I. P. Kovalyov, N. I. Kuzikova

In the paper the problem to build universal discrete model for antenna-s radiation pattern in a frequency band is considered. In order to solve this problem, the theory of resonant modes for the external electrodynamic problem is used. Main statements of this theory and formulas, which describe amplitudes of the resonant modes in dependence on frequency, are written. The field excited by antenna is determined by radiation of the induced in it currents of three types: the electric current of conductivity, the electric current of displacement, and the magnetic current. Relations of these currents with resonant modes are shown. Components of these currents were represented in a form of the Fourier expansion. Coefficients of the Fourier series represent discrete parameters of the antenna model. The model also includes complex resonant frequencies of the modes. Formulas, which describe fields and radiation pattern by means of model-s parameters, have been obtained. The proposed model is universal, it can be applied for arbitrary antenna which has finite spatial sizes. The symmetric vibrator in a form of the thin conductor with infinite conductivity is analyzed as an example. Results of the numerical analysis for it confirm the theoretical results.