Inferring refractivity profiles from radar sea clutter is a complex nonlinear optimization problem. Previous works treat this problem as a model parameter estimation issue by using some idealized refractivity models, such as the Log linear evaporation duct model, bilinear model, and trilinear model, to describe the synoptic structure of the real atmospheric conditions. However, these idealized models can not describe the exact information of the refractivity profile. Rather than estimating a few model parameters, this paper puts forward possibilities of retrieving the refractivity values at each point over height by variational adjoint approach for RFC measurement geometry. The adjoint model is derived from the parabolic equation for a smooth, perfectly conducting surface and horizontal polarization conditions. An evaporation duct profile collected at East China Sea is provided as the true refractive environment. The performance of this approach is determined via simulations and is evaluated as a function of: 1) the initial guess profile; 2) the measurement noise; and 3) the spatial samples.

In this paper, a new kind of end-fire array was built by employing high directivity plate end-fire antenna as the basic element based on electromagnetic surface wave theory. Being different from normal end-fire array, in the new array, high directivity plate end-fire antenna elements were arranged end to end along the end-fire direction, and the interelement spacing and uniform progressive phase were carefully adjusted to achieve high directivity. The simulations and measurements showed that the whole array achieved 19.2 dB directivity with four elements at 14.7 dB directivity each.

A coplanar waveguide (CPW)-fed planar monopole antenna with triple-band operation for worldwide interoperability for microwave access (WiMAX) and wireless local area network (WLAN) applications is presented. The antenna comprises dual rectangular ring with open-end. The triple operating bands with 10-dB return-loss bandwidths of about 30.8% ranging from 2.2 to 2.97 GHz, 23.4% ranging from 3.17 to 3.99 GHz, and 25.4% ranging from 4.91 to 6.31 GHz, covering the required bandwidths of 2.4/5.2/5.8 GHz WLAN and 3.5/5.5\,GHz WiMAX standards, are obtained.

An automatic process to design a multiband filter in Non-uniform Transmission Line (NTL) form is presented. The proposed approach supports with Time Domain Reflectometry (TDR) technique instead of the traditional methods such as methods based on Inductor-Capacitor filters. The proposed method is described step-by-step and is illustrated by an example emphasizing key points. A critical analysis of this technique is done for emphasizing its limitations. For illustrating the design process, a multiband Ultra Wideband (UWB) filter rejecting two frequency bands is designed.

This work presents a light-weight microwave system for the search and rescue of victims trapped under the rubble of collapsed building during an earthquake or other disasters. The proposed system based on a continuous wave X-band radar is able to detect respiratory and heart fluctuations: the information is extracted from the backscattered electromagnetic field exploiting independent component analysis (ICA) algorithm which provides an efficient noise and clutter cleaning. The proposed rescue radar is compact enough to be mounted onboard of a small unmanned aerial vehicle (UAV) in order to reach inaccessible or dangerous areas. The obtained experimental results show that the proposed detection method is able to successfully locate trapped victims with a reasonable degree of accuracy.

A new method for tracking characteristic numbers and vectors appearing in the Characteristic Mode Theory is presented in this paper. The challenge here is that the spectral decomposition of the moment impedance-matrix doesn't always produce well ordered eigenmodes. This issue is addressed particularly to finite numerical accuracy and slight nonsymmetry of the frequency-dependent matrix. At specific frequencies, the decomposition problem might be ill-posed and non-uniquely defined as well. Hence an advanced tracking procedure has been developed to deal with noisy modes, non-continuous behavior of eigenvalues, mode swapping etc. Proposed method has been successfully implemented into our in-house Characteristic Mode software tool for the design of microstrip patch antennas and tested for some interesting examples.

