A rigorous fast numerical method called E-PILE+SMCG is introduced and then used in a Monte Carlo study of scattering from a three dimensional perfectly electrical conductor (PEC) object below lossy soil rough surface. This method is the three dimensional (3D) extendability of PILE (Propagation-Inside-Layer Expansion) method which is proposed for two dimensional (2D) scattering problem. The rough surface with Gaussian profile is used to emulate the realistic situation of statistically rough surface, while the tapered incident wave is chosen to reduce the truncation error. The 3D angular correlation function (ACF) and bistatic scattering coefficient (BSC) are studied and applied to the detection of a target embedded in the clutter. The ACF is computed by using numerical method with circular azimuthal angle averaging technique. Because of its success in suppressing the clutter scattering, the technique appears attractive in real life implementation.

A numerical solution for the dipole antenna with a bi-isotropic object in the vicinity is developed. This solution is based on the combined surface integral equation which could deal with homogeneous situation. A fields splitting scheme is deployed to circumvent the difficulties caused by the complexity of constitutive relationships of bi-isotropic materials. With the aids of MoM, a FORTRAN program can be developed. At the end of this paper, some numerical results are presented.

In this paper, a novel dumbbell shaped slot resonator (DSSR) is introduced and investigated based on a circuit theory and electromagnetic (EM) simulation. Lumped and distributed equivalent circuit models are then presented for an analysis of the proposed DSSR. The circuit and EM simulated results validate the DSSR's equivalent circuit models and their analysis methodologies. Since the proposed DSSR does not employ ground slots, additional etching process for the ground plane is not necessary. Thus, one can minimize the cost and fabrication errors. For the DSSR's applications, the miniaturized tunable DSSR and band-pass filter (BPF) are designed, simulated, and measured. The tunable DSSR does not require additional lumped DC-block capacitors since DC is isolated due to the coupled gap structures in an input and output. In the BPF design, two DSSRs are simply coupled by input/output ports. Both simulated and measured results of the designed tunable resonator and BPF show good agreement.

Magnetic refrigeration is an innovative, revolutionary, efficient and environmentally friendly cooling technology which is on the threshold of commercialization. The essential components of magnetic refrigeration system are the magnetic field generator and the magnetocaloric material. The two main goals of this paper are to design and to optimize a permanent magnet magnetic refrigeration machine for power cooling generation, where an initial configuration is studied and based on this study two other configurations are presented. Both electromagnetic and thermal studies are explored. The electromagnetic design part has been accomplished by using the finite elements method and the thermal design part has been achieved using the finite difference method. ⁵⁷

The aim of this paper is to validate a proposed simplified boundary-integral approach (that is called here LEM&BEM) for the analysis of electric field in a live-line-working zone. A human body model of a simplified geometry that is applied to the electric field estimation around the live-line worker is also tested. Numerical results of a more accurate numerical approach, laboratory measurements as well as results of measurements taken on a real tower of HV overhead line are employed for this purpose. The numerical analysis of the electric field distribution in the hot-stick working zone on an anchor tower of 400 kV transmission line is presented to demonstrate the effectiveness of the numerical technique under consideration. The author's own software packages has been applied in computations.

Actually MEMS technology allows to fabricate free standing and bended cantilevers by acting on stress/strain properties and thicknesses of materials. In particular, by means of MEMS technology it is possible to realize ring or spiral layouts with piezoelectric materials. The mechanical movement due to the piezoelectric resonance can be used in order to modulate a signal travelling in the MEMS and radiating in the free space as happens in antennas. In this work we provide an accurate study regarding the design approach of piezoelectric aluminium nitride (AlN) ring antenna. The study is developed by means of a tailored 3D FEM tool which allows to analyze the piezoelectric resonances and to design the ring micro-antenna in the THz range. Finally we provide the technology and we measure the piezoelectric resonances of ring antennas.

Several studies have investigated the possibility of using the Radar Target Signature (RTS) of a tumour to classify the tumour as either benign or malignant, since the RTS has been shown to be influenced by the size, shape and surface texture of tumours. The Evolved-Topology Spiking Neural Neural (SNN) presented here extends the use of evolutionary algorithms to determine an optimal number of neurons and interneuron connections, forming a robust and accurate Ultra Wideband Radar (UWB) breast cancer classifier. The classifier is examined using dielectrically realistic numerical breast models, and the performance of the classifier is compared to an existing Fixed-Topology SNN cancer classifier.

