Interior bearingless permanent magnet synchronous motors (IBPMSMs) are a new type of machines having two sets of windings in the stator, offering no lubrication and no mechanical friction, high efficiency, robust rotor construction, hybrid torque production nature and flux-weakening capability. In this paper, the suspension force modeling and the static electromagnetic characteristics of an IBPMSM are studied. The suspension force model of the IBPMSM is established and investigated based on the Maxwell tensor method. And then the static electromagnetic characteristics, including permanent magnet (PM) flux linkage, EMF, inductances, electromagnetic torque and suspension force, are discussed with the finite element analysis (FEA) method. The electromagnetic characteristics of the IBPMSM are very helpful for the design and optimization of the motor. The effectiveness of the proposed suspension force mathematical model is verified by comparing the theoretical results with FEA-based predictions. The work in this paper lays an important foundation for the optimization design and control strategies of the IBPMSM.

A double printed rotated quadrilateral dipole UWB antenna for wireless communication is presented. The rotation of quadrilateral and modification of integrated balun structure is employed to enhance bandwidth and impedance matching. The proposed antenna shows impedance bandwidth of 3.8-18.1 GHz which covers the entire C, X and Ku bands. The Radiation patterns of the designed antenna structure are relatively stable and omnidirectional over the entire obtained bandwidth with an average gain of 3.6 dB. A good agreement is found between the simulated and experimental results. The proposed antenna has a simple design, comparatively compact size and more bandwidth than previous reported double rhombus antenna.

A wideband circularly polarized (CP) slot array with high radiation efficiency is proposed. The cavity-backed square slots are designed to achieve wideband CP radiation with a unidirectional pattern. The slotted waveguide is adopted to feed the array with high efficiency. The square slot, cavity and feeding slot in the waveguide can be viewed as a radiating element. A CP slot array can be conveniently designed as traditional waveguide slot arrays, once the element admittance characteristic is determined. A 1-by-8 CP array operating at 12.5 GHz has been developed. Measured impedance bandwidth of 6.9%, axial-ratio (AR) bandwidth of 8.8% and a gain of 15.4 dBi have been achieved. This array can be conveniently expanded to a larger wideband CP array with a higher gain, which is preferred for the specific satellite communication applications.

The purpose of this paper is to theoretically investigate the properties of electromagnetic wave propagating in both one-dimensional periodic and quasiperiodic photonic crystals consisting of high-temperature yttrium barium copper oxide and strontium titanate dielectric nano-scale materials in the ultraviolet wavelength region. By using the transfer matrix method, angle-, polarization- and thickness-dependences of created PBGs are explored individually for periodic and quasiperiodic structures, and some interesting features are presented in the results section. Such supposed structures can be acts as very compact polarization sensitive splitters and defect-free multichannel narrowband tunable filters.

This paper proposes sensors based on the time-domain reflectometry (TDR) technique for qualifying ethanol fuel. Four different probe geometries were proposed: bifilar, microstrip, coaxial, and helical. All probes allowed qualification of ethanol adulterated with water. Helical probe showed the best response. Thus, this proposal contributes to the development of electronic tongues.

A W-band dual-polarized Cassegrain antenna for cloud radar is proposed. The aperture diameter of the main reflector of the antenna is 50 cm. By using a modified Magic-T structure in the feed horn, the antenna is dual-polarized with high port isolation. The measured results show that the port isolation is 44.7 dB. The gains are 47.3 dB and 49.5 dB for the two ports at 94 GHz, respectively, and the efficiency of the antenna is better than 87%.

This paper presents the design and analysis of guided wave notch filters using the Lagrangian formulation for metamaterials. It is shown that the application of the Lagrangian is a convenient and effective way to select an appropriate filtering structure and determine the necessary configuration for desired filter performance. A WR-187 waveguide horn antenna is investigated with notch filters composed of broadside coupled and gap coupled split ring resonators. It is shown that broadside coupling offers significant tunability in a compact size. The filter exhibits an operational bandwidth from approximately 3.9-5.7 GHz with 40-150 MHz of instantaneous bandwidth. The fabrication of the horn antenna and split ring resonators is presented along with simulated and measured data that confirms the approach.

A 2×2 circularly polarized (CP) MIMO antenna is proposed to resonate at 5.8 GHz IEEE 802.11 WLAN band for non-line of sight (NLOS) communication. The proposed design achieves circular polarization with two optimized 90˚ apart rectangular slots etched at the center of a truncated rectangular patch. The proposed MIMO covers 5.49-6.024 GHz frequency band. The achieved isolation between two ports is more than 33 dB. The gain at the 5.8 GHz resonant frequency is 5.34 dBi. The diversity performance in terms of gain, ECC, and MEG has been reported.

This paper presents a double-stator permanent magnet generator (DSPMG) integrated with a novel magnetic gear structure which is proposed to be used as a direct drive generator for low speed applications. Torque transmission is based on three rotors consisting of prime permanent magnet poles on the middle rotor and field permanent magnet poles on the inner and outer rotors, respectively. The proposed machine combines the function of a triple rotor magnetic gear and electrical power generator. The operating principle of the generator is discussed, and its performance characteristics are analyzed using 2-dimensional finite-element method (2D-FEM). Analysis results about its magnetic gear ratio, transmission torque, cogging torque and electrical power performance are reported. The 2-D finite element analysis results verify the proposed generator design.

In the general framework of intelligent transportation, the increasing use of information communication technology in full or hybrid electric vehicles requires careful assessment of electromagnetic compatibility, with specific reference to the conducted emissions (CE) generated by the inverter in a broad frequency range (10 kHz-100 MHz). To this aim, this work reports a modelling approach for the prediction of CE in electric powertrains, which is based on circuit representation of each single subsystem, that is, the battery, the inverter, the three-phase synchronous motor, and the power buses composed of shielded cables. The proposed models are able to represent both low-frequency functional aspects and high-frequency parasitic effects of paramount importance for CE analysis, and can be implemented into a Simulation-Programme-with-Integrated-Circuit-Emphasis (SPICE) solver. The proposed modelling approach is exploited to simulate virtual CE measurements according to international standard CISPR 25, and to investigate the impact of setup features, including grounding connections of shields, the propagation of CE in electrically long power buses, the operating point (power, torque, speed) of the motor-drive system.

A compact coupled-fed monopole handset antenna with multi-frequency band operation is proposed in this paper. It occupies a no-ground space of only 26×14mm², and two wideband operations can be achieved by the coupled-fed two opposite-direction spiral branches. The low frequency bands of LTE700 operation are achieved by two spiral branches' 0.25-wavelength monopole modes, which generate a dual-resonance mode at 740 and 780 MHz. At around high frequency ranges, a 0.25-wavelength monopole mode of a T-shaped monopole is generated at 1.75 GHz, and combined with two 0.75-wavelength high-order monopole modes of the left and right side spiral branches to cover the DCS1800/PCS1900/UMTS2100/LTE2300/2500 bands. In addition, the proposed antenna is easily printed on the dielectric surface of a low cost FR4 substrate, which makes it suitable for practical mobile applications. The proposed antenna is successfully simulated, fabricated, and measured to validate the design.

A method for extracting a desired network from the composite measurement of a desired and undesired networks combination is proposed. The desired network is required to be a reciprocal and passive network. Time-domain responses are chosen by time-domain gates according to the signal flow diagram of the measured networks. This method can be used to characterize fixtures and de-embed of fixtures effects from the composite measurement of a device under test (DUT) and fixtures combination. This method can also compensate for masking errors. Extraction for the S-parameters of the desired network are described in detail, and the extraction result is validated with two simulations.

We report the modelling and characterization of microwave absorbing materials specially designed for 26-37 GHz frequency range (Ka-band). Composite materials based on carbon nanotubes/BaTiO₃/Fe₃O₄ in a phosphate ceramic matrix were produced, and their electromagnetic response was investigated. Both theoretical and experimental results demonstrate that this material can absorb up to 100% of the power of an incident plane wave at a normal incidence angle. The physics underlying such absorption level is discussed in terms of refractive index of the material.

In this paper, a Frequency-Dependent Forward-Backward Time-Stepping (FD-FBTS) inverse scattering technique is used for reconstruction of homogeneous dispersive object. The aim of the technique is to reconstruct the relative permittivity at infinite frequency, static relative permittivity and static conductivity of the homogeneous dispersive object simultaneously. The technique utilizes iterative finite-difference time-domain (FDTD) method for solving inverse scattering problem in time domain. The minimization of the cost functional is carried out utilizing Dai-Yuan nonlinear conjugate-gradient algorithm. The Fréchet derivatives of the augmented cost functional are derived analytically with respect to scatterer properties. Numerical results for reconstruction of two-dimensional homogeneous dispersive illustrate the performance of the proposed technique.

