Electromagnetic field simulation of target detection by high-resolution radar

The asymptotic waveform evaluation (AWE) technique is utilized to deal with broadband electromagnetic problems of surface–wire junction geometries in this paper. To ensure the current continuity, triangles-to-segments junction model is used and the Rao–Wilton–Glisson (RWG) and triangular basis functions are used to solve the distributions of current on perfect electric conductor and wire, respectively. Then, the current on surface conductor, wire, and junctions are expanded in a rational function via Padé approximation. The AWE technique needs to store the high-order derivatives of the self-impedance and mutual-impedance matrices of surface–wire, which increase the memory requirements. Thus, the adaptive integral method is employed to reduce memory requirements and to accelerate the matrix-vector multiplications in an iterative solver. Finally, some numerical examples are shown to demonstrate the efficiency and accuracy of the proposed method

An optimal pole selection process is introduced to deal with the problem of the sensitivity of the asymptotic waveform evaluation (AWE) technique to output choice. A selection criterion is developed which provides a measure of the relative accuracy of an approximating set of poles and residues. Subsequently, an algorithm in which several sets of approximating poles and residues are generated and an optimal set is chosen based on the derived selection criterion is introduced. The algorithm results in visibly improved accuracy in both transient and frequency analysis as compared to the conventional AWE method. Several examples are presented which demonstrate the accuracy of the proposed technique as compared to previously published methods. >

An efficient algorithm is presented to quickly evaluate the frequency-domain response of a patch antenna. The method is based on the combination of the higher order vector finite element method (FEM) and the asymptotic waveform evaluation (AWE) technique for efficiently computing the frequency-domain response. The effect of moments in the power series is discussed. Numerical results for input impedance given below show that the algorithm can achieve very good approximations in the desired frequency band.

The Tickhonov based well condition asymptotic waveform evaluation (TWCAWE) is presented here to study the non-Fourier heat conduction problems with various boundary conditions. In this paper, a novel TWCAWE method is proposed to overwhelm ill-conditioning of the asymptotic waveform evaluation (AWE) technique for thermal analysis and also presented for time-reliant problems. The TWCAWE method is capable to evade the instability of AWE and also efficaciously approximates the initial high frequency and delay similar as well-established numerical method, such as Runge-Kutta (R-K). Furthermore, TWCAWE method is found 1.2 times faster than the AWE and also 4 times faster than the traditional R-K method.

In this paper, radar absorbing material (RAM) is utilized to reduce the scattered field of metal beams in all directions. Equivalence principle is used to divide the primal question into two, and then the electric field and magnetic field integral equation can be built according to boundary condition. When the equivalent electric current and magnetic current on outer surface are obtained by moments method, the scattered field and bistatic scattering cross section can be predicted in a single frequency. The forward scattering cross section over a frequency band can be simulated by using moments method in conjunction with asymptotic waveform evaluation (AWE) technique. The numerical result agrees with the result simulated by CST very well, hence the correctness of the methods adopted in this paper.

An improved eigenmode expansion method (EEM) is proposed for analyzing power/ground plane pairs in high-speed printed circuit boards (PCB). We notice that the EEM is only applicable for regular structures in a PCB, such as rectangular and circular geometries, and it costs much computational time. Therefore, asymptotic waveform evaluation (AWE) technique and inverted composition method are combined with the EEM for capturing frequency-dependent transfer and self impedances of the power/ground plane with single or even many holes. The simulation results show that good agreements are achieved between our results and those obtained by finite-element method (FEM).

Two widely used algorithms in computational electromagnetics (CEM) society, namely the asymptotic waveform evaluation (AWE) technique and the model order reduction (MOR) mode matching method, are employed to calculate electron wave propagation in novel nanoelectronic devices.

An efficient wide-band analysis that combines method of moments-physical optics (MoM-PO) hybrid formulation with the asymptotic waveform evaluation (AWE) technique is presented for antennas around an electrically large platform. To facilitate the analysis of large problems, compared with MoM, the MoM-PO hybrid formulation is employed to reduce the number of unknowns and memory requirements. Further, the automatic differentiation (AD) approach is used to calculate the high order frequency derivatives of Green's functions required in the algorithm. Numerical results show the efficiency and capability of the method proposed in this paper.

