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Cylindrical (with axial symmetry) vector beams are great interesting practically due to a variety of applications, including microscopy, lithography, electron acceleration, material processing, high-resolution metrology, micro-ellipso-metry and spectroscopy. Intracavity methods and approaches for shaping beams with complex spatial polarization structure are practically absent in the terahertz range...
Cylindrical vector beams have a great number of applications, including electron acceleration, material proces-sing, high-resolution metrology, microellipsometry and spectro-scopy. Methods and approaches for forming beams with complex polarization structure are practically absent in the terahertz range. Using Body of Revolution Finite Difference in Time Domain (BOR FDTD) method the reflection and...
Transient radiation of a dipole corresponds to excitation of a spherical harmonic wave in some conical line from an evanescent wave domain. The governing equation contains a cut-off frequency that depends on radius. Using high refraction index material the cut-off frequencies for the radiating mode can be significantly reduced. This can lead to “tunneling” energy from the evanescent region and consequently...
During the propagation of pulse signal in dielectric waveguide Fast Pulse Guided Wave is forming. This wave propagates at the head of pulse signal in the waveguide and has rhombus-shape field distribution inside the dielectric with inclined like-Cherenkov wave front. Another part of this wave propagates near the dielectric surface in free space with the speed of light in free space. The rhombus shape...
Propagation of transient electromagnetic waves in dielectric (optical) waveguides has not been studied sufficiently yet. Such signals can be used for increasing the communication channel capacity. So the aim of this paper is to reveal physical processes that occur with excitation and propagation of pulse signals in such waveguides.
Design of efficient electrically small antennas is very important for miniaturization of radio communication devices. However besides some technical difficulties there is a fundamental problem: an antenna with the size much smaller than the wavelength cannot radiate efficiently. As a result for an antenna there exists a lower cut-off frequency fc. For frequencies f<fc an antenna cannot radiate...
Pulse signal propagation in an open circular dielectric waveguide was considered in Time Domain. The field partition into a guided wave, a radiated wave, and a pulse surface wave was observed. A precursor creation by the pulse surface wave in the dielectric waveguide is shown. In order to study long-time behavior of this wave a moving frame with BOR-FDTD method was used. A pure pulse wave can be excited...
Pulse radiation of TEM horn antennas with different tapering profiles was simulated and the effects of tapering on the near fields, radiated fields, and the return losses are discussed. Some considerations about the ways to improve TEM horn characteristics are presented.
The paper considers generalization of Mode Basis Method for calculation of pulse signal propagation in a circular open dielectric waveguide. The mode functions are calculated by Integral Equations Method. It is shown that the circular dielectric waveguide possesses only continuous spectrum. Then an integral-differential System of Evolutionary Equations is obtained that describes mode amplitudes evolution...
A lot of electromagnetic problems that require application of Time Domain (TD) methods have appeared recently. Among such is the problem of pulse signals propagation in open dielectric waveguides. This problem emerges in analysis of ultrashort pulse propagation in optic and photonic waveguides (fibers), pulse radiation of dielectric rod antennas.
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