An efficient numerical solution is presented for computing per-unit-length impedance of metallic rectangular transmission lines backed by semi-infinite lossy substrate. We formulate the problem into the set of integral equations, the kernel of which is analytically expressed in terms of special functions in the quasi-static regime. The method of moments is applied to find the current density distributions in the metal regions, where the discretization of cross sections is performed by using non-uniform grid arranged according to the skin effect. The practical numerical computations concern the influence of the substrate loss on the per-unit-length impedance for some types of parallel lines. We thereby show that the substrate loss cannot be neglected at high frequencies. The effectiveness of the proposed method is confirmed by showing that the computed values of resistance satisfy the law of energy conservation with acceptable accuracy.
This work presents a compact, high performance GaAs V-band bandpass filter (BPF) using a slow-wave coplanar waveguide transmission line (S-CPW TLine) and a CMRC (compact microstrip resonant cell). The slow-wave CPW Tlines have potential for the use in miniaturized low loss compact passive devices in the millimeter-wave frequency band. Owing to strong slow-wave effect, the longitudinal length of the S-CPW is shorter than that of a classical microstrip based on the same technology. The S-CPW TLines in the designed filter were realized with a reconfigurable defected ground structure (DGS). Adding the conventional inductively coupled resonator CMRC BPF allows the resonator to be miniaturized by the exploitation of the transversal dimensions of the CPW, while maintaining its performance as measured by insertion and return losses. However, the DGS cell allows reconfiguration of the structure from a low-band to a high-band BPF. The design of the filters with the DGS using filters that are designed for V-band applications is explained.
Our main objective in this article is to achieve minimum side lobe levels for a specific first null beam-width and also a minimum size of the circumference by an optimization-based design method for non-uniform, planar, and circular antenna arrays. Our approach is based on a new variant of Particle swarm Optimization technique. This new technique is a hybrid of Local Neighborhood based PSO with Hierarchical PSO Algorithms termed as Hierarchical Dynamic Local Neighborhood Based PSO (HDLPSO) Algorithm. Three difficult instances of the circular array design problem have been presented to illustrate the effectiveness of the proposed HDLPSO algorithm. The design results obtained with HDLPSO have been shown to comfortably beat the results obtained with other state-of-the-art meta-heuristics like Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Invasive Weed Optimization (IWO) and Differential Evolution (DE) in a statistically significant manner.
Three dual band planar monopole antennas for wireless local area network (WLAN) application are proposed. The antennas have common configuration in the form of rectangular, rhombic and annular double rings. All the antennas use the self similarity property to exhibit dual band characteristics. The proposed antennas covers the frequency bands of the IEEE 802.11a/b/g (2.4-2.48 GHz, 5.15-5.35 GHz and 5.725-5.825 GHz), and have radiation patterns that are; almost omnidirectional in the H-plane, and like monopole pattern in the E-plane. The simulation results are analyzed and compared with measured results for verification.
In this paper, we present the chaotic verification for angular glint of complex radar target. Angular glint is a key factor in the generation loss probability in radar detections, and the intrinsic physical characteristic and suppression techniques of glint have been a hot topic in radar signal analysis. In this paper, the radar angular glint samples of a typical complex target are calculated by the Greco method based on Phase Gradient method. The simulated glint series fit the prerequisites of chaos for deterministic, nonlinear generation and no regularities in time domain, therefore the analysis the chaotic traits is required. We propose the design of chaotic verification flow, which is proved to be efficient and effective by the experiment of Lorenz Attractor signal model, and the details have been explained. The algorithm flow begins with the determination of optimum time lag and minimum embedding dimension, and is followed by the time-delay reconstruction in phase space. The results are presented with three qualitative verification results of attractor geometry, Poincare section and principal component analysis and two quantitative results of correlation dimension and largest Lyapunov exponent for the glint series. With comparison with results obtained by Lorenz attractor, the chaotic traits of angular glint data are verified. Therefore, the paper has proposed new possible reduction and prediction ideas to refrain angular glint in the digital processing unit of radar receiver in the future.
The paper presents the description of multiply connected conducting regions (MCCR) in the finite elements space. In order to define induced currents distribution in multiply connected regions, an innovative method of combined vector potentials T and T0 has been suggested. The equations of T-T0 method have been presented. Moreover, the relations describing sources for the field of induced currents in the discussed regions have been given. The proposed method has been applied to solve Problem No. 7 of the International TEAM Workshops. The selected results of calculation have been compared with the measurement results.
When a magnetic source is moved and/or oscillating above a conductive linear plate a traveling time varying magnetic field is created in the airgap. This field induces eddy currents in the plate that can simultaneously create normal and tangential forces. The transient fields and the forces created by the magnetic source are modeled using a novel 2-D analytic based A-Φ method in which the presence of the source field is incorporated into the boundary conditions of the plate. The analytic based solution is obtained by using the spatial Fourier transform and temporal Laplace transform. The performance of the method is compared with a 2-D transient finite element model with a Halbach rotor source field. The derived transient force equations are written in a general form so that they can be applied to any magnetic source.
