cut-off frequency is presented. A three-layer symmetric structure consisting of dense plasma nested between two boundary layers is studied analytically and numerically. The permittivity of the dense plasma is negative, while the permittivity of each boundary layer is greater than 1. It is shown that total transmission of an electromagnetic wave can be achieved if an adequate incidence angle, dielectric permittivity of the boundary layers and corresponding boundary layer widths are chosen. It is found that plasma transparency is due to resonance between the evanescent waves in the dense plasma region and the standing waves in the boundary layers. Resonance conditions are derived analytically and the relationship between the corresponding parameters of the problem are studied numerically.

In this paper, electromagnetic scattering of a plane wave by large inhomogeneous arbitrarily shaped bi-anisotropic objects is solved by Adaptive Integral Method (AIM). Based on Maxwell equations and constitutive relationship for general bi-anisotropic media and using Volume Integral Equations (VIE), the electromagnetic fields are derived as functions of equivalent volume sources. Then the integral equations are discretized using Method of Moments (MoM). Because of the dense matrix property, MoM cannot be used to solve electromagnetic scattering by large objects. Therefore, AIM is adopted to reduce the memory requirement and speed up the solution process. Comparison between AIM and MoM with respect to CPU time and memory requirement is done to show the efficiency of AIM in solving electromagnetic scattering by large objects. Numerical results are obtained for some canonical cases and compared with Mie theory, in which excellent agreement is observed. some new numerical results are also presented for the more general bi-anisotropic material media.

Ultra Wideband (UWB) radar is a promising emerging technology for breast cancer detection based on the dielectric contrast between normal and tumour tissues at microwave frequencies. One of the most important considerations in developing a UWB imaging system is the configuration of the antenna array. Two specfic configurations are currently under investigation, planar and cylindrical. The planar configuration involves placing a conformal array of antennas on the naturally attened breast with the patient lying in the supine position. Conversely, the circular configuration involves the patient lying in the prone position, with the breast surrounded by a circular array of antennas. In order to effectively test the two antenna configurations, two 2D Finite-Difference Time-Domain (FDTD) models of the breast are created, and are used to simulate backscattered signals generated when the breast is illuminated by UWB pulses. The backscattered signals recorded from each antenna configuration are passed through a UWB beamformer and images of the backscattered energy are created. The performance of each imaging approach is evaluated by both quantitative methods and visual inspection, for a number of test conditions. System performance as a function of number of antennas, variation in tissue properties, and tumour location are examined.