Impulse irradiation of layered medium by the open end of circular waveguide
The radiation of impulse signal from the open end of a circular waveguide is considered by analytical and direct numerical methods. The radiation of short pulse from the aperture is considered by calculation of special time form of field by means of modal basis method that permits to transform the nonstationary three-dimensional electrodynamic problem into the problem for one-dimensional evolutionary equations by means of the construction of modal basis for electromagnetic field with arbitrary time dependence. The method is applied to solve the problem of pulse evolution for positive and negative time with the use of Laplace transform by construction of operator of propagation. The approach is employed to form the short pulse on aperture of circular waveguide for irradiation of layered medium with losses.
Transient radiation from the open end of circular waveguide
The transient radiation from the open end of a circular waveguide is considered by simple analytical and direct numerical methods. The radiation of short pulse from the aperture is provided by calculation of special time form of field by means of modal basis method that permits to solve the problem of pulse evolution for positive and negative time with the use of Laplace transform. The radiation of the short pulse is calculated in Kirchhoff approximation and simulated by FDTD method. The frequency characteristics of the radiated field are considered.
Propagation of Spherical Transient Electromagnetic Wave Through Radially Inhomogeneous Medium
The nonstationary three-dimensional electrodynamic problem is transformed into the problem for one-dimensional evolutionary equations by means of the construction of modal basis for electromagnetic field with arbitrary time dependence. Transient electromagnetic fields in infinite space filled with inhomogeneous in radial direction transient medium without losses are presented by spherical modes. The completeness of the basis is proved by means of Weyl's theorem about orthogonal splitting of Hilbert space. The expansion coefficients of transient electromagnetic field are found from the set of evolutionary equations which describe independent propagation of the modes. The transient electromagnetic field can be found directly without Fourier transform