This paper presents an improved structure of a Gysel combiner/divider suitable for high-power applications. The proposed structure makes use of stepped-impedance load line features to implement a simple, compact, low loss and sufficiently wideband Gysel configuration. It also improves isolation and facilitates design flexibility for the load location. Measurements agree with expected simulated results thus, demonstrating the proposed structure with a 10% fractional bandwidth while maintaining 20 dB of return loss and 0.25 dB of insertion loss.

An alternative representation of a Green function for electric fields on surfaces of thin impedance vibrators is proposed. The representation can be applied in software packages for simulation of RF and microwave devices. Advantages of the approach were demonstrated by analyzing the well-known problem of a thin symmetrical horizontal vibrator above a perfectly conducting plane. For a half-wave vibrator, numerical estimates of an effective external induced impedance were made for various distances between the vibrator and the plane. A possibility to realize a distribution of intrinsic impedance on the vibrator capable to compensate of the plane influence was also analyzed.

A novel UWB antenna with adjustable rejection bandwidth is proposed and fabricated. The proposed antenna consists of a monopole and a novel dual-T square resonator. The results demonstrate that a wide rejection bandwidth from 10.4 to 11.5 GHz can be achieved, and the rejection bandwidth can be adjusted by transforming the dimensions of dual-T square resonator. Moreover, reflection coefficient curve with two poles at one rejected bandwidth is also obtained which is induced by the proposed novel square resonator. In addition, to explain the mechanism of adjustable rejection bandwidth, the analysis of parametric study and electric field distributions of the design are given. The total volume of the antenna is 27 mm×19 mm×1 mm. Compared to other recent works, a simpler structure, wider rejection bandwidth and more compact size are the key features of the proposed antenna. Owing to its adjustable bandwidth and simple structure, the proposed antenna can be used in UWB communications applications to suppress the radio-frequency interference.

An electrodeless measurement technique of complex dielectric permittivity of high-K dielectric films is described. The technique is based on a quasi-optic Fabry-Perot resonator and modified for investigation of two-layer dielectric structures --- substrate/K-film. This procedure is destined to be used for providing a simple intermediate control of parameters of high-K films before the following technological process. Regimes of measurements providing the most sensitive conditions for definition of film parameters are considered. The proposed method is tested on two-layer structures with well-known parameters and is used for characterization of ferroelectric (Ba,Sr)TiO₃ films in the millimeter wavelength range (~50 GHz).

A study of the Hebron two-way radio tower in Halhul, which is part of the two-way radio network that links Bethlehem tower in the West Bank to Khan Younes tower in Gaza strip, was conducted. Hebron Tower was built over the highest spot in the region, 1027 m above the sea level. Measurements of signal power was conducted for Hebron tower and compared to various other transmitting towers seen from the area. Analysis reveals that power densities of all towers are invariably safe, and their power densities fall below international safe standards. Results show that power densities from Orange cellular tower, 3500 m away and Marah radio tower, 2350 m away from Hebron tower were indeed higher than all others measured, when all power densities were referenced back to 30 m of their respective tower antenna positions. As far as the Hebron tower is concerned, its height of 111m provides a relative safe umbrella, from electromagnetic radiation hazard, away from the main radiation beam, over the area below it.

A compact quad-band slot antenna is presented in this paper. The proposed antenna consists of ground plane, dielectric material and top radiation patch. Firstly, symmetrical L-shaped slots are inserted in a radiation patch. Then to achieve multiband performances, symmetrical square spiral slots and a snakelike area with two symmetrical arms enclosed by a long slot in the ground plane are adopted. The process of design and parametric studies are illustrated in detail. The final quad-band antenna has a small size of 0.22λ_g×0.28λ_g = 17×22 mm² (where λ_g is the guide wavelength) and covers the frequency bands from 2.39 to 2.48 GHz for lower WLAN, 3.64-3.73 GHz for downlink and 5.98-6.30 GHz for uplink standard satellite communications, and 6.97-7.18 GHz mainly used by the Indian National Satellite System (INSAT). The measured results of the proposed quad-band antenna are in accordance with simulated analysis and show good performance of return loss characteristics, radiation patterns, bandwidths and gains. Especially, with a very small size, the proposed antenna is suitable to be integrated with a portable device for varieties of wireless communication applications.

Design, optimization, and performance analysis of a three-phase field-excited flux switching (FEFS) motor to be employed for the future hybrid electric vehicle (HEV) drive applications is investigated in this paper. The stator of designed motor made of electromagnetic steels is composed of unique field mmf source and armature coils while a rotor is made of iron stack. This design has been evaluated in order to achieve power and torque density higher than 3.50 kW/kg and 210 Nm, respectively, so as to compete with the interior permanent magnet synchronous (IPMS) motor commonly installed in HEV. Given its robust rotor structure, the maximum achievable motor speed went up to 20,000 rpm. To perfect the motor design, a deterministic optimization approach was applied to meet the stringent performance requirements. In addition, experimental analyses were carried out to confirm the effectiveness of the proposed motor. Positively, the proposed FEFS motor has proved to be a suitable candidate of non-permanent magnet motor for efficient and safe HEV drive.

A low-profile wideband multiple-input-multiple-output (MIMO) antenna is presented. The proposed antenna is suitable for mobile terminals applications, as its measured -10 dB bandwidth ranges from 1.56 GHz to 2.77 GHz. The overall antenna efficiency ranges from 68% to 83% over the operating bandwidth. The overall size of the proposed antenna is 60×97×0.8 mm³. A novel isolation structure is employed to achieve isolation range of -26 dB to -16 dB. The radiation patterns are measured, and envelope correlation coefficient is evaluated. The simulated and measured results are in good agreement.

This paper describes the concept and design of a novel compactself-supported cup feedantenna for parabolic reflectors. The feed antenna consists of an open waveguide cup which is excited by a disk loaded dipole. This structure is fed by a coaxial waveguide through a split-coaxial balun and has a rear radiation pattern toward the reflector antenna. Two different types of this configuration are designed in this paper: a linearly-polarized grid reflector antenna fed by a single dipole excitation, and a circularly-polarized solid reflector antenna fed by a cross dipole excitation. The measurement is done for the former, and simulation results of the latter via two different software packages CST and HFSS are compared in this paper. Analyzing the results shows that both types of cup feed antenna have an excellent aperture efficiency and low side lobe level.

A highly efficient hybrid method of single integral equation (SIE) and electric/magnetic current combined field integral equation (JMCFIE) is presented, named as SJMCFIE, for analysing scattering from composite conductor and dielectric objects, in which, SIE can reduce one half unknowns in dielectric region. The resultant matrix equation of SJMCFIE can be represented in the iteration form, which makes the computation complexity reduced further, and coupling mechanism of composite model becomes more explicit. For accelerating matrix-vector multiplications (MVMs), Multilevel Fast Multipole Algorithm (MLFMA) is employed to combine SJMCFIE to formulate SJMCFIE-MLFMA at last, which is the extension of SIE-MLFMA in the proposed reference. Finally, some examples verify the new hybrid method on accuracy, memory storage, computation efficiency compared to SIE-MLFMA and JMCFIE-MLFMA. Besides, SJMCFIE-MLFMA can also be used to analyse the complete coated model's scattering.

In this paper, we propose a systematic simulation-based approach to estimate the reading distance of an RKE system. In our electromagnetic (EM) simulation, a receiving RKE antenna and a vehicle structure, including both exterior and interior, are modeled as piece-wise mesh triangles to obtain accurate radiation characteristics of the antenna mounted inside the vehicle. The reading distance is then estimated by a two-ray propagation model that includes effects of space loss, ground properties, and antenna polarizations for various orientations and heights of handheld devices. The estimated distances are compared to the measurement, and results show that the proposed approach is suitable to replace the measurement-based approach with an average error of less than 2 m.

The main section of this paper comprehensively analyzes electrical shielding effectiveness (ESE) of enclosures with rectangular apertures for producing valuable information used in electromagnetic interference and compatibility guiding enclosure designers of electronic devices. Firstly, results of conventional analytical equivalent circuit model, measurement and simulation with computer simulating technology (CSTTM) of ESE for an enclosure with a single aperture size are compared to improve closeness in different models at 0-1 GHz. After getting a suitable simulation model, all possible parameters with detailed cases are examined to approach beneficial conclusions. Especially, size of enclosure, aperture size, aperture shape, configuration and number of apertures, probe position parameters that affect ESE are investigated. Also, some double parameters are analyzed together to achieve detailed review as two enclosure dimensions, two aperture dimensions and probe position with enclosure depth. Therefore, three-dimensional graphical investigations are performed. Obtained results of these parametric approaches are explained with acceptable reasons. Finally, detailed and itemized comments are given about simulated results of ESE parameters, which are collected from previous sections.

A planar wideband balun is proposed. The proposed balun consists of a novel slotline T-junction and three microstrip-slotline transitions. Similar to the principle of the E-plane waveguide T-junction, the slotline T-junction acts as a phase inverter. With the microstrip-slotline transition, the device employs microstrip as feedlines. The radiation loss of the slotline is reduced to improve the insertion loss by loading the slotline with a superstrate and adding via holes along the slotline. An experimental balun with a bandwidth of 128% from 2.2 GHz to 10 GHz is designed, fabricated, and measured for validation. The measured results have reasonable agreement with the simulated ones.

