infinite impedance cone are reduced. It is shown that the considered problem is reduced
to solving a non-oscillating integral equation. The case of electromagnetic wave
diffraction by a solid impedance cone is considered separately. Application of Watson-
Bessel and Sommerfeld integrals in work [13] has allowed obtaining a model of
perfectly conducting conical surface with azimuthal slots.
The mathematical apparatus of the research of a boundary value problem of cone
excitation is based on using the Green function for a cone with transverse slots.
Modeling of transverse slots by impedance tapes the expressions for slot conductivity
are obtained and dependences of real and imaginary parts of conductivity on slots
position on conical surfaces are studied. As a result of the researching the boundary
electromagnetic value problem in rigorous statement author of work [14] received
representations for Debye potentials. Through these potentials components of
electromagnetic fields at diffraction of a plane wave by the unlimited perfectly
conducting plane angular sector are expressed. Properties of diffraction coefficients
and spectral functions which are solutions of the boundary Laplace-Beltrami
eigenvalue problem were studied.
For solving the first and second boundary value problems for the Helmholtz
equation with the solid finite cone geometry authors of work [15] have used the
rigorous analytical-numerical method based on application of a regularization and
factorization methods. It is shown that the model problem of acoustic wave diffraction
by the solid finite cone is reduced to solving the infinite system of the linear algebraic
equations. The obtained numerical solution of the reduced system has allowed to study
characteristics of the scattered field in the wide range of variation of frequency
parameter.
On the basis of the performed analysis it is possible to draw a conclusion on the
relevance of research of model boundary value problems of wave diffraction by conical
structures and their varieties. Creating the new and development of the existing
approaches and methods of the solution of mathematical problems for cones with
different surface properties (surface impedance, transparency of the sides, existence of
surface heterogeneity including slots) will allow to obtain solutions of correspond
model physical problems and to study features of the considered physical processes of
fields and such objects interaction. Results of the performed researches can be
effectively used in designing and creation of modern radio physical, radio engineering,
acoustic devices, systems and complexes.
Problem formulation. The single periodical conical gratings
with the period
l
consisting of
N
conical strips is located on a semi-infinite circular conical surface
with opening angle
2
and situated in the field of the harmonic (monochromatic)
source of spherical waves (Fig. 1) that placed at a point
0
B.
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