The objective of this paper is to propose an improved approach based on a novel non-intrusive method for easily assessing the high frequency CW EM radiated susceptibility of an electronic system by characterizing its nonlinear electromagnetic effects. For this purpose, we have developed a specific harmonic frequency detection system coupled with a mode stirrer reverberating chamber. We describe the principles of the method and study a generic device board which is representative of a real electronic system. We evaluate the EM susceptibility of a micro controller in full functional mode and the data exchanges with two types of external 8 Mb SRAM memories. We observe the EM radiated susceptibility of this device by a functional EMC analysis method; then we measure the harmonic frequency content and make a correlation with the EM susceptibility results. We obtain significant differences between the two memory devices, as a consequence of their different managements of internal voltage over stress. We are well aware that this method is currently not validated in industrial environments EMC. In this paper, we only want to show that the appearance of the highest harmonic level occurs only when DUT has the highest functional failure.

We apply the Gabor frame as a projection method to numerically solve a 2D transverse electric-polarized domain-integral equation for a homogeneous medium. Since the Gabor frame is spatially as well as spectrally very well convergent, it is convenient to use for solving a domain integral equation. The mixed spatial and spectral nature of the Gabor frame creates a natural and fast way to Fourier transform a function. In the spectral domain we employ a coordinate scaling to smoothen the branchcut found in the Green function. We have developed algorithms to perform multiplication and convolution efficiently, scaling as O(NlogN) on the number of Gabor coefficients, yielding an overall algorithm that also scales as O(NlogN).

A miniaturized microstrip rat-race coupler with harmonics suppression is proposed by using shorted trans-directional (TRD) coupled lines. The shorted TRD coupled lines consist of a set of capacitor-loaded λ/4 coupled microstrip lines with two shorts, which are used to replace the 3λ/4 uniform transmission-line section (UTLS) in the traditional 3λ/2 ring coupler for miniaturization. To attain perfect matching for any coupling factor of the TRD coupled lines, shorted TRD coupled lines are synthesized and the design equations are derived. To further reduce the ring size, T-type transmission-line equivalent circuits are also adopted to replace the λ/4 UTLS and associated with a transmission zero for harmonic attenuation. Using the proposed method, a microstrip ring coupler with 26.7% circuit size of a traditional one is fabricated and tested. The measured results show that the bandwidth for the return loss of better than 10 dB is 43.9% and that for isolation of better than 20 dB is 18.7% with a maximum isolation of 40.6 dB. There is no spurious passband up to the sixth harmonic of the design center frequency with more than 20 dB suppression from the third to fifth harmonics.

In this article, a dual-polarized hybrid cylindrical dielectric resonator antenna (CDRA) is studied. A ring-shaped patch along with an inverted L-strip is used to excite two different hybrid modes (HE_11δ and HE_12δ-like mode) in CDRA. HE_12δ mode in CDRA is very advantageous in terms of gain and radiation characteristics. The proposed antenna design shows triple-band characteristics i.e. 1.88-2.06 GHz, 2.29-2.58 GHz and 2.9-3.93 GHz with the fractional bandwidth of 9.13%, 11.9% and 30.16%, respectively. Due to inverted L-strip, it shows circular polarization characteristics within the frequency range 3.3-3.55 GHz (AR<3 dB). The simulated results are practically verified by using archetype of proposed antenna structure. The proposed antenna design is applicable to WLAN (2.4 GHz) and WiMAX (2.5/3.5 GHz) applications.

Based on the theory of ionospheric heating, with the self-consistent model in the low ionosphere, the Extremely-Low-Frequency (ELF) and Very-Low-Frequency (VLF) waves generated by modulated beat-wave ionospheric heating are analyzed theoretically. In the consideration of the stratified ionosphere, the magnetic fields generated by the equivalent ELF/VLF dipole source above thesea surfaceare studied by using the quasi-longitudinal approximation method.Taking the high latitude regions as an example, the variations of the electron temperature, the increments of Pedersen and Hall conductivities and the changing of the oscillating current densitywith the modulation frequency in beat-wave heating are numerically discussed. The distribution of the magnetic fields ispresented. It turns out that in high latitude regions, the efficiency of rectangular wave modulated heating ingenerating ELF/VLF wave is higher than that of modulated beat-wave heating, and the order of magnitude of the magnetic fields received above the sea surface is 10^-7 in beat-wave modulation.

In this paper, a compact wideband planar balun is studied and investigated. The proposed balun comprises a broadband Wilkinson divider followed by non-coupled lines to attain wideband 180° phase shift. Due to the inherent broadband characteristics of the proposed structure, good performance is accomplished in terms of phase and amplitude balance. The balun is optimally designed and validated by experiments. Both measured and computed results have shown a return loss better than -10 dB, an insertion loss around of -3.15 dB with a maximum absolute phase and amplitude imbalance around 2.5° and 0.2 dB over frequency range from 700 to 3200 MHz. Practical and computed results of the present balun are in good agreement.

This paper presents a novel compact Koch snowflake fractal ring based Dielectric Resonator Antenna (DRA) for ultra wideband application. Firstly, Koch snowflake fractal geometry is implemented on the conventional Cylindrical Dielectric Resonator Antenna (CDRA). Further, the performance of the DRA is enhanced by fractal ring created on the snowflake geometry. With the application of the fractal and the fractal ring geometry, the Q-factor of DRA is reduced, thus the bandwidth of DRA is increased. The proposed antenna offers a wide impedance bandwidth of 90% ranging from 4.7 GHz-12.4 GHz. The effect of the fractal geometry enhances the gain of DRA. The proposed antenna achieves radiation efficiency more than 78%, throughout the bandwidth. Interestingly, the proposed configuration reduces the DRA volume by 76.63% with reduced volume of 7.91 cm³. The experimental verification of the proposed structure shows good agreement between simulated and measured results.

We present a revised Cauchy method to accurately extract the high quality factor of dielectric resonators from measurements. Since the losses displace all the zeros and poles of the transfer function horizontally to the left in the complex plane, the accurate evaluation of the unloaded quality factor of microwave resonators can be achieved based on the complex frequency transformation. The results show that if the three-point method is employed, the accuracy of the quality factor values deteriorates when the input/output coupling is strong. Nevertheless, a nearly constant factor value can be obtained by our proposed technique whether the input/output couplings are weak or strong. This algorithm provides an alternative method to measure the unloaded quality factor when the signal-to-noise ratio is high.

A novel CPW-fed dual-band multiple-input multiple-output (MIMO) antenna with a common radiating element for WiMax/3.5G and WLAN/5.8G is proposed in this paper. The proposed MIMO antenna which has dimensions of 30 mm×30 mm×1.6 mm consists of an irregular ring-shaped ground plane and a shared radiating element. Furthermore, this MIMO antenna has a good performance in the port isolation by using a T-shaped structure and four slots on the ground. The measured bandwidths of the designed MIMO antenna are 3.32-3.74 GHz and 5.45-6.05 GHz. In the meantime, the measured isolation of the MIMO antenna is higher than 20 dB in both bands.

Electromagnetic field modal expansion is traditionally an effective technique for solving Maxwell's Equations for numerous high-frequency engineering problems. In this paper, an alternative form of electromagnetic field representation is described. It is based on the Riemann-Silberstein vectors, which are a linear combination of the electric and magnetic field vectors. Utilizing such combination in homogeneous space, Maxwell's Equations are converted into a system of two independent equations. Under these circumstances, each vector describes the total electromagnetic field of an ideal circular polarization. Electromagnetic fields are simply expressed in the form of the Riemann-Silberstein vectors using the helical coordinate system and special functions, which form a set of generalized spherical harmonics. The new representation of vector spherical harmonics differs in simplicity and symmetry while having a more physically apparent expression. The amount of computational work is reduced due to the initial independence of the Riemann-Silberstein vectors. The purpose of this paper is to show the efficiency of a new approach that is based on Riemann-Silberstein vector field representation and spherical wave expansion.

Making use of mode matching method, a theoretical analysis of a metamaterial layer is presented. The unit cell of the structure is modeled by a TEM waveguide, and the metamaterial element is supposed as a discontinuity in the waveguide. Analyzing the structure using this model, mathematical relations between s-parameters of a metasurface are extracted. It is evident that the variation of each s-parameter is limited to an arc of circle on Smith chart. The key factors determining the location of each circle on plane are specified. Moreover, a discussion on the role of metasurface element in the determination of s-parameters of the structure is given. The variations of scattering transfer parameters on the plane are determined, too. The steps needed to derive these relations are described. Using these relations, simple and straightforward formulas are devised which can be used to predict the response of the metasurface. Finally, some metasurfaces will be analyzed by full-wave method. The new relations are well-agreed with simulation results.

This paper proposes a hybrid method to accelerate the calculation of the monostatic radar cross section (RCS) of perfect electric conducting (PEC) targets. In a sense, the proposed method can be considered as a fast adaptive cross approximation (FACA)-based method. The FACA is firstly used to compress the excitation matrix which come from the beforehand defined incident plane waves. It decreases the time and memory on the generation of decomposition form matrices throughout the comparison with the conventional adaptive cross approximation (ACA). Furthermore, the computational complexity of solution is further reduced by using the sparsified ACA (SPACA) algorithm after dividing the target into blocks. Consequently, the proposed method turns out to be efficient and accurate for calculating two-dimensional (2D) monostatic RCS.

Micro Rain Radar (MRR) is a vertical pointing microwave profiler to measure hydrometeors and related parameters in high resolution. However, it is known that the MRR suffers from certain limitations due to several factors. This paper evaluates the performance of the MRR installed at Kototabang, west Sumatra, Indonesia (0.20˚S, 100.32˚E, 864 m above sea level). The DSD and rainfall rate from the MRR standard processing method had been evaluated by using collocated measurements of MRR, Parsivel disdrometer and Optical Rain Gauge (ORG) during 2014. Furthermore, 1.3 GHz wind profiler (BLR) observation was used to examine the vertical profiles of radar reflectivity and Doppler velocity. It was found that there were noticeable differences between the MRR and Parsivel in the small and large size ends of the DSD. At small sized drop (< 1 mm), the DSD spectra of MRR was higher than that obtained by the Parsivel otherwise it was smaller for large sized drop (> 2 mm). Underestimation of large sized drops in the MRR could be responsible for the underestimation of surface rainfall rate and daily rainfall. The source of differences in the DSD seems the measurement shortcomings such as attenuation correction and vertical wind effects, particularly during heavy rain. The shortcomings were observed from the comparison of mean Doppler velocity profiles between the MRR and the BLR. While the melting layer height of the two instruments was the same, the mean Doppler velocities of MRR shown downward increasing (DI) pattern through all rainfall intensities. On the other hand, for the BLR, the DI was only observed for heavy rain (> 10 mm/h), while downward decreasing was observed for light rain (< 5 mm/h). Similar pattern was also observed for the vertical profile of radar reflectivity. Thus, some corrections are needed for heavy rain, nevertheless, the MRR installed at Kototabang can be utilized for light rain. Comparisons indicated that the mean Doppler velocity and the DSD for the light rain as well as Z-R relation were in reasonable agreement with the reference of BLR, Parsivel and previous studies using the MRR.

A novel approach to design Tunable Dual Band Band-Stop filters will be presented in this paper. These filters have a new configuration which have a coplanar microstrip line loaded with Stepped-Impedance Resonators (SIRs). These can be tuned by using tuning elements such as a tuning diode and ferroelectric capacitor. The Dual-Band Band-Stop Filter (DBBSF) and Band-Pass Filter (DBBPF) have become the most attractive circuit components in modern communication devices. Several studies have been done in this area but without tuning. Tuning is important in these circuits because the same circuit could be used in multiple band frequencies by applying a voltage, without needing to design new circuits. Thus, this approach leads the circuits to become smaller, increases the efficiency of the circuits, and reduces the costs. The filters were designed with notch frequencies at 1.5 GHz and 3.5 GHz, and then loaded respectively with Tuning Diode or BST capacitors, to compare their performance. The filter circuits were simulated with an Agilent ADS and Matlab program and were fabricated on FR-4 substrates. By loading the resonators with BST capacitors or tuning diodes, with no DC applied voltage, the first and second notch frequency shifts significantly. The application of DC bias to these varactors changes the center frequencies of the dual band filter.

In this paper a pattern synthesis method based on Differential Evolution Algorithm (DE) is presented to generate dual beam patterns from a planar array of isotropic antennas. These are cosec² pattern and pencil beam pattern. These patterns are obtained by finding out an optimum set of common elements amplitude (for cosec² pattern as well as a pencil beam pattern), and a set of phases, for cosec² pattern only. 4-bit discrete amplitudes and 5-bit discrete phases are used to reduce the design complexity of feed network. The beam patterns have been generated in two different azimuth planes instead of one particular plane. The evaluated excitations are also verified by considering a range of arbitrarily chosen azimuth planes, where the patterns are generated with some minor variations of the desired parameters. Obtained results clearly established the effectiveness of the proposed method.

Alternating current interference from power transmission lines on nearby metallic pipelines has been a topic of research in the past years. Of particular interest is the induced voltage on metallic pipelines due to the time varying electromagnetic fields coupling from the transmission lines. Several related studies dealing with this problem have been published. Nevertheless, the issue of current phase shift variation and its effect on the voltage induced on metallic pipelines has not been fully covered yet. In view of this, we present the computation of the induced open circuit voltage on a buried metallic pipeline running in parallel with the power transmission lines in three Rand Water sites, South Africa. The computation was performed using Carson's relations and power system concepts of mutual impedances between two circuits. The variation in current phase shift was considered for six different phase conductor arrangements. The overall simulation results yield useful information. The computations show that the induced open circuit voltage changes significantly with different phase arrangements and with variations in the current phase shift between the two circuits. In this work, the characteristic nature of the variation in the induced open circuit voltage for the six phase arrangements and phase shifts are examined in more detail. We concluded that in placing buried pipelines in the vicinity of AC double-circuits power lines, it is essential to consider the phase arrangement of the line and current phase shift between the two circuits. These, together with other line parameters, are vital in evaluating the induced voltage with the pipe position before installation and for the design of effective AC mitigation techniques.

Using Daubechies wavelet with one, two, three, and four vanishing moments, basis functions for the efficient solution of electromagnetic integral equations are studied. Due to the vanishing moments, the moment matrices resulting in these problems are sparsified by wavelet, and consequently, the solution can be obtained rapidly. The microstrip line is examined in order to demonstrate the advantages of this suggested wavelet-moments method over the traditional moment method. To demonstrate the effectiveness and accuracy of the proposed technique, numerical results for error relative for different vanishing moments of Daubechies wavelets are presented. It is found that Daubechies wavelets with larger number of vanishing moments generally give higher accuracy.

A new design has been proposed for a single layer polarization-insensitive dual-band metamaterial absorber at C and X bands. The proposed structure consists of a periodic arrangement of a circular resonator embedded in a square resonator. A commercially available FR4 dielectric has been used as a substrate with metallic grounded bottom and imprints on the other side. This structure resonates at 5.5 GHz and 8.9 GHz with absorptivity of 99.8% and 99.97%, respectively. It exhibits polarization-insensitive behaviour for Transverse Electric and Transverse Magnetic polarization under oblique and normal angles of incidence. The field distributions have been studied for better understanding of the absorption mechanism. The fabricated structure has been tested, and the experimental results are similar to the simulated ones. This polarization-insensitive metamaterial absorber with its ease of design and nearly unity absorption can be used for radar applications.

Permanent-magnet synchronous motors (PMSM) used for HEV/EV drivetrain have many non-linear characteristics including saturation, slotting effects and non-sinusoidal back-emf. However, accurate torque control and rigorous on-board-diagnose require precise modelling that goes far beyond capacity of conventional Space Vector based PMSM model considering only fundamental frequency. By considering the higher harmonics of PMSM, this paper introduces a novel PMSM model named Generalized Space Vector Model (GSVM) based on Fourier series reconstruction of magnetic coenergy. Firstly, two-dimensional Fourier series supplemented by polynomial fitting is introduced to reconstruct the numerical solution of coenergy from Finite Element Analysis (FEA). Secondly, analytical models of flux linkage, electric torque and voltage equation in stator current oriented synchronous frame are derived based on the reconstructed coenergy model. Finally, the steady and dynamic characteristics of GSVM are validated against experimental results.

The use of conformal antennas in a MIMO link scenario is investigated. Conformal slot antennas are considered both in the transmitter and the receiver. First, a new modified correlation coefficient is derived that goes beyond the Clarke coefficient and takes into account the element radiation pattern. Secondly, a hybrid formulation that accounts for the impact of the mutual coupling and the pattern dependent correlation on the capacity is presented. The mutual coupling for slots placed circumferentially on a paraboloid substrate is derived using a rigorous approach based on Uniform Theory of Diffraction (UTD). The capacity is evaluated for the case of Rayleigh fading channel considering the new pattern dependent correlation coefficient and the conformal antenna mutual coupling. The planar case is included as a limiting case. It is shown that for conformal antennas on a paraboloid the capacity degradation compared to the planar case is up to 0.5 bps/Hz due to coupling and correlation.