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.

Two-Dimensional Direction of Arrival (2D-DOA) estimation is increasingly important in recent years. In this paper, a new method is proposed to estimate the 2D-DOAs of multiple spatial sources using a three-parallel uniform linear array assuming that some of the sensors happen to be out-of-order. Firstly, a Matrix Completion (MC) algorithm is applied to recover the observed incomplete data, and then an improved joint azimuth and elevation angle estimation algorithm using the recovered data is proposed to obtain the correct parameter estimation. Finally, computer simulation results show that the proposed algorithm has a great performance improvement compared to those based on incomplete data in terms of Signal-to-Noise Ratio (SNR) and the sample rate of sensors.

This article presents a microstrip fed patch antenna array, loaded with metamaterial superstrate. An unloaded antenna array resonates at IEEE 802.16a 5.8 GHz Wi-MAX band with gain of 4.3 dBi and bandwidth of 425 MHz whereas when the same array is loaded with a metamaterial superstrate, composed of the pair of Split Ring Resonators (SRR), there is simultaneous gain and bandwidth improvement to 8 dBi and 680 MHz, respectively, which corresponds to gain improvement by 86% and bandwidth enhancement of 60%. The fabrication of this proposed antenna array is done, and its simulated and measured results compared. Equivalent circuit model of this composite structure has been developed and analyzed. The electrical dimension of the patch is 0.23
λx0.3λ
.

This paper presents a compact size crossover device based on the cascade of branch-line sections. With the aim of reducing its size, some of the transmission lines of the structure have been replaced by its equivalent artificial transmission line (ATL). The obtained size reduction is above 30%, and the electrical performance of the proposed structure presents an isolation better than 20 dB in a FBW=34.5% and a crossover bandwidth better than 2 dB of FBW=51.5%. Also the good magnitude and phase balance performance must be highlighted.

A hybrid-polarity architecture, consisting of transmitting circular polarisation and receiving two orthogonal linear polarisation and also their relative phase, was used to calculate four Stokes parameters. Different parameters like Degree of Polarisation, Alpha angle, Entropy, Anisotropy, Radar vegetation Index and decompositions like Raney decomposition (m-δ), Freeman-2 and 3 component decompositions were derived from these hybrid data. Crop biophysical parameters viz. plant height, plant age and plant biomass of cotton crops grown under two different environments, i.e., rainfed and irrigated in Guajrat, India were studied with respect to derived polarimetric parameters. Right circular transmitted and horizontally (RH) and vertically (RV) received backscatter values show good relation with the plant height, age and biomass. RH backscatter -13 dB to -7 dB and RV backscatter from -13 to -10dB were observed for crop biophysical parameters. Volume component of all decomposition showed strong response to the increase in height, age and biomass of the plant. Radar Vegetation index (RVI) values have also shown significant increase from 0.6 to 0.7 with increasing age of the crop. The rate of growth was slow in the initial phase, but fast post mid-July for both early and late sown cases. The polarimetric parameters were found significantly correlated to the above plant biophysical parameters.

In this paper we compare current implementations of commonly used numerical techniques - the Finite-Difference Time-Domain (FDTD) method, the Finite-Integration Technique (FIT), and Time-Domain Integral Equations (TDIE) - to solve the canonical problem of a horizontal dipole antenna radiating over lossless and lossy half-spaces. These types of environment are important starting points for simulating many Ground Penetrating Radar (GPR applications which operate in the near-field of the antenna, where the interaction among the antenna, the ground, and targets is important. We analysed the simulated current at the centre of the dipole antenna, as well as the electric field at different distances from the centre of the antenna inside the half-space. We observed that the results from the simulations using the FDTD and FIT methods agreed well with each other in all of the environments. Comparisons of the electric field showed that the TDIE technique agreed with the FDTD and FIT methods when observation distances were towards the far-field of the antenna but degraded closer to the antenna. These results provide evidence necessary to develop a hybridisation of current implementations of the FDTD and TDIE methods to capitalise on the strengths of each technique.

A quarter-wavelength folded patch antenna is adopted as the passive wireless strain sensor for structural health monitoring (SHM) of bridges. It can be used for continuous surveillance and damage detection. According to theoretical formulations, strain simulation and experiments, it is found that a good linearity relationship can be achieved between normalized resonance frequency shift and the strain both in longitudinal and transverse directions. And the sensing sensitivity in longitudinal strain is better than that in transverse strain. Through conducting tensile experiments, we find that many factors can influence the strain sensitivity. To address this fundamental issue in antenna sensors for strain sensing, a new strain sensitivity experiment is proposed to take the influence of strain transfer ratio change under strain. The linear relationship of strain transfer ratio and deformation is obtained by sensitivity experiment. The corrected sensitivity in longitudinal and transverse strains is calculated based on the linearity. Furthermore, the Possion effect is taken into consideration to explain the opposite effects of experimental and simulated sensitivities in transverse strain.

In this paper, we design an optical filter by using one-dimensional (1D) ternary metallo-dielectric photonic crystal (PC). We use a dielectric defect layer between ternary asymmetric cells with this structure (ABC)^ND^M(ABC)^N and also increase the number of dielectric defect layers. Then, we plot transmission spectra in terms of wavelength and different angles of incidence in transverse electric (TE) and transverse magnetic (TM) polarizations. We show defect modes and photonic band gap (PBG) on the plane of wavelength and incident angles in both TE and TM polarizations. We also plot transmission in the lossless structure and compared loss and lossless structures. Furthermore, we compare dielectric defect layer with metallic defect layer in both TE and TM polarizations. Moreover, we plot symmetric structure (ABC)^ND^M(CBA)^N in TE and TM waves. The theoretical analysis shows that there is one defect mode which moves to the shorter wavelength by increasing angles of incidence in asymmetric structure. There are also two defect modes in symmetric structure, and by tuning angle of incidence this structure can be used as single channel filter in asymmetric structure and multichannel filter in symmetric structure.

A material sample of Camphour Sulphonic Acid doped Polyaniline (PANI-CSA) is contemplated towards its conceivable use as a microwave shield. Shielding towards electromagnetic interferences (EMI) is measured over various frequency bands by the waveguide method. Plane wave electromagnetic theory is used to generalize the overall reflection and transmission coefficients of the polymer. EMI shielding of the polymer, in the form of Shielding Efficiency (SE), is analyzed over the microwave frequency range from 2 to 18 GHz, demonstrating the potential value of the polymer as an electromagnetic interference (EMI) shield for commercial purposes. The shielding film is fabricated using standard procedure with CSA as the dopant and m-cresol as the solvent. The shielding effectiveness as high as 45 dB for the sample of PANI doped with CSA is observed.