This paper describes the performance characteristics and comparison results of three different types of two-phase switched reluctance motors (SRM). This collection includes conventional, stepped rotor and slanted rotor two-phase SRMs. These motors have four stator poles and two rotor poles, named 4/2 configuration. The main difference between these configurations is their rotor structures. The number of turns and areas of all stator pole faces jointly involving in torque production mechanism in the motors are taken to be equal. The terminal inductance per phase, flux linkage of each stator pole winding, and components of leakage inductances are determined and plotted for different rotor positions and excitation currents. Finally, the static torque for different forced current levels and rotor positions are also presented for each motor.

A broadband monolithic image rejection subharmonic mixer using a standard 0.18 μm CMOS technology is proposed. This circuit is composed of a band-pass filter with an intermediate frequency (IF) extraction function that can simplify the block diagram of the image rejection mixer. The entire passive circuit is constructed using a broadside coupling structure to achieve a high level of integration. Based on measured results, the proposed mixer exhibits conversion loss of 15.5-18.5 dB at a local oscillator (LO) power of 13 dBm, whereas the 3 dB bandwidth ranges from 20 to 31 GHz (43.1%) with a miniature chip dimension of 0.77×0.81 mm². The LO-to-radio frequency (RF), 2LO-to-RF, and RF-to-IF isolation levels are higher than 22.5, 42.9, and 34.5 dB, respectively. The best image rejection ratio of 29 dBc with 20° phase compensation at 24.5 GHz can be achieved.

In this paper, a compact notched ultra-wideband (UWB) bandpass filter with improved out-of-band performance using quasi electromagnetic bandgap (EBG) structure is proposed. Firstly, a UWB bandpass filter based on a stepped-impedance stub-loaded resonator (SISLR) is combined with quasi-EBG structures, which suppress the undesired spurious bands to improve the out-of-band performance. In order to eliminate the interference caused by WLAN, a notched band is introduced at 5.2 GHz, which is implemented by adding a folded stepped-impedance resonator (SIR) near the stub of the SISLR. At last, the proposed filter is fabricated and measured. Good performances of the UWB filter have been demonstrated both in the simulated and measured results.

In this paper, an analytic frequency domain method based on Taylor's series expansion approach is introduced to analyze inhomogeneous planar layered chiral media for an arbitrary linear combination of TM and TE polarizations. In the presented method, electromagnetic parameters of inhomogeneous chiral media and also the electric and magnetic fields are expressed using Taylor's series expansion. Finally, the validity of the method is verified considering some special types of homogeneous and inhomogeneous chiral media and comparison of the obtained results from the presented method with the exact solutions.

This paper deals with the challenges related to evaluating the performance of Multiple Input Multiple Output (MIMO) antenna based on Long Term Evolution (LTE) system within an underground mine environment at 2.4 GHz. Actual measured channels parameters have been used in simulation tools based on Agilent SystemVue software. The results suggest that LTE is able in practice to support multi stream transmission with very high data rates in an underground mine gallery.

A complete methodology is employed to determine the transmission characteristics of low-voltage/broadband over power lines (LV/BPL) channels associated with underground power distribution networks, in the light of the multiconductor transmission line (MTL) theory. The established bottom-up approach, already used to treat overhead and underground MV/BPL transmission, is extended to analyze BPL transmission in three-phase N-conductor underground lines with common shield and armor. This analysis shows that these cables may support N + 2 modes, giving rise to N + 2 separate transmission channels which reduce to N + 1 if the armor either does not exist or is grounded and to N if the shield is also grounded. In addition to the generalized analysis, a simplified approximation concerning three-phase N-conductor underground cables is also presented. Taking the generalized analysis and the simplified approximation into account, their numerical results concerning attenuation in various underground LV/BPL channels in the frequency range 1-100 MHz are validated against relevant sets of simulations and measurements with satisfactory accuracy and compared to corresponding results of overhead and underground MV/BPL channels. It has been verified that the attenuation in overhead and underground BPL channels depends drastically on power distribution grid type, MTL configuration, and cables used. Moreover, the attenuation in underground LV/BPL channels exhibits a lowpass behavior, is significantly higher than that of overhead MV/BPL ones, and is comparable to that of underground MV/BPL ones. A consequence of the proposed methodology is that it can facilitate the integration process and intraoperability of LV/BPL and MV/BPL systems through their common physical layer handling.