Transmission zero behavior of two coupled sections - interdigital and combline - is investigated. It is shown that the shifting of transmission zero of any coupled-section of a particular length depends on the width of various parts and the orientation of coupled-section. Mathematical formulation has been performed to show the effect of stepped discontinuity on the transmission zero. Further, this transmission zero allocation property is used in suppression of harmonics. The idea is implemented in two types of resonators - first in parallel-coupled resonators and second in open-loop resonators. Two parallel coupled resonator based bandpass filters (BPFs) with second harmonic suppression - one of second-order and the other of fourth-order - using different coupled-sections have been fabricated, and suppression up to -30 dB and -54 dB respectively has been achieved. A fourth-order open-loop resonators based BPF with suppression of undesired passbands up to 6.3f_o has been fabricated. Further, the above property is also used to design a dual-band BPF with wide stopband without increasing the size of the filter.

Wireless power transfer system to capsule endoscope at sub-gigahertz (GHz) frequency is presented. Compact self-resonant antennas are designed to realize the transcutaneous power transfer. Experiment shows that at a distance of 5 cm, the designed system operating at 433.9 MHz can realize 1.21% power transfer efficiency (PTE) through duck intestine and porcine multilayered tissues, that is, 47.55 mW power delivered to load (PDL) at the specific absorption rate (SAR) occupational exposure limitation.

This paper proposes a fully integrated broadband power amplifier for LTE-A application using GaAs HBT process. To improve the linearity and broadband performance, RC feedback structures and dynamic bias circuits are employed and designed through optimization. With careful design of the broadband matching networks in the proposed 3-stage power amplifier topology, a power gain above 21.6 dB is achieved from 1.8 GHz to 2.8 GHz. Driven by an 80 MHz wideband LTE-A signal with PAPR of 7.5 dB, the designed RF power amplifier achieves an average output power about 22 dBm at ACLR=-30 dBc over the entire 1 GHz frequency band. Considering the broad bandwidth of the driven signal and wide frequency coverage bandwidth, the performance merits of the proposed design compare favorably with the state-of-the-art.

ƒA novel compact circularly polarized microstrip antenna (CPMA) with bandwidth enhancement is proposed and studied. By employing capacitive loading and inductive loading, the size miniaturization is achieved. The cross-shaped aperture in the ground plane is able to excite two orthogonal modes. The near-equal amplitudes and 90° phase difference between these two modes are realized by properly designing the feed network, i.e., a 0°-90° hybrid comprising a 3-dB Wilkinson power divider cascaded with a 90° phase shifter. The proposed antenna exhibits a global bandwidth of 11.5% ranging from 1.88 GHz to 2.11 GHz with an overall size 50 mm × 50 mm × 6.8 mm (0.33λ₀ × 0.33λ₀ × 0.045λ₀). The global bandwidth is defined where return loss is larger than 10 dB, broadside axial ratio (AR) smaller than 3 dB, and gain above 0 dBic.

In this paper, a coplanar waveguide (CPW)-fed dual-band slot antenna with circular polarization (CP) is presented. In order to achieve CP characteristic, an asymmetric slot and F-shaped end patch are introduced to a conventional rectangular slot antenna. Moreover, by cutting a T-shaped notch on the ground plane, the axial ratio (AR) bandwidth (ARBW) can be extended. The antenna shows left-hand CP (LHCP) radiation in the boresight direction (i.e. +Z direction) at both ARBWs. The proposed antenna is fabricated and measured. The measured results have a good agreement with the simulated ones. The measured impedance bandwidths (|S₁₁| < -10 dB) are 1.08 GHz (2.02 to 3.10 GHz, 40% at 2.70 GHz) and 2.31 GHz (4.57 to 6.88 GHz, 39.8% at 5.8 GHz). The two measured ARBWs are 600 MHz (2.60 to 3.20 GHz, 22.2% at 2.70 GHz) and at least 1.15 GHz (4.85 to 6.0 GHz, 19.8% at 5.8 GHz) at the lower and upper bands, respectively.

The Adaptive Cross Approximation (ACA) algorithm has been used to compress the rank-deficient sub-blocks of the matrices that arise in the numerical solution of integral equations (IEs) with the Method of Moments. In the context of the linear embedding via Green's operator (LEGO) method - a domain decomposition technique based on IEs - an electromagnetic problem is modelled by combining ``bricks'' in turn described by scattering operators which, in many situations, are singular. As a result, macro basis functions defined on the boundary of a brick can be generated by applying the ACA to a scattering operator. Said functions allow compressing the weak form of the LEGO functional equations which then use up less computer memory and are faster to invert.