A coplanar waveguide (CPW) fed ultra-wideband (UWB) antenna with a notch band characteristic is presented in the paper. The radiation patch of the proposed UWB antenna is designed using cantor set fractal technology. The bandwidth is broadened by setting two symmetrical triangular tapered corners at the bottom of the wide slot of the proposed UWB antenna. The notched band characteristic is achieved by employing a T-shaped tuning stub at the top of the wide slot. The notched band can be controlled by adjusting the length and the width of the T-shaped tuning stub to give tunable notched band function. The proposed cantor set fractal wide slot UWB antenna has been designed in details and optimized. Experimental and numerical results show that the proposed antenna, with compact size of 26×21 mm², has an impedance bandwidth range from 2.8 GHz to 11 GHz for voltage standing-wave ratio (VSWR) less than 2, except the notch band frequency 5.0 GHz-6.3 GHz for HIPERLAN/2 and IEEE 802.11a (5.1 GHz-5.9 GHz).

This work proposes a symmetrical offset stack coupled lines balun and a dual balun for a single balanced mixer and a star mixer, respectively. To achieve a minimum insertion loss and a maximum bandwidth, the design formulas are derived by properly selecting the width of coupled lines and the offset width between two coupled lines. The measured results of the proposed single and dual baluns achieve the bandwidths of over 110% and 90%, and insertion losses of less than 4.4 dB and 7.4 dB at 38 GHz. These two baluns occupied chip sizes of 0.07 mm². Two balanced diode mixers are further proposed and implemented in tsmc^TM 0.18-μm CMOS processes. These mixers utilize a stack balun feature wide bandwidth with very compact size. The measured results of the single balanced and star mixer achieve over 115% and 100% bandwidth for a conversion loss of <15 dB. The isolations are better than 24 dB from 10 to 65 GHz of the single balance mixer and better than 31 dB from 20 to 65 GHz of the star mixer.

In this paper, design of a coplanar capaciπtive coupled probe fed microstrip ring antenna for dual frequency operation is presented. The proposed antenna is excited by a single probe feed connected to a capacitive feed strip placed along one of the radiating edges of the ring antenna. The coplanar capacitive feed strip is modified to obtain the best possible match with the antenna input impedance and to tune out the excessive capacitive reactance due to feed strip. It is also demonstrated that the modified feed strip can be placed either inside or outside the ring and similar radiation characteristics can be obtained at both the resonant frequencies. Ring dimensions decide the resonant frequencies values and their separation. Measured data fairly agree with the simulated characteristics.

In the distributed small satellites synthetic aperture radar (DSS-SAR), baseline is usually coupled, that is, along-track baseline and across-track baseline exist simultaneously. However, coupling baseline makes it difficult to distinguish phase differences caused by terrain height and Doppler frequency difference. In SAR interferometry (InSAR) geometric model, across-baseline is necessary to bring interferometric phase to estimate terrain height. Oppositely, along-track baseline will bring extra phase difference and dramatically decrease the accuracy of terrain height estimation. Considering the aforementioned problem, this paper focuses on the study of baseline decoupling of DSS-SAR. We firstly analyze the effect of coupling baseline on terrain height estimation, and then propose the method of baseline decoupling through space projection theory. In order to realize baseline decoupling, equivalent slave satellite, equivalent baseline, and equivalent slant range are defined through projecting slave satellite on range-height plane of master satellite. Furthermore, based on our baseline decoupling, an advanced approach of estimating terrain height is presented, which is more effective than traditional InSAR geometric model. Simulation results illuminate that the baseline decoupling can eliminate along-track baseline effect on terrain height estimation effectively and confirm the validity and efficiency of terrain height estimation approach proposed in this paper.

This paper deals with the influence of the AC machine pole number on vibrations and noise of electromagnetic origin. First, rules of design of AC machines are reminded, pointing out the influence of the pole number. Then, the origin of magnetic vibrations and noise is explained. Analytical mechanical relations are given, allowing to estimate vibrations and noise of a machine. After that, the influence of the pole number is studied: on the machine radius, on the stator deformations, on the mechanical resonance frequencies and on the noise. The conclusions underline that machines with high pole number have stator vibrations of high amplitude. Calculations compare three machines with different pole number and fed at different frequencies. The conclusion is that, at the same speed and working power, machines with high pole number fed at high frequency are noisier than those with low number of poles fed at low frequency. Practical experiments illustrate these theoretical considerations.