Two dimensional metallic photonic band gap (PBG) structures, which have higher power handling capability, have been analyzed for their dispersion characteristics. The analysis has been performed using finite difference time domain (FDTD) method based on the regular orthogonal Yee's cell. A simplified unit cell of triangular lattice PBG structure has been considered for the TE and TM modes of propagation. The EM field equations in the standard central-difference form have been taken in FDTD method. Bloch's periodic boundary conditions have been used by translating the boundary conditions along the direction of periodicity. For the source excitation, a wideband Gaussian pulse has been used to excite the possible modes in the computational domain. Fourier transform of the probed temporal fields has been calculated which provides the frequency spectrum for a set of wave vectors. The determination of eigenfrequencies from the peaks location in the frequency spectrum has been described. This yields the dispersion diagram which describes the stop and pass bands characteristics. Effort has been made to describe the estimation of defect bands introduced in the PBG structures. Further, the present orthogonal FDTD results obtained have been compared with those obtained by a more involved non-orthogonal FDTD method. The universal global band gap diagrams for the considered metal PBG structure have been obtained by varying the ratio of rod radius to lattice constant for both polarizations and are found identical with those obtained by other reported methods. Convergence of the analysis has been studied to establish the reliability of the method. Usefulness of these plots in designing the devices using 2-D metal PBG structure has also been illustrated.

A wave-based inversion algorithm for the recovery of deviation in he values of elements of discrete lossless inductance-capacitance and capacitance-inductance ladder networks from their nominal values is formulated. The algorithm uses ultra wideband source excitation over the frequency range where forward and backward voltage and current waves propagate along the network. Employing a weak type scattering formulation renders the voltage wave reflection coefficient to be a Z transform of the sequence of perturbation in the value of the elements. Inversion of the reflected date from the transformed domain to the spatial domain by Fourier type integration yields the element's perturbations and consequently, the actual elements of the network. Demonstrations of the algorithm performance on several test cases show its efficacy as a non-destructive testing tool.

An integrated Terahertz {Mach-Zehnder} interferometer is presented in order to perform differential measurements in a chip. Both simulation and experiment are performed for validating the interferometer structure. Destructive interference peaks are observed, and destructive frequencies are predicted by a mathematical model with a good agreement. The structure is then used to characterize dielectric constant of materials. Simulation results enable to quantify the device sensitivity. An experimental validation is given with the characterization of a thermosensitive polymer (Cyclotene BCB) in the sub-THz frequency band. Perspectives to increase investigated frequencies are discussed.

A novel class of surface magnon polaritons supported in identical enantiomeric antiferromagnetic structures is presented. The surface waves arise due to bianisotropy. The existence of two distinct surface modes with unusual dispersion and polarization properties is predicted. The role of losses is investigated and the propagation length of the surface waves is determined.

Bacteria exist in a variety of groups of shapes, sizes, and single or multiple cell formations. In this paper, the level set shape reconstruction technique, the method of moments, and the marching cubes methods are integrated in the high frequency band for imaging three dimensional bacteria. The time step and the resolution of the marching cubes method are investigated to smooth the error function of the level set and hence speed up the convergence at high frequencies. The numerical results demonstrate the robustness of the level set algorithm for the detection of bacteria based on their shapes. The three dimensional shape reconstructions of unknown bacteria can be utilized to classify biological warfare agents.

A uniplanar corner-fed patch antenna is presented with single-point microstrip feed and single layer substrate. Two orthogonal polarized dominant modes TM010 and TM001 are excited at two different frequencies. By utilizing a corner-fed structure, impedance matching for two bands can be adjusted much independently and the small ratio between two operating frequencies is easy to achieve. In addition, this simple and compact structure makes the patch antenna very convenient to form an array. A patch antenna operating at 12.5 GHz and 14.25 GHz with two linear orthogonal polarizations has been designed. The frequency ratio is only 1.14. The return loss, current distribution and radiation patterns of the patch element are investigated in detail. An 8 by 8 array has been developed, of which gains more than 23.4 dBi have been obtained at dual frequencies. Measured results agree well with simulated ones, which validate the proposed structure.

This paper presents a two-port antenna including a receiving port and a transmitting one in the same volume. These two antennas are physically integrated and electrically isolated. The receiving antenna is a linearly polarized narrowband slot for energy harvesting, whereas the transmitting one is a circularly-polarized ultrawideband (UWB) quasi-spiral for signal radiation. The measurement results show that, the slot resonates at 5.8 GHz, and the quasi-spiral has a 10-dB return loss bandwidth of 2.85-5.16 GHz and a 3-dB axial ratio bandwidth of 3.05-4.43 GHz. The electrical isolation between these two antennas is more than 20 dB covering 1-8 GHz. This two-port antenna is a good candidate for wireless-powered UWB-RFID tags.

