Radiation of transient fields from the open end of rectangular waveguide

The problem of the excitation of a rectangular waveguide by a transient current is solved in the time domain by the evolutionary equation technique and the Riemann function method. The field radiated from the open end of a rectangular waveguide is calculated in the Kirchhoff approximation using the vector potential method. The dependences of the amplitude of the radiated field on time and angle are investigated and compared with numerical results

Analysis of fields reflected from model of human body surface using artificial neural network in time domain

The problem of determination of thickness a layer of layered medium by impulse irradiation is considered. The impulse fields reflected from the model of human body surface are analyzed by artificial neural network in time domain directly. The normal incidence of plane wave with Gaussian time form on the layered medium with losses is considered. The reflected electromagnetic field is obtained by FDTD method. Initial data for neural network analysis are the values of amplitude of electrical component of reflected field. As an example, the network is trained to determine the thickness of one of the layers of the medium. The stability of the determination in presence of interferences, experimental errors and instabilities of medium parameters is investigated by numerical simulation

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

Near field of Hertzian dipole excited by impulse current

The angle dependence of near field radiated of Hertzian dipole excited by transient current is investigated. The more precise approximation in the solution for near field of the dipole is obtained in time domain by means of vector potential technique. As an example, the quickly decreasing excitation current case is considered