It is proven that for the damped wave equation when the Laplace transforms of boundary value functions ψ(0,t) and (∂ψ(z,t)/∂z)_z=0 of the solution ψ(z,t) have no essential singularities and no branch points, the solution can be constructed with relative ease. In such a case while computing the inverse Laplace transform, the integrals along the segments on the real line are shown to always cancel. The integrals along the circles C_^→ε and C'_^-ε about the point s=-σ/ε determined by the coefficient of the time derivative in the differential equation and point s=0 are shown to vanish unless Laplace transforms of mentioned boundary value functions have poles at these points. If such poles do exist, the problem is nevertheless one of integration along circles about these poles and then setting the radii of these circles equal to zero in the limit.

The paper discusses the reason why the image resolution can be significantly enhanced by the superlens with anti-reflection and phase control coatings (ARPC-superlens) via analyzing the surface plasmons (SPs) modes. ARPC-superlens is an asymmetric structure with finite thickness, in which we first find that there are two asymmetric SPs modes. By comparing the dispersion curve of SPs of ARPC-superlens and the SPs group velocity with their counterparts in the metric ones, we find that the Up Asymmetric Mode and Down Asymmetric Mode are excited within the ARPC-superlens with asymmetric structure. By simulating the aerial images in different SPs modes, the paper also discusses the optimal ratio between the metal slab and the ARPC coatings thickness. The results demonstrate that the subwavelength resolution of ARPC-superlens in Down Asymmetric Mode has been enhanced, when the metal/ARPC thickness ratio is 2:1.

This paper demonstrates a novel and superior approach to enhance the incident angle based spectrum tuning capability of 1D ternary Photonic Band Gap (PBG) structure. The incidence angle sensitive wavelength band shift of a ternary periodic structure was significantly enhanced when the refractive index of sandwiched layers in each period was changed to 1.5 from 2.04. The ranges of enhancements for TE and TM wavelength band shifts were 0.5-1.5 nm and 5.5-20.5 nm respectively at different angles of incidence of light on the structure. Unlike previous approach, this approach not only enhances the incidence angle based spectrum tuning capability of 1D ternary PBG structure, but, it also ensures that the size of structure does not increase and temperature immunity of the structure does not decrease to enhance spectrum tuning capability.

A general rigorous analytic framework for computing the transmembrane potential shift resulting from the nonlinear voltage-current membrane relationship in response to wideband stochastic electromagnetic radiation is outlined, based on Volterra functional series. The special case of an insulated cylindrical cell with Hodgkin-Huxley membrane in an infinite homogeneous medium is worked out in detail, for the simplest case where the applied electric is normal to the cell axis, and independent from the axial coordinate. Representative computational results for a zero-average stationary band-limited white Gaussian incident field are illustrated and briefly discussed.

The purpose of this paper is to propose a novel generalized single-band transformer for two arbitrary complex load and source impedances and a novel high-power amplifier using this new transformer. By adding two reactive parts at across terminals, the coupled line with flexible electrical length has practical even- and odd-mode characteristic impedances. Thus, the total circuit layout can be realized on common printed circuit board without any restriction. The synthesis theory of this proposed transformer is complete and analytical. Furthermore, unlike conventional quarter-wavelength transformers, this structure exhibits four main features such as effective matching for extremely low-resistive load impedance, effective matching for extremely high-resistive load impedance, tunable characteristic for equivalent electrical length and inherent DC-block function. For theoretical verification, several impedance transformers, which include some fixed operating-frequency cases and a tunable case, for smaller than 7 Ohm or larger than 1500 Ohm, are presented. As a typical experimental example, this analyzed transformer with inherent DC-block function has been applied in a 4-Watt power amplifier as output matching structure.

