ISSN:0894-3370    

DOI:10.1002/jnm.1660010102

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe use of models in giving meaning to sense data is described. It is shown that models are essential to human understanding, but that there are no uniquely ‘best’ models. This leads to the discussion of the design of suitable models for engineering use. The role of physical and mathematical models is mentioned, and attention is drawn to geometrical and physical features. It is stated that numerical methods have overriding advantages, one of which is the possibility of numerical experimentation. The modelling of vector fields is discussed and attention is drawn to the ideas of differential geometry which attach the vector field to the space in which it acts. It is shown that variational methods, together with numerical experiments, can be used to derive invariant parameters which give both global and local information about electromagnetic systems in a particularly economical method of computat

ISSN:0894-3370    

DOI:10.1002/jnm.1660010103

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe principal features of the modified TLM method such as the asymmetrical condensed node, graded mesh and dispersion characteristics, are briefly presented. Its general application to multiaxial discontinuities in quasi‐planar structures is described, and the modelling of bilateral finline T‐junctions is demonstrated in particu

ISSN:0894-3370    

DOI:10.1002/jnm.1660010104

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe Boltzmann transport equation is used to derive a set of conservation equations which is capable of describing the electron transport phenomena in a single‐valley semiconductor. These conservation equations are averaged over the different valleys of the conduction band to develop another set of equations that can be used to describe accurately the electron transport phenomena in a multi‐valley semiconductor, such as GaAs, using the equivalent single‐electron gas model whose characteristics are the average weighted characteristics of the constituent gases. The nonstationary effects are included by using energy dependent mobility and electron temperature functions. This program is used to simulate a GaAs MESFET with a 0·5 μm gate length and a 0.2 μm thick active layer. The active layer is doped at 1017cm−3. A travelling Gunn domain is observed between the gate and the drain. The domain oscillation frequency is much higher than the normal operating frequency of the MESFET. The domain formation's dependence on the gate bias and the active layer thickness are also

ISSN:0894-3370    

DOI:10.1002/jnm.1660010105

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe coupling between incident electromagnetic fields and lossless multiconductor transmission systems is studied using transmission‐line modelling‐(TLM) and the impedance parameters of the transmission system. This calculation is a two‐stage procedure:firstly, the field problem is solved, with no conductors present, to give the incident fields; secondly, the multiconductor transmission‐line problem is solved using equivalent voltage and current sources representing coupling from the incident fields. Comparison of these results with previously published work shows excellent agreement. The numerical model presented is particularly suitable for studying electromagnetic compatibility p

ISSN:0894-3370    

DOI:10.1002/jnm.1660010106

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe conventional transverse resonance method, which has been widely used for the approximate characterization of a number of guiding structures and leaky wave antennas, is formulated in a generalized form. The transverse resonance viewpoint combined with the generalized matrix representation of discontinuities yields a rigorous transverse equivalent circuit of the guiding structure.This technique is used to compute the characteristics of both symmetrical and asymmetrical double slot unilateral finlines in terms of phase constant and characteristic impedance of the dominant as well as higher‐order modes. Numerical aspects of this method are discussed.In a double‐slot finline structure, a coupled‐mode regime is established with the onset of the first higher‐order mode in addition to the dominant quasi‐TEM mode. Symmetrical structures are simply modelled in terms of even and odd mode characteristics, but a more general coupled‐line model, in terms of the C‐mode and the II‐mode must be applied to asymmetrical c

ISSN:0894-3370    

DOI:10.1002/jnm.1660010107

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractTwo‐ and three‐dimensional electromagnetic resonance calculations have been performed on rising‐sun magnetron structures. These calculations have been made using the transmission‐line matrix method. Cylindrical coordinates have been used in order to facilitate modelling of the essentially cylindrical device. Recent improvements to the TLM technique, such as the development of the symmetric condensed node for electromagnetics, have been fully exploited. The numerical procedure is described, the modelling process is discussed, and the results obtained are evaluated in comparisons with corresponding empiric

ISSN:0894-3370    

DOI:10.1002/jnm.1660010108

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0894-3370    

DOI:10.1002/jnm.1660010101

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY