State-of-the-art in the theory of antennas with non-linear elements
DOI:
https://doi.org/10.1109/ICATT.1995.1234104Abstract
Various types of antennas, elements with nonlinear characteristics being part of them, are increasingly brought into practice today. The correct analysis of such antennas is possible only with the methods taking into account the properties and interconnection of all, linear and nonlinear, antenna elements.
The paper concerns theoretical methods of antenna with nonlinear elements (ANE) analysis based on approach using the state variables. Several kinds of the state equations and antenna output equations are given. Their peculiarities are analyzed in terms of feasibility of numerical or analytical solution.
A special consideration is given to a recently developed procedure of the state equations analytical solution with the Volterra-Winner series in the matrix representation. It is shown that it is possible to build a structural ANE model using the analytical solution of the state equations. The ANE structural models of various levels of rigor, namely the linear model, and the models for the second and third order responses are analyzed. The given models are obtained on the basis of a general model simplification. They allow to estimate fast and to interpret physically the effects arising in such antennas. The most advantageous fields of application of the developed structural model are indicated.
The possibilities to analyze antennas with the distributed nonlinear elements are also considered. A problem of a thin wire antenna with nonlinear boundary conditions satisfied on its surface, is cited as an example of such a problem. The range of problems where the distributed nonlinear elements can be considered as a lumped nonlinearity is outlined. The existing approaches to solving such problems are discussed.
