In this paper, a fast and efficient method based on MOM is proposed for the analysis of antenna and array mounted on bodies of revolution. An attachment mode is introduced to ensure the continuity of current density at the junction region between wire antenna and cylindrical surface. A method based on suitable changes of coordinates and domains is presented to extract singular point of the self-impedance element calculation at junction region and accurate impedance can be obtained. Taking the antennas and array mounted on a finite solid conducting cylinder as an example, the impedance characteristics and radiation pattern are calculated. The good agreement between the results obtained by using the analysis method presented in this paper and those of CST and NEC software reveals the accuracy and high efficiency of this method.

This paper is addressed to a design of K-band dual mode radar used in traffic information collection. The radar can work in both Frequency Modulate Continual Wave (FMCW) mode and Continual Wave (CW) mode. As VCO is seldom used as the oscillator in CW radar for velocity measurement, this paper studied the effect of phase noise and detecting distance on velocity error in CW mode in VCO design. The analysis shows that the effect of phase noise on velocity error can be reduced by shortening the detecting distance. There's little difference in short-range velocity measurement between the dual mode radar with MMIC VCO and the CW radar with low phase noise oscillator.

Off-axis ellipsoid reflector based off-focus configuration for deastigmatism and circularization of an elliptical Gaussian beam is proposed. Mostly used off-axis ellipsoid reflector based conventional configuration is constructed by aligning the incident direction directed to one focus of the ellipsoid, which reflect the output beam to the another focus of the ellipsoid. However, such configuration is unavailable to deastigmatize and circularize an elliptical Gaussian beam. Therefore, the coupling efficiency between the reflected beam and an essentially circular beam is not well satisfied. In this case, an off-axis ellipsoid reflector based off-focus configuration is proposed to obtain better coupling efficiency. Different from the conventional configuration, in the proposed off-focus configuration, the incident beam direction is diverged from one focus of the ellipsoid. As a result, the coupling efficiency of no less than 99.9% (as compared with coupling efficiency of about 94.2% based on conventional configuration) can be obtained, which is verified with numerical calculations.

Electromagnetic scattering of two or more incident plane waves has been investigated for a perfect electromagnetic conductor (PEMC) circular cylinder, coated with a metamaterial havingneg ative index of refraction. The incident waves are considered for both the TM and TE cases in the analysis. The scattered fields are calculated by the application of appropriate boundary conditions at the interfaces between the different media. It is assumed that both the PEMC cylinder and the coatingla yer are infinite alongthe cylinder axis. The numerical results are compared with the published literature, and are found to be in good agreement.

Utilization of electromagnetic band-gap (EBG) structures is becoming attractive in the electromagnetic and antenna community. In this paper, the effects of a two-dimensional electromagnetic bandgap (EBG) Structures on the performance of microstrip patch antenna arrays are investigated using the Ansoft High Frequency Selective Simulator (HFSS^TM). A mushroom-like EBG structure is compared with 2-DEBG Structures. HFSS^TM is employed to determine the effects of different Structures on two element microstrip patch antennas array. Two element microstrip patch antenna array on a uniform substrate suffer from strong mutual coupling due to the pronounced surface waves. Therefore, diverse forms of 2-DEBG Structures like: little number of holes, large number of holes, defect mode and different number of mushroom-patches columns structure are discussed. The two element microstrip patch antennas array placed on a defect in the electromagnetic (EBG) substrate that localizes the energy under the antennas. The excitation frequency of the two element microstrip patch antennas array near the resonance frequency of the defect mode can be used to control the coupling between antennas that are placed in an array. The mutual coupling improved by using large number of mushroom-patches columns structure.

A no-load induction motor under static eccentricity is modeled using time stepping finite element (TSFE) method; current, torque, and speed signals of the motor are obtained by finite element method (FEM) and used for static eccentricity fault diagnosis and analysis. The frequency spectrum analysis of the stator current around fundamental frequency component is used to predict the static eccentricity. Noise, unbalanced magnetic pull (UMP) and arc occur during the starting of the faulty motor, therefore, performance of the motor over the period of starting up to the steady-state is investigated. It is shown that the rate of obtained signals from the constant permeability based analysis is very larger than that of the real case. It is indicated that in order to obtain accurate results the saturation must be taken into account in the analysis of the motor. Simulation results for a 3 hp, three-phase, 230 V, 36 stator slots induction motor with 28 rotor slots are given in this paper. Experimental results for the motor confirm the simulation results very well.

