Backscatter of Electromagnetic Waves from a Rough Layer

Backscatter of electromagnetic waves from rough surfac

The Monopole Antenna With a Small Number of Radials

This paper reports a study of an antenna system consisting of a vertical monopole and a small number of insulated horizontal radials lying lightly on the ground. The monopole antenna has long been popular for medium frequency broadcasting because of its inherent simplicity and economy. Although quarter-wavelength resonant structures were used in the early days, it was shown by Ballantine (1924) that for a given power, the strongest field strength at the radio horizon was produced by an antenna about 0.6 wavelength long. This ignored the sky wave and was based on the assumption of a perfectly conducting (and reflecting) earth. With the same assumption, Brown (1935) computed the earth currents produced by a vertical monopole having a sinusoidal current distribution. He also estimated the ground power loss for a ground of infinite conductivity, assuming it had the same tangential magnetic field on its surface as when perfectly conducting. This is a reasonably good approximation under certain conditions and has been used by many writers following Brown (e.g. Wait &Surtees (1954), Monteath (1958), etc.)

Backscatter of Ultrasonic Waves from a Rough Layer

Kirchhoff approximation used to calculate backscatter of ultrasonic waves from rough laye

Variation of Electrostatic Coupling and Investigation of Current Percolation Paths in Nanocrystalline Silicon Cross Transistors

Nanocrystalline silicon thin films are promising materials for the development of advanced Large Scale Integration compatible quantum-dot and single-electron charging devices. The films consist of nanometer-scale grains of crystalline silicon, separated by amorphous silicon or silicon dioxide grain boundaries up to a few nanometer thick. These films have been used to fabricate single-electron transistor and memory devices, where the grains form single-electron charging islands isolated by tunnel barriers formed by the grain boundaries. The grain boundary tunnel barrier isolating the grains is also of great importance, as this determines the extent of the electrostatic and tunnel coupling between different grains. These effects can lead to the nanocrystalline silicon thin film behaving as a system of coupled quantum dots.& more..

The KSU Acoustic Simulator for Radar Studies

Equipment and instrumentation for acoustic simulation of electromagnetic wave propagation and radar systems design studie