摘要:

AbstractThis article illustrates how the bandwidth of a high‐transimpedance optoelectronic integrated circuit amplifier, involving a metal‐semiconductor‐metal (MSM) photodiode and heterojunction bipolar transistors (HBTs), can be improved by incorporating the concept of emitter RC‐network shunt peaking often used in common‐emitter voltage amplifiers. In the IC amplifier considered, the bandwidth has been shown to increase, with shunt peaking from 17.2 to 24 GHz, with no change of the equivalent input noise current (=2.3 pA/√Hz), arising mainly due to the input transistor's base current and the feedback resistor. © 1994 John Wil

ISSN:0895-2477    

DOI:10.1002/mop.4650070602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractA high‐frequency solution is developed for the electromagnetic diffraction of an obliquely incident plane wave by a material‐coated perfectly conducting half‐plane. It is assumed that the coating is electrically thin so that it can be modeled by a generalized impedance boundary condition of O(t), where t is the coating's thickness. © 1994 John Wiley&Son

ISSN:0895-2477    

DOI:10.1002/mop.4650070603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe recent application of wavelet transforms in method‐of‐moments solutions for scattering problems is extended to cases involving metallic cylinders whose periphery contain a variety of length scale features ranging from smoothly varying large‐scale features to rapidly varying small‐scale ones. The basic idea is to first consider a periodic extension of the equivalent current in the arc‐length variable with a period identical to the scatterer circumference, and then to expand this representation, using a set of periodic wavelets derived from a conventional basis of wavelets by a periodic extension. Using a Galerkin method and subsequently applying a threshold procedure, a substantial reduction in the number of elements of the moment‐method matrix is attained without virtually affecting the solution accuracy. The proposed extension is illustrated by a numerical study of TM (transverse magnetic) scattering from a cylinder of elliptic cross section. © 1994 John Wil

ISSN:0895-2477    

DOI:10.1002/mop.4650070604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractA numerical approach for the evaluation of the double integrals that arise in the analysis of printed circuit antennas is developed. In this method, the integration variables in the integrals are transferred to the polar coordinate system (λ, θ). The approach focuses on the fact that the oscillating frequency of the integrand in the azimuth direction θ is nearly proportional to the radius A. An adaptive scheme to increase sampling points in the θ direction is therefore introduced. Numerical results show that the sampling points can be reduced by 50%. © 1994 John Wiley&Sons,

ISSN:0895-2477    

DOI:10.1002/mop.4650070605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe generation of the solution path of a parametrized nonlinear circuit represents the key step of a computer‐aided stability analysis. When this process is carried out by the Newton‐iteration‐based harmonic‐balance technique coupled with a continuation method, numerical ill conditioning occurs in the vicinity of the turning points due to the singularity of the Jacobian matrix. The Letter introduces a novel switching‐parameter algorithm allowing the turning points to be automatically detected without loss of numerical efficiency. In the neighborhood of the turning point the roles of the parameter and of one of the steady‐state harmonics are interchanged, so that the latter becomes the independent quantity. In this way the singularity is removed, and the analysis at the turning point can be performed with the same accuracy and efficiency as at any ordinary point. The switching criterion is based on the condition number of the conventional Jacobian. © 1994 John Wil

ISSN:0895-2477    

DOI:10.1002/mop.4650070606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe admittance of an open‐ended coaxial probe on a dielectric cylinder of finite thickness surrounded by a cylindrical outer layer of equal thickness but with a different dielectric constant is calculated analytically. The cylinder and the surrounding material are backed by a metal plate. The theoretical results indicate up to which frequency the measured value of the dielectric constant of the cylindrical sample remains independent of its lateral dimensions. © 1994 John Wiley&Sons, I

ISSN:0895-2477    

DOI:10.1002/mop.4650070607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractA 3D finite‐difference time‐domain (FDTD) method is used to characterize interconnections between MMIC (monolithic microwave integrated circuits) and MIC (microwave integrated circuits) modules. The scattering parameters are calculated in the 0–40‐GHz band for an interconnection between a microstrip line on a GaAs substrate (MMIC) and a microstrip line on an alumina substrate (MIC). The variation of the interconnection scattering parameters as a function of its geometrical parameters is presented. © 1994 John Wiley&S

ISSN:0895-2477    

DOI:10.1002/mop.4650070608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractWe discuss a method of evaluating the effective indices of quasimodes of a bent rectangular core waveguide taking into account the correct dielectric constant of the corner regions, which is ignored in earlier methods. At small bend curvatures and low V values, the corner regions contribute much more to the effective index change than the bending itself. © 1994 John Wiley&Sons, Inc

ISSN:0895-2477    

DOI:10.1002/mop.4650070609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractA blazed grating can be generated using a programmable liquid‐crystal television (LCTV) panel. Despite the effects of phase mismatch, phase quantization, and pixel addressing of the panel, optical beam steering is possible, particularly for small angle deflection applications. © 1994 John Wiley&Sons, I

ISSN:0895-2477    

DOI:10.1002/mop.4650070610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractMultispectral microwave radiometry for temperature reconstruction inside biological media is considered. Radiometric data on simulated living tissues have been obtained with a multifrequency radiometer in the frequency range 1.5–3.5 GHz. Temperature retrieval has been modeled as the solution of a first‐kind integral equation, based on the theory of radiative transfer. An example of temperature retrieval is reported. Results compare favorably with experimental measures. © 1994 John Wiley&Sons,

ISSN:0895-2477    

DOI:10.1002/mop.4650070611

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY