In this paper, a merged characteristic basis function method (MCBFM) is proposed to analyze the electromagnetic scattering characteristics from conducting targets. A merged characteristic basis function (M-CBF) is newly defined in the MCBFM. Considering the mutual interaction of surrounding blocks, the M-CBF is generated by merging the conventional secondary characteristic basis functions (SCBFs) and the high order characteristic basis functions (HO-CBFs) of each block in the conventional primary characteristic basis function (PCBF). Thus, the true current distribution of the targets is approached by using a single M-CBF reducing the number of CBFs when the incident plane waves (PWs) are certain. The numerical results of a PEC hexahedron demonstrate that the proposed MCBFM improves the accuracy without increasing the number of PWs and the CBFs compared to the improved primary CBFM (IP-CBFM). The results also demonstrate that the MCBFM is capable of effectively reducing the CPU time by 63.38% without losing any accuracy compared to the conventional characteristic basis function method (CBFM). Other results of a PEC cylinder demonstrate that when a considerable computational accuracy is required, the efficiency of the proposed MCBFM is the highest among these three methods.

In this letter, a new coplanar waveguide (CPW)-fed monopole antenna with equilateral-triangular shape is presented and experimentally investigated. The structure under study generates three different center frequencies corresponding to the lower, middle, and upper bands for Wireless Local Area Networks (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The proposed antenna is analyzed using the Computer Simulation Technology (CST) Software. To validate the simulation results, an experimental prototype of the proposed design is fabricated, tested and measured. The experimental results show a good agreement with the simulated ones.

In a previous work, improved full-wave analytical expressions have been derived for the Sommerfeld Integrals (SIs) describing electromagnetic radiation from a short vertical straight wire located in close proximity to a conductive soil. Such formulas ensure high accuracy of the result of the computation, as well as time savings with respect to conventional techniques used to evaluate the SIs, but unfortunately may be used only when both source and field points are located at the air-medium interface. The scope of this paper is to overcome the limitations implied by the previous approach, and provide series-form expressions for the generated field components that are valid for an arbitrarily stratified medium and for any position of the vertical wire antenna and observation point in the air space above it. The expressions follow from the analytical evaluation of the integral representation for the magnetic vector potential, performed through contour integration after substituting an equivalent pole set for each branch cut of the integrand. Validity, efficiency and accuracy of the developed formulas are illustrated through numerical examples.

In this paper, a technique to identify/synthesize an equivalent circuit of nonreciprocal lossy N-port device is presented. The technique joins the classical procedure discussed in the '60s to the polygon network recently proposed in the literature, which permits to draw an equivalent circuit for reciprocal lossless N-port device in a very simple way. The identication is applied to two microwave devices, a reciprocal lossy iris in WR90 waveguide and a 3-port nonreciprocal lossy circulator. The proposed equivalent circuit could give some information about the agreement of the manufactured device and its design, which usually is developed in the hypothesis of ideal lossless components.

The calculation method for electromagnetic field scattered by antenna placed inside nose dielectric radome is proposed. To obtain the radiation characteristics, we use the calculation method for field generated by radiation aperture given that an arbitrary system of scatterers (particularly, radome) exists in its vicinity. Also, the method for calculating radiation characteristics of antenna system with the same radomes is obtained. Considered numerical results tell us that influence of radome on radiation characteristics can be reduced to minimum for any radome type. Besides, the radome can reduce the radar visibility of antenna system outside of its operating frequency range.

A novel and compact triple-band Y-shaped monopole antenna with dual-polarization characteristics is proposed. The antenna is composed of a partial ground and a microstrip-fed radiating patch that consists of two unequal monopole arms and a circle monopole. The antenna is able to generate three separate impedance bandwidths of 230 MHz (2.30-2.53 GHz), 170 MHz (3.38-3.55 GHz), and 4170 MHz (4.35-8.52 GHz), which can cover both of the WLAN bands (2.4 and 5.8 GHz) and WiMAX band (3.5 GHz). By utilizing different lengths of monopoles, two circularly polarized bands at 2.4 GHz and 5.8 GHz are realized. Moreover, the antenna exhibits monopole-like radiation patterns and stable antenna gains across the operating bands. The effect of the antenna's key structural parameters on its performance was also analyzed.

This paper investigates the phase glint problem involved in interferometric synthetic aperture radar (InSAR) image processing, which refers to the multiple scatterer interference of a single pixel, and studies the distribution of interferometric phase in the case of double scatterer interference. It is found that the value range of the observed interferometric phase is related to several factors including the complex scattering coefficient ratio and interferometric phase difference between the elementary scatterers, and no matter what values of interferometric phases of elementary scatterers are taken, the dynamic range of interferometric phase of phase glintis always. This paper also briefly analyzes the impact of phase glint on classical InSAR image processing and man-made target height retrieval, and it is concluded that the phase glint will induce significant height estimating error. Simulation and real data results verify the conclusion.

Magnetic resonant wireless power transfer (WPT) is an emerging technology that may create new applications for wireless power charging. However, low efficiency resulting from the change of the transfer distance is a main obstructing factor for promoting this technology. In this paper, a method of fast tracking optimum efficiency is proposed. The input impedance value is obtained by measuring the input current. Then the transfer distance is estimated by the input impedance value. The optimum load resistor is obtained under a given transfer distance. In addition, the extended L-matching network is proposed in order to automatically adjust the load resistor. The key parameters of the matching network are also given. The optimum efficiency can be fast tracked by the proposed method as the transfer distance varies. The WPT system and the extended L-matching network are designed. Simulated and experimental results validating the proposed method are given.

A compact ultra-wideband planar monopole antenna with a notched band at WLAN frequencies is presented. The antenna is fed using a finite ground coplanar waveguide and has a structure consisting of stair-shaped radiator and ground plane. The notched band is implemented by cutting two symmetrical narrow slits from the ground plane. The antenna is fabricated on a substrate with a dielectric constant of 4.4 and has a compact size of 18×26×1.6 mm3. Experimental and simulation results of the fabricated antenna are found to be in good agreement. The antenna achieves an average gain of 3 dBi and efficiency of more than 80% over the operational band. Time domain analysis, which includes the group delay response and fidelity calculation, implies that minimal distortion is introduced by the proposed antenna which makes it suitable for portable pulsed UWB systems.

Due to the influence of aerodynamic forces, the wing will be subjected to vibration and deformation. This will result in a severe performance degradation of the wing conformal antenna. To solve this problem, a new gain-phase error compensation method based on the deformation fitting of wing conformal antenna is proposed. In this proposed method, the array deformed shape curve is fitted through the gain error of the array, thus the position of each element can be calculated. Finally, by using the position of the elements to calibrate the gain-phase error, the corrected directions of arrival (DOA) estimation angle is obtained. Simulation results show that the proposed method can well reproduce the shape of the array, and effectively compensate the position error caused by the vibration of the wing conformal antenna.

The proposed filter satisfies the Federal Communications Commission ultra-wideband (FCC-UWB) specifications, and also creates and controls sharp rejection notch-bands within the filter's passband in order to provide interference immunity from unwanted radio signals, such as wireless local area networks (WLAN) and worldwide interoperability for microwave access (WIMAX) that cohabit within the UWB spectrum. This filter is based on CRLH concept consisting of an asymmetric transmission line unit cell with a short circuited inductive stub to realize high performance in an operation band from 3.1 to 10.6 GHz with a very compact size of 16.4mm × 5.0 mm. The main advantage of the proposed filter is that four notch frequencies are tuned in the UWB frequency band. The notch frequencies of the filter can be changed by increasing the length of the coupling stub which is controlled by using switching matrix equipment (Mini Circuit) instead of PIN diodes. To validate the design theory, a microstrip UWB BPF with four notch bands centered at frequencies 6.18, 5.9, 5.7, and 5.5GHz is designed and fabricated.

This study investigates the generation and mitigation of common-mode noise (CMN) in a common structure which consists of differential traces with adjacent ground lines and a ground plane. For simplicity, a simple test structure similar to the common structure is proposed. The test structure is divided into three parts. One part is composed of differential traces with adjacent ground lines. The second is composed of differential traces with adjacent ground lines that are connected to a ground plane. The third comprises differential traces with an adjacent ground line and an adjacent ground plane. The generation and mitigation of CMN in these three parts are studied. Test structures with different designs are investigated to confirm the effectiveness of the CMN mitigation schemes. Based on these analyses, design guidelines for mitigating CMN are provided. The proposed design guidelines reduce the peak-to-peak CMN amplitude by 81% from that achieved using unsuitable design of test structure. In the frequency domain, the reduction of the magnitude of differential-to-common mode conversion (|S_cd21|) at the resonant peaks exceeded 40 dB in the frequency range 0 GHz~6 GHz. Finally, a favorable comparison between simulated and measured results verifies the favorable CMN mitigation performance of the proposed design guidelines.

Torque pulsations in Permanent Magnet Synchronous Machines are mainly created by interaction between the permanent magnets and stator teeth, harmonics in the stator current, steel saturation and partial magnet demagnetization. As a consequence of torque ripple, there are increased noise and vibrations. To overcome them, some methods for reducing pulsating torque include controlled-asymmetry. The strategy seeks for compensate or cancel out spatial harmonics of flux density in the air gap. This work proposes an analytical method based upon sub-domain model that allows techniques such as stator teeth pairing, slot opening shift, nonuniform teeth, tangential shift of magnets, different magnet widths, among others, to be utilized and quickly analyzed. Since asymmetries introduce several degrees of freedom, the design of Permanent Magnet Synchronous Machines can be accelerated by means of analytical-based tools. The proposed model is validated with Finite Element method.