This paper proposes a new 3-phase flux-switching permanent-magnet (FSPM) motor, termed as modular FSPM (M-FSPM) motor, for high reliability applications. Due to PMs in the stator, the proposed motor offers high efficiency, simple and robust rotor structure, and good thermal dissipation conditions. The key is the new motor topology which incorporates the concept of fault-tolerant teeth to provide the desired decoupling among phases. By using finite element method, the proposed M-FSPM motor is analyzed as compared with the existing fault-tolerant FSPM (FT-FSPM) motor. The results show that the proposed M-FSPM motor not only retains the merits of high power density, strong mechanical integrity, good immunity from thermal problem and high torque capability, but also offers lower torque ripple, higher average torque and lower cost than the existing FT-FSPM motor. A proposed M-FSPM motor is designed and built for exemplification. Experimental results of the prototype are given to confirm the validity of the proposed motor.
An acceleration technique for the MoM solution of large-area metamaterial arrays is proposed that relies on numerical extraction of the modal profile associated with the individual array elements followed by projection of the global system equations onto a judiciously constructed reduced solution space. To further enhance the performance of the underlying MoM computations an IE-FFT engine is developed that is adapted for the underlying JMCFIE formulation and higher order quadrilateral discretization. A number of large-area metamaterial arrays are solved and the computational statistics are presented to reflect the advantage of the the proposed methodology.
In this work, the influence of human body within the estimation of dosimetric values is analyzed. A simplified human body model, including the dispersive nature of material parameters of internal organs, skin, muscle, bones and other elements has been implemented. Such a model has been included within an indoor scenario in which an in-house 3D ray launching code has been applied to estimate received power levels within the complete scenario. The results enhance previous dosimetric estimations, while giving insight on influence of human body model in power level distribution and enabling to analyze the impact in the complete volume of the scenario.
In this paper, we propose an approach for designing and quantitatively assessing the performance of the multilayered radar-absorbing structure. In our proposed approach, a five layered radarabsorbing materials design is optimized from the predefined materials database. But to determine the optimal choice of the material and thickness of each layer, a combined binary and real-coded genetic algorithm (GA) is used to handle the integer and real variables involved in such designs. Further, the proposed approach employs the Latin hypercube sampling with Monte Carlo Simulation to carry out the performance based reliability analysis of the design. Absorber synthesized results are compared with the published work using other algorithms. The outcomes of our approach show that the combined GA works quite well, and most prominently the reliability analysis provides the decision maker a means to select among the several design alternatives available before him.
In this paper a low cost, high gain, low cross-polar and compact edge feed printed elliptical antenna with a partial ground plane and parasitic patches is proposed and investigated. The proposed antenna is backed by partial ground and parasitic patches. It is fabricated on 1.6 mm thick FR4 substrate with dielectric permittivity of 4.4 and tanδ of 0.025. The total planar area of the proposed antenna (L x W) is 28 mm x 24 mm. Both the simulated and experimental result shows that the proposed antenna provides a frequency range compatible with the ultra-wideband (UWB) standard, i.e., 3.5 GHz-12 GHz frequency band. The radiation pattern produced by the proposed antenna is approximately omnidirectional with in-phase excitation of Surface waves resulting in less cross-polarization level (less than 20 dB) compare to its co-polar component for complete impedance band width. The maximum measured gain for the fabricated antenna is around 6.27dBi with an average efficiency of above 90% throughout the bandwidth. A linear phase response (phase S21) accompanied by a constant group delay of 1ns throughout the measured bandwidth makes the proposed antenna a good candidate for UWB applications.
The classical transmission line theory is expanded to include convection current flow and electromagnetic radiation in unbalanced transmission lines. A theory for the generation of the nonlinear convection current in unbalanced transmission lines is developed. The convection current and the radiation parameters are included in the transmission line equations and a generalized transmission line theory is developed.
This paper studies the characteristics of a constant-K lens when considered as a possible substitute for a Luneburg lens in a reflector. The competitiveness of the substitute lens is investigated in its 2D analogue, by comparing the backscattering radar cross section for the range of D/λ ∈ (0, 200). The performance of cylindrical reflectors with either a constant-K lens or a cylindrical Luneburg lens (approximated by a finite number of stepped-index dielectric layers) when illuminated by an electromagnetic plane wave is studied using the semi-analytic Method of Regularization. Because of similar underlying physical principles, these studies provide insight into the 3-D analogue. The radar cross section calculations of the two reflectors for incidence angles varying from normal to grazing incidence show that the cheaper-to-manufacture constant-K lens reflector is able to provide a more powerful and stable backscattering performance than the cylindrical Luneburg lens reflector, for electrical sizes in the range considered.
A convenient method for canceling the parasitic winding capacitance of integrated electromagnetic interference (EMI) filter is proposed. Based on the concept of split ground structure, mutual inductances and structural capacitances can be appropriately utilized to expand the effective frequency range in common mode (CM) noise suppression. Compared with the former approaches, it requires no additional conductor layers or components since the split winding can simultaneously serve for CM capacitance. To demonstrate the parasitic capacitance cancellation mechanism, a simplified equivalent circuit is derived and investigated. Besides, the design procedure with considered structural constraints is presented to obtain the best parasitic capacitance cancellation effect. Prototype of an integrated CM filter with split ground layers is designed and constructed. Experimental results show the split winding can effectively shift the resonance frequency of filter inductor, and hence better filtering characteristics can be achieved.
Traditional detection approaches for the dim moving target are addressed under the background of homogeneous sea clutter. However, the realistic clutter commonly appears inhomogeneous, resulting in the low detectability. A heterogeneous multiple-scan detection framework is described in this paper, which combines the inhomogeneous coherent integration in the dwell of single scan and the non-coherent integration of the results from single-scan process across the multiple scans. In the inhomogeneous coherent integration, the Heterogeneous Single-scan Coherent Detector (HSCD) is derived, resorting to the two-step Generalized Likelihood Ratio Test (GLRT) criterion and a hybrid covariance matrix estimation scheme, where the nonhomogeneous Kelly detector and the inhomogeneous Adaptive Matched Filter (AMF) are also considered. Additionally, the Viterbi-Like (VL) algorithm is employed as the noncoherent integration strategy. Finally, the numerical simulations with Monte Carlo method analyze the performance of the nonhomogeneous multiplescan detectors under amplitude and distribution clutter heterogeneity.
Maximizing the Radio Frequency Identication (RFID) performance is one of the main challenges in application domains, such as logistics and supply chain management, where the undesired effect of Tag collisions can significantly degrade the speed of the inventory process. The dominating UHF EPC Class-1 Generation-2 (EPC Gen2) protocol only specifies collision avoidance algorithms but makes no provision for collision resolution. In this paper, performance enhancement of the EPC Gen2 standard exploiting Tag collision recovery is demonstrated, for the first time, in real time with measurements. Three simple and effective approaches to handle successful Tag acknowledgments of recovered collided packets are proposed and implemented on a software-defined Reader and programmable Tags. The attained benefits over the conventional EPC Gen2 MAC scheme are significant: the throughput per time slot is increased by 72% while the overall time required to inventory the Tag population is reduced by 26%. The effectiveness of the proposed approach and the validity of the achieved results are confirmed by the good agreement with simulations reported in the literature.
A new technique for broadband material characterization, using a whispering-gallery-mode (WGM) resonator, is proposed. The resonant perturbation method is applied for the measurement of both the dielectric constant and loss tangent of various types of materials and over a wide frequency band. A comprehensive study on the reliability of using such technique, via simulations and measurements, is conducted as well. The feasibility of this device in sensing small variations of the dielectric properties of the material is investigated. Furthermore, the geometry of the resonator is slightly modified to fit liquid materials as well. This can be a promising solution for sensing human-body tissues or liquids such as blood or urine due to the sensitive nature of these resonators. The experimental setup is successfully utilized to measure the dielectric constant of a water droplet as a liquid sample as well as different material samples of arbitrary shapes and dielectric properties. The measurements are performed over the whole X- and K-bands where the obtained results are with a maximum deviation of only 3.3% for solids and 4.5% for liquids.
In microwave induced thermo-acoustic tomography (MITAT) system, radiation of an antenna is a near field problem which gives rise to a non-uniform distribution of microwave radiation power in detection area. Due to this non-uniform distribution, the contrast of MITAT image which is proportional to the absorbed microwave energy will not reflect the real characteristics (dielectric properties) of biological tissues. In this paper, an image correction method based on electromagnetic simulation is proposed to correct the image contrast affected by the non-uniform microwave radiation distribution. First, the distribution of the microwave radiation power is simulated through a numerical simulation framework. Conventional time-reversal mirror (TRM) technique is applied to reconstruct the image. Then the microwave power distribution is applied to correct the image. The method is numerically demonstrated. The two samples with the same microwave absorption property and with different microwave absorption properties are experimentally investigated. Both numerical simulations and experimental results demonstrate the good performance of the proposed method.
This paper presents an end-user evaluation of aircraft detection and identification capacity of the surveillance system deployed in terminal 4 apron of Madrid-Barajas international airport. The main goal of the system is to provide real-time surveillance information about aircraft and vehicles on the apron area, including stands, facilitating airport operation centre tasks concerned with delay minimizing and apron resources use optimizing. In order to describe system performance, a set of indicators are defined to quantify the output information reliability and to measure the capabilities of this system to automate routine airport operations.