A new method of designing horn-fed frequency scanning holographic antenna is proposed. The artificial surface design of holographic antenna is based on generalized law of reflection. The input admittance is utilized to construct the interference pattern of the surface which is intervened by the excitation wave and the required radiation wave. The scalar admittance unit cell which is composed of...

We compute time-periodic and relative-periodic solutions of the free-surface Euler equations that take the form of overtaking collisions of unidirectional solitary waves of different amplitude on a periodic domain. As a starting guess, we superpose two Stokes waves offset by half the spatial period. Using an overdetermined shooting method, the background radiation generated by collisions of the...

The radiation efficiency of an infinite flat panel which is radiating an infinite plane wave into an infinite half space can be shown to be equal to the inverse of the cosine of the angle between the direction of propagation of the plane wave and the normal to the panel. The fact that this radiation efficiency tends to infinity as the angle tends to 90° causes problems with simple theories of s...

The paper deals with a new mechanism of instability in stratified fluid caused by internal wave radiation from a shear layer. This radiation instability may be explained in terms of the negativeenergy wave concept. These waves are able to grow due to radiation losses. The dispersion relation and non-linear stage of the process are analyzed through a model with tangential velocity discontinuity....

The field of radiation emission from electron beams is reviewed with special reference to work related to free-electron lasers. Different schemes o f interaction in periodic structures, electromagnetic slow-wave structures, and in transverse confining force are distinguished. Various effects and devices such as traveling wave amplifiers, Smith-Purcell radiators, Cerenkov and bremsstrahlung-free...

High-gain and low-profile antennas are required for high-speed wireless communication systems and mechanically-scanning automotive radars in the millimeter-wave band. Waveguide antenna is one of the most attractive planar antennas for such millimeter-wave systems because of its low loss and high efficiency characteristics in high frequency band. Travelling-wave excitation is more effective for ...

In this paper the radiation property of the one-dimensional periodic leaky-wave structure is analysed using a new hybrid method, which involves the mode expansion method for expanding the periodic aperture field in terms of spatial harmonics and the method of effective radiation sections for transforming the expanded fields into far fields. Using this method, the radiation of each spatial harmo...

The phenomenon of the polarization suppression of X-ray Umweg multiple waves in Renninger scans [Renninger (1937). Z. Kristallogr. 97, 107-121] of crystals, showing intensity decrease due to properly chosen wavelength and polarization of incident radiation, is observed. That is, one of the participating wave components in the multiple-wave interference is reduced considerably so that the intens...

The radiation characteristic of plasma antenna is investigated by using the finite-difference time-domain (FDTD) approach in this paper. Through using FDTD method, we study the propagation of electromagnetic wave in free space in stretched coordinate. And the iterative equations of Maxwell equation are derived. In order to validate the correctness of this method, we simulate the process of elec...