An analytic model is proposed to estimate the electromagnetic field transmission line coupling for both radiated emission and immunity using TEM cell measurements. Further, a coupling impedance is introduced to determine the domination between electric and magnetic fields of the field-line coupling. Comparison of measurement and calculation results confirms the accuracy of the model. The model and coupling impedance can be helpful for the suppression of radiated emission and the enhancement of radiated immunity of transmission lines in electromagnetic compatibility design of electronic systems.

A benchmarking procedure for sparse linear array synthesis methods is proposed. Our approach is based on the comparison of the performance of the array synthesis algorithm under test with the performance of a reference equispaced array. The benchmark procedure is discussed considering some examples regarding sparse synthesis method proposed in literature. Guidelines for the correct comparison of synthesis methods and some ``tough problems'' for the test of new sparse synthesis algorithms are also provided.

An ion beam propagating through a magnetized plasma having positive ions K⁺ (Potassium ions), electrons and negative ions SF₆^- (Sulphur hexafluoride ions) drives Kelvin Helmholtz Instability (KHI) via Cerenkov interaction. For two modes, K⁺ and SF₆^-, the frequency and the growth rate of the unstable wave increase with the relative density of negative ions. It is observed that the beam has destabilizing effect on the growth rate of KHI in the presence of negative ions. However, at the large concentration of the negative ions beam stabilizes the growth rate of KHI. An increase in mass of negative ions also stabilizes the growth rate of KHI modes. It is also observed that increase in ion beam velocities and densities play a significant role in changing the growth rate of KHI modes. Moreover, the finite geometry effects tend to modify the dispersion properties and growth of KHI modes.

The corrosion and anti-corrosion current of a ship modulated by the shaft can be equivalent to a time-harmonic current. Based on Maxwell's equations and boundary conditions of electromagnetic field, the Helmholtz equation of magnetic vector potential and the magnetic field expressions of the time-harmonic current in air are deduced. Then, the fast Hankel transform filtering algorithm is applied to solve the equations which contain Bessel integral. The theoretic calculation indicates that the magnetic induction intensity and its attenuation rate decrease along with the increase of distance. The three components of magnetic field have different distribution. At last, it is verified that the shaft-rate magnetic field can be observed by the experiments of carbon electrodes and ship model carried in a sea pool.

In this paper, hyperbolic metamaterials slot waveguides based on graphene have been proposed to explore the optical characteristics. The hyperbolic metamaterials are composed of graphene-dielectric alternating multilayer. It has been verified in our proposed structure that the optical field is enhanced efficiently in the slot region, which results in the optical gradient force becoming larger as the distance of slot region becomes smaller. Both numerical simulation and theoretical analysis systematically reveal that the stronger gradient force can be achieved through smaller slot gap or lower chemical potential. Furthermore, the optical properties of two coupled waveguides have been studied under the relation of incident wavelength, chemical potential of graphene, composition of graphene-dielectric multilayer (eg., number of periods, filling factor of graphene) of the waveguides in this work. We find that a larger gradient force can be obtained by adjusting the height of waveguides, either decreasing the thickness of dielectric with constant number of periods or compressing the number of periods with fixed graphene filling factor. Our results will be helpful to the study of the optical field in the infrared region and also has great potentials in nanoscale manipulation and plasmonic devices.

In this paper a multiple input multiple output (MIMO) radio channel measurement system is presented that utilizes several software defined radio (SDR) platforms at the transmitter and at the receiver. The system hardware buildup and its calibration technique are presented. The channel measurement results are afterwards exploited for a special antenna synthesis method that was already proofed by raytracing channel simulations. The antenna synthesis method is applied to a mobile single and to a mobile multiple channel receiver. The resulting synthesized antenna systems are evaluated in terms of antenna radiation patterns and the corresponding channel capacities. The results reveal the superiority of synthesized antenna systems compared to conventional omnidirectional antenna systems in the considered urban street scenario. Moreover, the findings from the antenna synthesis based on dynamically measured MIMO radio channels confirm the results from the raytracing channel simulation based antenna synthesis.

A wide-band single-layer EMI shielding material for X-band is developed using an M-type strontium hexa-ferrite nanoparticle filler in LLDPE matrix. Strontium hexa-ferrite nanoparticles with crystalline size of 25.8 nm are obtained by annealing at 850˚C. LLDPE allows a higher wt. % of ferrite inclusions enabling enhanced dielectric and magnetic losses. A peak absorption of 99.39% is achieved at 10.21 GHz when the filler weight in a 3 mm thick sample is adjusted to 60 wt.% while a wide -10 dB absorption bandwidth of 3.36 GHz centered around the same frequency is obtained. The density of the composite is 1.36 g/cm³ and shows negligible water absorption.