This paper presents an improved polar format algorithm (PFA) for geosynchronous synthetic aperture radar which undergoes a near-circular track (GeoCSAR). GeoCSAR imaging geometry and signal formulation considering orbit perturbations were derived to ensure accurate slant range between antenna and targets. The illuminated area is more than one million square kilometers due to the long slant distance, resulting in large amount of data to be processed and that the scene is a spherical crown rather than a plane. By assuming spherical wavefronts instead of planar wavefronts, improved polar format algorithm (PFA) was proposed to focus GeoCSAR raw data on a spherical reference surface (ground surface), so that the size of focused scene is no longer limited by the range curvature phase error. Thus, this method could deal with large area imaging for GeoCSAR precisely and efficiently. The implementation procedure, computational complexity, phase error and achievable resolution were presented to show the focusing capabilities of this imaging algorithm. Numerical simulation was further performed to validate the feasibility of this imaging algorithm and the correctness of analysis.

Monte Carlo scalar radiative transfer simulation of light scattering in plane parallel slab is not a simple problem, especially in the study of angular distribution of light intensity. Approximate phase function such as Henyey-Greenstein is often used to simulate the Mie phase function. But even for sphere particle this function is sometimes a poor approximation of real phase function. For a spheroids particle, the angular scattering characteristics cannot be approximated as H-G phase function with sufficient accuracy. In this paper, we study the transmission characteristics of light in parallel plane layer with randomly oriented prolate spheroids aerosol particles. Instead of using H-G phase function, we use sampling method to simulate real phase function of spheroid directly. A database of phase function with various scattering angle and azimuth angles for given spheroids aerosol particle is developed. The transmission characteristics calculated by scattering phase function sampling method and equivalent volume sphere H-G phase function method are compared. The effect of prolate spheroids particle size and form factor on optical transmission properties is analyzed. It is found that although the construction database of phase function takes a certain amount of computing time, for spheroid particles the sample phase function method, compared with the H-G phase function simulation method, can greatly improve the accuracy of transmittance calculation.

In this paper, we present numerical simulations and indoor bistatic scattering measurements on scaled targets. The targets are vertical and/or tilted dielectric parallelepipeds representing the main forest elements (tree-trunks and primary branches) at VHF and low-UHF frequencies. They are placed above an aluminum circular plate to simulate a flat ground. The measurements have been conducted in the anechoic chamber of the ``Centre Commun de Ressources Micro-ondes'' (CCRM) in Marseille, France. A 3D forest scattering model using a Method of Moments (MoM) is deployed to simulate the electric fields scattered by these targets. Two radar geometric, azimuthal and zenithal, bistatic configurations with special attention to the specular direction have been considered. Simulation results and experimental data are confronted for both {VV-} and {HH-}polarizations in order to evaluate the accuracy of our model. We have obtained a very good agreement between theoretical and experimental scattered fields for both the magnitude and phase.

The preliminary design concept, for a low-loss, high-bandwidth electromagnetically coupled vertical transition for use as a via between adjacent levels of a 3D-MCM based on membrane-supported striplines with micro-machined shielding, is presented. The design methodology, modeling using Ansoft HFSS and simulated results are presented and together represent a complete electrical characterization of the vertical transition. The simulated insertion loss of these structures is shown to be as low as 0.12 dB at 60 GHz with a 44 GHz 1 dB bandwidth. Besides studying the vertical transition, the analysis is extended to identify the range of directional coupling which can be achieved using this type of structure, which is shown to be greater than 3 dB. The structures studied rely on a versatile micromachining technique for the fabrication of the micro-shielding which allows for the conformal packaging of lines and devices, with the ultimate aim of realizing 3D system-in-a-package type modules. The concept and proposed fabrication techniques for these modules, including methods of flip-chip MMIC attachment are detailed.