Campi Elettromagnetici - Articolo funzione di Green

1057

IEEE TRANSACTIONS 36, NO. 8,

ON ANTENNAS AND PROPAGATION, VOL. AUGUST 1988 for

Spectral Dyadic Green’s Function Formulation

Planar Integrated Structures

more realistic model of the excitation of the integrated

Abstract-The dyadic Green’s function, transformed in the Fourier

a planar integrated structure

domain, is evaluated in the general case of structure must take into account, in a correct way, the

fed by distribution of tridimensional electrical sources arbitrarily

a presence of tridimensional sources, generally located in the

the basis

located in the dielectric substrate. The analysis is carried out on layers. Moreover, it should be pointed out that the vertical

of the Maxwell’s equations written for the time variation and

e)*‘ component of the feeding source has a relevant influence in the

transformed in the Fourier domain. The elements of the spectral dyadic evaluation of the losses of the structure and on the radiation

Green’s function are evaluated via the transmission-line analogy by

making of very general equivalent circuits of the planar structure

use pattern.

determined for the case of transverse electric (TE) and transverse Only recently some examples of study of microstrip

a

(TM)

magnetic waves according to general tridimensional source structures based on the spectral analysis have appeared in

excitation. General properties among the elements of the Green’s technical literature. The first paper dealing with the full wave

function are obtained, due to the electrical and geometrical symmetry of

the structure, and the different roles played by the independent terms of approach concerning the aforementioned problem was pre-

are

the matrix discussed. An expression for the power produced by the 121,

sented by Itoh in where the evaluation of a partial set of

[

sources, evaluated through its spectral power density, is derived, and the the dyadic Green’s function is obtained under the hypothesis of

formal representations in the Fourier domain of the input impedance for planar sources located at the interface. However, the study is

vertical and transverse sources are presented. mainly focused on the eigenvalue problem of the structure,

INTRODUCTION

I. and limited interest is given to the radiated fields. Papers

oriented in the study of tridimensional feeding sources can be

I

T IS WELL KNOWN that microstrip integrated circuit [19], [20]

found in where the theoretical approaches are

(MIC) antennas are now largely used in the microwave and different from the full wave theory. Recently, Chi and

millimeter wave frequency bands due to their intrinsic [21] presented a paper dealing with the radiation

Alexopoulos

advantages with respect to the mo