This article presents a compact dual band-notched UWB antenna with a pair of L-shaped and modified L-shaped slots on either side of the ground plane for the 3.5/5.5 GHz dual band-notched characteristics. The radiating patch of the proposed antenna has a ladderlike structure symmetrically and fed by a 50-Ω microstrip transmission line. By etching two sets of L-shaped slots on the ground plane, dual band-notched properties in the WiMAX/WLAN bands are achieved, respectively. The proposed antenna has the promising performance including matched impedance, consistent radiation pattern and stable gain.

This paper reports design and development of an innovative compact Stepped Truncated-Circular Waveguide Branching Ortho-Mode Transducer (STCWB-OMT) operating at 4.5-4.8 GHz for horizontal and vertical polarizations. STCWB-OMT is derived by introducing branch waveguide via coupling slot on a stepped truncated-circular waveguide. This configuration possesses inbuilt rectangular-to-circular transition; therefore it does not require any additional square-to-circular transition to combine it with horn antenna. The challenge in the design incorporated is to obtain a mechanically compact design with low mass while compliant with the specified electrical performances; since this device is developed for space-borne application. Achieved return losses at both direct and coupled ports are >17 dB, insertion losses <0.08 dB for both polarizations, isolation is <-60 dB and cross-polarization discrimination >40 dB with the OMT length = 1.98λ atcenter frequency and weight = 250 gm The agreement between measured and computed results provides a validation of the proposed OMT configuration.

This paper is a theoretical investigation and analysis of the focal region fields of a hyperbolic focusing lens embedded in chiral medium. Chiral-dielectric and dielectric-chiral interfaces are studied and the behavior of waves after passing through these interfaces are discussed. Geometric optics (GO) is used initially. However, it fails around the focal region because it gives non-realistic singularity in this region. So, Maslov's method is used in the caustic region and the field analysis is made. The effect of chirality variation on the amplitude of the fields around the focal region is given and discussed.

A new radar cross section (RCS) prediction technique based on beam tracing is presented. The incident plane wave is modeled as a set of trigonal ray tubes, and each ray tube is traced and recursively subdivided as its reflection aspect. The calculation time of the proposed method is independent of target size. The proposed method provides accurate solutions and is efficient for RCS analysis of electrically large targets.

In this work, a nonlinear technique for the optimization of the synchronization bandwidth of Rationally Synchronized Oscillators (RSO) is presented. The circuit is forced to operate near a Hopf bifurcation point which is created around the frequency of the input reference signal. Under this operating regime, the reference signal is strongly amplified and the synchronization bandwidth of the circuit is considerably improved. A 5-3 GHz rationally synchronized oscillator has been optimized using the proposed method. The manufactured RSO provides a 5 MHz synchronization bandwidth with a reference signal power of -22 dBm, in good agreement with simulation results.

A CPW-fed UWB antenna with WiMAX and WLAN band-notched characteristics is presented in this paper. The proposed antenna is fed by a CPW structure and provides the band-notched characteristics by etching an arc slot on the monopole plate and integrating the antenna with electromagnetically coupled microstrip resonator into a single module. In order to prevent interference problem due to existing nearby communication systems within the UWB operating frequency, the two band-notches are designed to reject possible interference with the existing 3.25-3.75 GHz band for IEEES02.16 WiMAX and 5.15-5.825 GHz band for IEEES02.11a WLAN and HIPERLAN/2 WLAN The two notched bands can easily be controlled by a few geometry parameters of the arc slot and the microstrip resonator. Surface current distributions and conceptual equivalent-circuit models are used to analyze the effect of the slot and the resonator. The proposed antenna is simulated and fabricated. Moreover, the performances of the antenna are demonstrated along with simulated and measured results.

We study the rectangular tips of the dipole photoconductive antenna, which has been widely used for terahertz radiation and detection, with different blend radii effect on the emission performance of terahertz (THz) radiation. For the amplitude of THz radiation pulse is proportional to the local electric field in the gap, the increased maximum bias electric field by blending tips is able to achieve higher THz radiation power. Both considering the influence to the maximum bias electric field and the emission efficiency, the blend radius of the rectangular tips is suggest to be larger than 5 μm and the radiation power is largely enhanced. Comparing to the previous work, our method has better THz radiation performance.

Unlike some traditional polynomial phase signal (PPS) parameter estimation methods restricted to monocomponent case, this paper focuses on the parameter estimation of multicomponent PPSs mixed in a single channel, which is more sophisticated and always involves the cross-term issue. In this investigation, based on the model of multicomponent PPSs in additional white Gaussian noise, we partition the maximum likelihood estimation into two consecutive steps. The first one involving estimation of polynomial coefficients is intensively studied using importance sampling, while the second one involving the estimation of amplitude and initial phase is trivial. Numerical experiments show satisfactory estimation performance even if the parameters are closely spaced.

DeDesign procedure for a modified Composite Right/Left Handed (CRLH) unit cell is represented. The ferroelectric interdigital capacitor (IDC) is used as a tuned capacitor, and spiral inductor is utilized to implement inductors. A modified CRLH unit cell is attained by moving the shunt inductor of conventional unit cell to both ends with doubled values. In this manner, only one bias network would be required for each unit cell. The parameters of the designed unit cell are obtained so that the Bloch impedance to be equal to 50Ω and the Bloch propagation constant to have one zero at the operational frequency. The operational frequency is chosen equal to 11.45 GHz, which is in the Ku-band and in middle of the up-link satellite communications. To design the modified unit cell, initially, the unit cell without a shunt capacitor is constructed. This would result in Π-model structure for which the element dimensions are varied to reach the desired values. Next, the shunt capacitor is added to the model and its length is varied until the balanced condition is achieved.

In this paper, transmission properties of stacked split ring resonators metasurfaces in free space and under normal incidence are investigated experimentally and numerically. Emphasis is put on studying the interaction between adjacent SRRs metasurfaces. The thorough analysis of the electromagnetic fields shows that both magnetic and electric coupling can occur between adjacents metasurfaces for vertical and horizontal polarization. In addition, we found that all propagating bands within our spectral window (up to 20 GHz) support right-handed behaviour. Both simulation and experiment results in the microwave regime are in good agreement.

Antenna array beamformers suffer from performance deterioration in the presence of mutual coupling (MC) between array sensors. In this paper, we present a theoretical analysis in terms of the output signal-to-interference-plus-noise ratio (SINR) for the performance of antenna array beamformers under MC effects. Based on the model of a distortion matrix to encapsulate the MC effects, a closed-form expression for the SINR is derived that is shown to accurately predict the SINR obtained in simulations. This theoretical formula is valid for any distortion matrix estimated from collected measurement data. The SINR formulas provide insights into the influence of the MC effects on the performances of the linearly constrained minimum variance (LCMV) beamformer and the eigenspace-based (ESB) beamformer. It is shown that the ESB beamformer outperforms the LCMV beamformer under MC effects. Moreover, we derive the formulas for computing the eigenvalues of signal correlation matrix under MC effects. Simulation results are presented for confirming the validity of the theoretical results.

In this paper, a novel design of dual-band microstrip antenna with complementary split ring resonators (CSRRs) is presented. A simple and successful dual-band antenna can be realized by etching three CSRRs in the ground plane of a conventional patch antenna. The proposed antenna shows good performances at both resonant frequencies. The CSRRs embedded in the ground plane make a major contribution to the first operating band, but has minor effect on the second operating band. It is beneficial for designing a dual-band antenna as well as a miniaturized antenna flexibly. The simulation results are analyzed and compared with measured results in a good agreement.

The microwave backscattering of the sea surface is investigated with the wedge-shaped breaking waves for the super events at low grazing angles (LGA). According to the relationship between the wave breaking and the whitecap, the finite three-dimensional wedges are utilized to approximately model the breaking waves, of which the spatial distribution is simulated with whitecap coverage. The phase-modified two-scale method (TSM) and method of equivalent currents (MEC) are used to calculate the surface and volume scattering of sea surface and breaking waves respectively. The sea spikes in LGA are observed by this model, and the strong directionality is caused by the breakers. Considering the Bragg phase velocity, orbital motion of facets and wind drift, the Doppler spectrum is simulated with the time series of sea clutter. Included the breaking waves, the scattering model indicates that the enhanced non-Bragg scattering leads to the extended Doppler spectrum width. The numerical results agree with the measured data well at LGA. Compared with the statistical models, the complex physical mechanism of the sea scattering is explicitly described in this paper.