Based on order one-loop effective Lagrangian derived from the 2-point photon vertex in quantum electrodynamics, we obtain a quantum modified Maxwell equations, and the classical expression of retarded potential is consequently modified by these equations. The results indicate that, due to the time-space non-locality of vacuum polarization, the vacuum polarization current is delayed relative to the field variation and induces a series of additional retarded potentials except for the classical part of retarded potential. Particularly, compared to the classical potential, these additional potentials are further retarded. Because the retard potential is the base of theory of electromagnetic radiation, the results of this work are of great value to the studies of quantum effect in ultra-intense electromagnetic radiation.

In this paper, a miniaturized Vivaldi antenna for C- to X-bands is proposed and fabricated. An H-Shaped Resonator (HSR) and transverse slot structures are employed in this design, which improve the gain through the entire band, especially at the higher frequency band. These simulated results show that the modified Vivaldi antenna has a maximum gain increment of 4 dBi and maximum gain of 9.9 dBi. Furthermore, the modified Vivaldi antenna has narrower half-power beam width (HPBW), higher front-to-back ratio (FBR) and better radiation characteristics. The proposed antenna is fabricated and measured to validate the design. The measured results are in good agreement with the simulated ones.

In the design of a conformal patch antenna array, a special care must be taken regarding the placement of elements and curvature bending. Presently, the authors try to explain the effect of these two factors on the key parameters such as return loss, mutual coupling, gain and directivity. Here, the analyses of parameters are done under the consideration of dielectric coated two-element antenna array model. This paper attempts to examine the characteristics of the dielectric coated conformal antenna array by varying its inter element spacing on the changing cylindrical geometry. The two-element conformal array is considered in E-plane and H-plane configurations, and its parameters are analyzed using full wave analysis and verified by HFSS tool. A comparative study shows that the E-plane configuration gives better result than H-plane configuration.

The electromagnetic (EM) waves influence substances involved in the propagation medium which leads to deviation or modification. Atomic stresses and strains caused by EM radiation make electromagnetic waves able to stir small particles by exertion of Lorentz force on them which is employed to deviate particles in this paper. The particles are considered as millimeter and micrometer-sized spheres with random electrical properties. Generalized Multi-Particle Mie theory (GMMT) is used to calculate scattering parameters such as Radar Cross Section for aggregates of arbitrarily oriented particles. The direction of motion caused by exerted Lorentz force on particles is accurately obtained in terms of Discrete Dipole Approximation (DDA). A bulk model based on Effective Medium Theory is designed to analyze the scattering parameters of particles, much smaller than incident wavelength. Application of this model is validated by several simulations. The profile of arbitrary incident wave and its amplitude and polarization effects on deviation are investigated, respectively. Numerical results are derived for various arbitrary orientations and different electromagnetic conditions.

This paper describes a multi-pass InSAR imaging approach for surface deformation studies. Such a technique extends concept of SAR tomography (TomoSAR) based on multi-pass InSAR data, in order to produce deformation map in elevation domain and velocity domain, respectively. Compared to conventional InSAR method, multi-pass InSAR imaging technique acquires multi-baseline information and allows reconstruction of multiple scattering sources in Tomo-Doppler plane (Elevation-Velocity plane). This technique offers a solution to layover issue over conventional InSAR method, but it suffers from double-scattering problem. This paper simulates a phenomenon where double-scattering impairs the imaging process and an improved solution method to separate single and double scatters from inferring pixels. In real circumstance, there are still other interferometric issues such as phase ambiguities of noise and phase discontinuity. Thus, a phase-unwrapping method associated with an improved ordered-statistical lter is included for interferometry processing. An experiment based on real SAR data is set up to demonstrate this technique.

The scattering of the electromagnetic waves by the spherical particles is discussed. Nanometer-sized dielectric spheres confined in a cluster are devoted to investigate the effect of the EM radiation on them. Incident wave is considered to be in visible light spectrum which facilitates multiple scattering calculation for nanoparticles. Radiation forces are discussed in terms of scattering pressure and Lorentz force, hence Discrete Dipole Approximation (DDA) and classical Mie theory is employed in radiation force computation and electromagnetic random multiple scattering analysis. Electric momentum of dipoles is defined in the term of A-1 term method. The radiation forces on particles are accurately calculated with computer codes. Extracted results can be applied to conscious deviation of spherical nanoparticles in clean rooms or similar mediums. The effect of the incident wave parameters and the orientation of spherical profile and particles in the cluster are predicted through various simulations.

In this paper, a general multilayer circular cavity with N slabs is analyzed analytically, obtaining characteristic equations for TE and TM modes to compute the complex resonant frequency efficiently using an algorithm based on Chebyshev's root finder. The accuracy of the solutions is compared with full-wave circuit method, and the computational speed to achieve the roots of the characteristic equations is also compared with Cauchy Integral Method, which is commonly used to obtain complex roots. Furthermore, the relationship between the amplitudes of the different regions is obtained, whereby the whole structure can be analyzed as a single one from now on.