This paper describes a new approach to spectral response computations of an arbitrary two-dimensional (2-D) waveguide. This technique is based on the tangential-vector finite-element method (TVFEM) in conjunction with the asymptotic waveform evaluation (AWE) technique. The former is used to obtain modes characteristics for a central frequency, whereas the latter employs an efficient algorithm to compute frequency moments for each mode. These moments are then matched via Pade approximation to a reduced-order rational polynomial, which can be used to interpolate each mode over a frequency band with a high degree of accuracy. Furthermore, the moments computations and subsequent interpolation for a given set of frequency points can be done much more rapidly than just simple simulations for each frequency point.

A method is described for the transient analysis of lossy coupled transmission line networks with nonlinear elements. The method combines the asymptotic waveform evaluation technique with a piecewise decomposition algorithm. Two to three orders of magnitude speedup can be achieved relative to previously published methods with comparable accuracy. The method is useful for delay and crosstalk simulation of high speed VLSI interconnects.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The method of moments (MOM) in conjugation with the best uniform rational approximation is applied to predict the broad-band radar cross-section of arbitrarily shaped three-dimensional (3D) bodies. The surface integral equations are solved using MOM to obtain the equivalent surface currents at the frequency points corresponding to the Chebyshev nodes, and then the surface current within the given frequency band is represented by the Chebyshev series. To improve the accuracy, the Chebyshev series is matched via the Maehly approximation to a rational function, which can be as good as the best uniform rational approximation. Using the rational function, the surface current is obtained at any frequency point within the frequency band. Numerical results for 3D arbitrarily shaped perfectly electric conducting objects and homogenous dielectric bodies are considered. Compared with the asymptotic waveform evaluation technique and the model-based parameter estimation, the proposed technique is accurate in much broader frequency band with lower memory required.

The general asymptotic waveform evaluation (GAWE) is proposed for computing the radar cross section (RCS) of an arbitrarily shaped three-dimensional perfect electric conductor (PEC). In the novel technique, the solution of a matrix equation is approximated by the fraction expression with a numerator of vector summation and a denominator of vector summation. The comparison of the GAWE and the traditional asymptotic waveform evaluation (AWE) is also given. Finally, the RCS for different PEC objects such as a square plate, an angular-plate and a cube are computed. The results prove that the extrapolation frequency range in GAWE is wider than that in AWE under the same order derivative. Meanwhile, the computed speed in GAWE is hardly different with that in AWE.

Nonuniform transmission lines are encountered in high-speed VLSI circuits due to complex interconnect geometries and nonuniform electromagnetic coupling. Analysis of arbitrary nonuniform coupling advocates the need for a general and efficient numerical technique. This paper presents the analysis of coupled multiconductor lossy nonuniform transmission lines, using the highly efficient Asymptotic Waveform Evaluation technique.

The reliable and efficient design of monolithic millimetre-wave integrated circuits (MMICs) mandates accurate transistor models. With increasing frequency the dimensions of the transistor feeding network can not be neglected and an impedance transformation within the feeding network occurs. MMIC designers demand for versatile and scalable transistor models. This makes a precise knowledge of the transistor feeding structures and their separation from the intrinsic transistor necessary. Electro-magnetic (EM) field simulations are carried out and based on these, the scalable transistor feeding structure is extracted as a lumped circuit network. In this paper we demonstrate the modelling and parameter extraction of a metamorphic high electron mobility transistor (mHEMT) in common-gate (CG) configuration up to 325 GHz. A step-by-step description of the procedure is given, followed by a measurement-based verification of the approach up to 110 GHz.

In this paper we describe a CAD environment for performance and yield driven circuit design with electromagnetic (EM) field simulations employed within the optimization loop. Microstrip structures are accurately simulated and their responses are incorporated into the overall circuit analysis. We unify the component level interpolation technique, devised to handle discretization of geometrical parameters, and the modeling technique used to lighten the computational burden of statistical design centering. We discuss the organization and utilization of the data base system integrated with the modeling technique. We demonstrate the feasibility and benefits of performance and yield optimization with EM simulations.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>