Electrostatic velocity shear Kelvin-Helmholtz instability has been studied for bi-Maxwellian plasma in the presence of perpendicular a.c. electric field by using the method of characteristic solution. The effects of a.c. electric field temperature variation, velocity shear scale length,electron ion temperature ratio and other parameters on growth rate have been discussed.

In this work, a generalized procedure is carried out for the design of a microwave amplifier. First of all, the Performance Data Sheets (PDS) resulted from the active device characterization are used as Feasible Design Target Space (FDTS). Employing the PDS, the compatible (Noise F, Input VSWR V_i, Gain G_T ) is determined over the predetermined bandwidth B between f_min and f_max operation frequencies with the source Z_S and load Z_L terminations as the design target. In the design stage, the Simplified Real Frequency Technique (SRFT) is utilized in the scattering-parameter formulation of the front- and back-end matching two-ports to provide the source and load terminations to the transistor, respectively. As an application example, a novel high technology transistor is chosen and the design targets are determined using the PDSs of the device and its frontand back-end matching two-ports are characterized by the scatteringparameters using the novel SRFT for each design target. Furthermore, the performances of the resulted amplifier circuits are analyzed and compared with the simulated results.

This paper presents a novel resistively loaded antenna design for microwave breast cancer detection. The antenna is planar and ultra-compact,and can be easily manufactured using PCB technology with embedded thin-film resistive layers. Through numerical simulations,the antenna demonstrates a return loss below -10 dB over a wide frequency range from 2 to 35 GHz. For pulse radiation in the ultra-wideband (UWB) range in a biological medium, the antenna shows an excellent fidelity above 0.95 and a relatively high radiation efficiency of 39.21% in comparison to resistively loaded antennas. In addition,a design rule guideline is presented for designing the antenna to radiate in a specific background medium and with a given lower operating frequency. Finally,a complete microstrip feed design is presented for the antenna operating in the UWB range.

An active-antenna array with 18 transmit elements and 18 receive elements is designed and fabricated. This T/R array can work at two different frequencies (19.5 GHz and 21.5 GHz) with multiple levels of isolation between the transmit and receive channels. A hybrid element-level vector finite element and adaptive multilevel fast multipole method (ELVFEM/AMLFMA) is applied to simulation the performance parameters of the array element and the full array fast. To obtained the maximum directivity of the array,the best distances of the T/R elements in the array are optimized by using the genetic algorithm (GE) combining with VFEM/AMLFMA. The design efficiency of the array is improved at a ratio of 30%. Finally the performance of the T/R array fabricated is measured in experiments and some good results are obtained.

Radar Cross Section is most of the time defined in far field. In that case, RCS is totally independent of the range between the radar and the target. However, in several kinds of military scenario, it can be more realistic to deal with the target nearfield scattering characteristics. Using a relation to define near-field RCS, this communication proposes simple and approximated analytical formulas to express monostatic near-field RCS of perfectly conducting flat targets observed in normal incidence.

In order to meet the approximate plane-wave irradiation condition, adequate large field or compact range system is needed for RCS measurement of large aircraft targets. However, an outside testing field site or a compact range system is very expensive, so some kinds of RCS extrapolation methods based on near-distance testing have been presented. In this overview, two categories of extrapolating technique are summed up, which are based on Huygens Equivalent Reradiating Source (HERS) and Inverse Synthetic Aperture Imaging (ISAI) respectively. Each method is fully elaborated. The comparison and analysis of these extrapolating techniques are discussed in detail.

This paper focuses on the radar cross section (RCS) reduction for the three-dimensional object with anisotropic impedance coating. In this work, a genetic algorithm is adopted to optimize the RCS of the anisotropic impedance object in desired angle range. The surface impedances are considered as the optimized parameters and the scattering of the object is computed by the PO method. The optimization process is demonstrated by considering the RCS reduction of two typical targets: the cone and the cone/cylinder composite structure. It is found that the optimization process can reduce the RCS of the targets remarkably and the anisotropic impedance coating has better RCS reduced effect than the isotropic impedance coating.