In this article, a low cost, simple, and compact printed microstripfed U-shape monopole ultra-wideband antenna with dual band-notched characteristics is proposed and investigated. By introducing a spiral shaped λ/4 open stub in the microstrip feed line and a pair of L-shaped slots on the rectangular ground patch, dual band notched characteristics can be obtained respectively. The proposed antenna is successfully simulated, designed, fabricated and measured. The measured results show that the proposed antenna with dimensions of 24 mm (W_sub) × 34 mm (L_sub) × 1.6 mm (H) has a large bandwidth over the frequency band from 2.75 GHz to 10.6 GHz with VSWR less than 2, except 3.27-4.26 GHz and 5.01-5.99 GHz frequency bands. The proposed antenna exhibits nearly omnidirectional radiation pattern, stable gain, and small group delay variation over the desired frequency bands.

This paper deals with the evaluation of the electric and magnetic field generated by a set of N periodically distributed filamentary conductors, in a circular arrangement. The results obtained lead to the computation of a continuous product of distances. In close connection with the computation of such a continuous product, the general problem of the factorization of a sum or difference of two powers, a^N±b^N, where a and b are positive real numbers and N a positive integer, is addressed.

In this paper, a new method is proposed to estimate the simultaneous switching noise (SSN) directly from the power delivery network (PDN) frequency-domain impedance in order to reduce the time-domain simulation of SSN and computational burden, which is based on the periodic characteristics of the switching current and the SSN produced by one current pulse. The frequency-domain impedance is approximated with several single resonance circuits, which can capture the resonance characteristics of the PDN. The parameters of each resonance circuit are calculated with the rational function. It is also found that the SSN can be suppressed through adjusting the resonant frequencies and the period of switching current. Compared with the single resonance lumped circuit model and multi-resonance distributed circuit model, the performance of the new method for estimating the SSN is verified, which is more accurate than the target impedance method.

Based on the magnetocaloric effect, magnetic refrigeration at room temperature has, for the past decade, been a promising and environmentally friendly technology predicted to have a significantly higher efficiency than the present conventional methods. However, to the authors' knowledge, so far no prototypes have been presented for large scale applications. This paper presents the modeling of a superconducting-based magnetic refrigeration system for large scale applications. On one hand, electromagnetic computations are undertaken to maximize magnetic field produced in order to get the best performance (temperature span and cooling power) and to limit the mechanical efforts (forces and torque). On the other hand, the thermal modeling aims to evaluate and to optimize the cooling performance.

Split-field finite-difference time-domain (SF-FDTD) meth-od can overcome the limitation of ordinary FDTD in analyzing periodic structures under oblique incidence. On the other hand, huge run times of 3D SF-FDTD, is practically a major burden in its usage for analysis and design of nanostructures, particularly when having dispersive media. Here, details of parallel implementation of 3D SF-FDTD method for dispersive media, combined with total-field/scattered-field (TF/SF) method for injecting oblique plane wave, are discussed. Graphics processing unit (GPU) has been used for this purpose, and very large speed up factors have been achieved. Also a previously reported formulation of SF-FDTD based on the Drude model for dispersive media, is extended to cover Drude-Lorentz model, which is usually needed for materials such as gold. The resulting reduction in the number of variables in this formulation, not only helps in reducing the computational time, but also makes it possible to be implemented in GPU, where its memory limitation is a major concern. As an example for demonstrating the importance of this method in optimization of nanophotonics structures, improvement in the performance of a refractive index sensor, made of an array of nanodisks, using suitable angle of incidence is reported. To the best of our knowledge this is the first report of GPU implementation of SF-FDTD method, capable of analyzing periodic dispersive media under oblique incidence.

Closed-form mixed potential Green's functions (MPGFs) for cylindrically stratified media are derived in terms of quasistatic-wave and surface-wave contributions. In order to avoid possible overflow/underflow problems in the numerical calculations of special cylindrical functions such as Bessel and Hankel functions, a novel form of the spectral-domain MPGFs is developed. Then, a two-level methodology is used for the approximation of the spectral-domain MPGFs. In the first step, the qusistatic components are extracted from the spectral-domain MPGFs, and then transformed into the space domain with the use of the Sommerfeld identity and its derivatives. In the second step, the remaining parts of the spectral-domain MPGFs are approximated in terms of pole-residue expressions via the rational function fitting method (RFFM). The proposed method is efficient and fully automatic, which avoids an analytical cumbersome extraction of the surface wave poles (SWPs), prior to the spectrum fitting. In addition, this method can evaluate the spatial-domain MPGFs accurately and efficiently for both the near- and far-fields. Finally, numerical results for the spatial-domain MPGFs of a two-layer structure are presented and discussed.

In this paper, a new look at the electromagnetic field in a reverberating chamber (RC) is presented. It follows the fractional Brownian motion (fBm) model and exploits the Hurst parameter as the key parameter to discriminate among various RC configurations. Experiments accomplished at the RC of the Università di Napoli Parthenope, formerly Istituto Universitario Navale (IUN), confirm the physical soundness of the proposed model.