This paper presents an approach for the design and optimization of pseudo-gradual transitions in circular waveguides using the genetic algorithm (GA). The characterization of these transitions is carried out by the mode-matching method. This method, associated with the generalized scattering matrix technique, leads to determine the reflection coefficient on the useful band of the studied struct...

One-way wave operators are powerful tools for forward modeling and inversion. Their implementation, however, involves introducing the square-root of an operator as a pseudo-differential operator. A simple factoring of the wave operator produces one-way wave equations that yield the same traveltimes as the full wave equation, but do not yield accurate amplitudes except for homogeneous media and ...

Electromagnetic Band Gap (EBG) structures are nonperiodic structures that show unique electromagnetic features, such as frequency band gap for surface waves and in-phase reflection coefficient for incident plane waves, which makes them desirable for low-profile antenna designs. A very innovative topic for antenna scientists and engineers are the applications of EBG structures in antenna designs...

There has been considerable progress in the construction of fundamental bandwidth limits and near optimal design realisations for several classes of passive linear electromagnetic wave devices, most notably for radar absorbent materials, antennas and meta-materials. This article seeks to place balun design on a similar footing, for an important class of baluns; in particular those which are ‘pe...

In this work we present a Schottky diode grid mixer suitable for mixing or detecting quasi-optical signals. The mixer is a planar bow-tie grid structure periodically loaded with diodes. A simple transmission line model is used to predict the reflection coefficient of the grid to a normally incident plane wave. The grid mixer power handling and dynamic range scales as the number of devices in th...

BACKGROUND Systolic blood pressure and pulse pressure are substantially higher in older adults. The relative contributions of increased forward versus reflected pressure wave amplitude or earlier arrival of the reflected wave to elevated pulse pressure remain controversial. METHODS AND RESULTS We measured proximal aortic pressure and flow, forward pressure wave amplitude, global wave reflecti...

The reflection coefficient of longitudinal 25-GHz phonons at a quartz-liquid 4He interface was measured for various phonon intensities. For thoroughly cleaned quartz surfaces a reflection coefficient of I independent of the incident intensity was found. When the sample was covered with a thin hydrocarbon film, however, the reflection coefficient dropped by typically 5-10% when the phonon intens...

This paper introduces an optical measurement system for shock wave characteristics. The system works by mountinga metal plate attached to spring mounts against the shock wavefront. This set is sealed and can plot the shock wave pressure diagram by measuring plate's displacement, radiation and changing the reflection of light during shock wave conflict, and converting these optical data to volta...

In this paper, the reflection and refraction of longitudinal wave from a plane surface separating a micropolar viscoelastic solid half space and a fluid saturated incompressible half space is studied. A longitudinal wave (P-wave) impinges obliquely at the interface. Amplitude ratios for various reflected and transmitted waves have been obtained. Then these amplitude ratios have been computed nu...