In this paper a novel rose leaf shape microstrip antenna with capacitively coupled rectangular fed is presented. Various shapes of capacitive coupled fed are compared and optimized by successive iterations of a computer-aided analysis. The Ansoft HFSS is employed for analysis at the frequency band of 4.3 GHz-8.3 GHz. The antenna is fabricated and measurement results show a very good agreement with the simulation results. The proposed antenna is able to achieve an impedance bandwidth about 69%. Effects of varying the parameters on the performance of the antenna have also been studied. The proposed antenna can be used in wireless ultra-wideband (UWB) communication.

A two-slot array antenna on a concentric sectoral cylindrical cavity excited by a coupling slot is investigated. The electromagnetic fields and Q factors for the first few modes of a concentric sectoral cylindrical cavity are presented. It shows that the appropriate mode for a slot array antenna on a concentric sectoral cylindrical cavity is the TM₁₁₀ mode. The correlations between each mode distribution and the magnetic field distributions inside the cavity are presented. The antenna design and the parametric study of a two-slot array antenna on a concentric sectoral cylindrical cavity for a single sector are illustrated. Simulated results are validated by measurements. The results provide useful information for the design of a switched-beam slot array antenna on the concentric sectoral cylindrical cavities.

In this paper, a general symmetry-based approach to the electrodynamics of a class of low-dimensional structures, carbon nanotubes, is proposed. The contribution of the microscopic configuration is handled using the symmetry group of the structure under consideration. An explicit form of the electromagnetic field is derived starting from a general nonlocal linear susceptibility model expressed as a low-dimensional phenomenological response function. The general form of the field obtained is used to devise new theoretical insights by providing a framework for the computation of the nanotube Green's functions.

In this paper, we study in detail both the trapped surface wave and lateral wave excited by a dipole antenna parallel to the plane boundaries of a three-layered region in spherical coordinate. An approximate formula is obtained for the solution of the electrictype pole equation when a condition is satisfied by √k²₁-k²₀l≤0.6. Similarly, an approximate formula is obtained for the solution of the magnetic-type pole equation when a condition is satisfied by √ k²₁-k²₀l-π/2≤1. Furthermore, because of its useful applications in microstrip antenna, the radiation patterns of a patch antenna with specific current distributions are treated specifically. Analysis and computations are carried out in several typical cases. It is seen that, for the component E_0Θ, the total field is determined primarily by the trapped surface wave of electric type, and, for the component E_0Φ, the total field is determined primarily by the trapped surface wave of magnetic type.

A microstrip circular patch antenna with two shorting pins is proposed as an antenna with reduced surface wave and lateral wave excitation. Theoretical analysis of the cavity modes of the patch lead to a design procedure for the antenna. Simulation results using the IE3DZeland software support the theory and verify the reduced surface wave capability. By using four shorting pins instead of two, we demonstrate the possibility of achieving circular polarization with high polarization purity in addition to the reduced surface wave. It is demonstrated that a discrimination against the lateral wave of 30dB or more is achievable. Applications include design of large patch arrays with reduced coupling and GPS receiving antennas that reduce low angle interfering signals.

This paper presents the design and construction of a complete near real-time scatterometer system for in-situ measurement. The full polarimetric system is comprised of inexpensive Frequency Modulated Continuous Wave (FMCW) radar that is efficiently constructed from a combination of commercially available components and in-house fabricated circuitry. An automated advanced antenna positioning system (AAPS) is included in the development of the system, giving rise for a more practical measurement. The backscattering matrices of a 4'' × 8'' dihedral corner reflector are rotated and measured at different angles to provide different sets of polarimetric data. The backscattering matrices of 8'' sphere, 12'' sphere and 16.5'' trihedral are also measured and the results are presented in this paper. In order to verify the effectiveness of the calibration technique, the results are compared with the theoretical values. Consideration on the challenges of measurement in outdoor environment is countered with external and internal calibration. As a result, the proposed scatterometer system has shown good correlation between measurement and theoretical results.

An improved E-plane power divider for compact waveguide triplexers with large separation between channels is presented. The configuration of the divider aims to exploit the different behavior of the device for frequency bands with large separation, leading to a very asymmetric E-plane junction. H-plane filters with inductive windows are used for each channel, in order to obtain reduced insertion losses and lower sensitivity than in metal-insert E-plane filters. The resultant triplexer configuration is very compact, and its design is analyzed and optimized by Mode-Matching. The experimental results of a full Ku-band prototype for communications satellite systems show a very good agreement with the expected simulated response.