Amplitude and phase scintillation measurements on 8.2 km line-of-sight path at 30 GHz

\u3cp\u3eThe letter summarises results of amplitude and phase scintillation measurements at 30 GHz on an 8.2 km line-of-sight path in the Netherlands. The measured results compare favourably with those obtained from weak-scattering theory.\u3c/p\u3

Evaporation derived from optical and radio-wave scintillation

\u3cp\u3eThe determination of the evaporation from scintillation measurements at several wavelengths is discussed. The refractive-index structure parameter C\u3csub\u3en\u3c/sub\u3e \u3csup\u3e2\u3c/sup\u3e derived from the observed amplitude scintillation on a 30-GHz radio link is compared to a spot measurement of this quantity at a much lower height than that of the radio link. After free convection height scaling, a difference of a factor of 3 is found. This factor is discussed. A calculation of the evaporation from the observed radio-wave scintillation yields good agreement with calcu­lations based on the Priestley-Taylor formula.\u3c/p\u3

Millimeter-wave Fresnel-zone plate lens and antenna

A new variety of millimeter-wave Fresnel-zone plate lens with enhanced focusing quality is described. Each full-wave zone of the lens is divided into four quarter-wave subzones, which are covered by dielectric rings having equal thickness but different permittivities. More practical equations are derived for the radii of the zones, and for the thickness of the lens by taking into account the angle of incidence of the electromagnetic wave. A Fresnel-zone plate antenna (FZPA) consisting of a quarterwave lens and a scalar feed is developed and analysed theoretically. Equations for the aperture field and far field are derived using multiple ray tracing through dielectric plates and vectorial Kirchhoff diffraction theory, respectively. It is demonstrated that the proposed transmissive-type FZPA has an aperture efficiency of more than 50% in the 60 GHz frequency band. This computed efficiency agree with the measured overall efficiency reported by other researchers for an X-band quarter-wave reflector-type FZP

Modal transmission-line calculation of shielding effectiveness of composite structures

A novel modal transmission-line (MTL) method for the calculation of the shielding effectiveness of composite structures is presented. The MTL results are compared with the results obtained by another numerical technique. The new model is characterised by simplicity and accuracy and provides an opportunity for easy extension to laminated composite structure

Quarter-wave Fresnel zone plate lens and antenna

A new variety of the Fresnel zone planar lens with enhanced focusing quality is proposed. Each full-wave zone is divided into four quarter-wave subzones, which are covered by dielectric rings having equal thickness but different permittivities. Based on this planar lens configuration, a transmissive-type Fresnel-zone antenna for DBS-reception with more than 50% aperture efficiency is developed and examined theoreticall

Characterization of radio wave propagation into buildings at 1800 MHz

The paper presents the results of signal strength measurements at 1800 MHz in four office buildings in The Hague, illuminated by an outdoor base station with an antenna above the rooftop. The objectives of these experiments are to study the behavior of the received signal strength at different floors of a building and to determine the main characteristics concerning cell coverage, namely, signal attenuation and variation within these buildings. It is shown that large fluctuations occur between average signal levels in line-of-sight (LOS) and non-LOS areas of multifloor buildings

Modelling of angular dispersion due to rough surface scattering for implementation in ray-tracing-based propagation prediction tools

This paper describes the modelling of scattering caused by irregular surfaces as a basis for im-plementation in ray-tracing methods. An approach is presented in a first attempt to model the dispersive effects, caused by scattering on surfaces which have random irregularities, directly at the receiver. The method is based on assigning an effective stochastic roughness to a specific surface. The scattering effects caused by the surface roughness include the combined effects of both the surface irregularities and changes in material properties. The possibility of including the model into a 3-D ray-tracer is outlined. The results of simulations and measurements show that the method can be used to model the dispersive effects of rough surface scattering in a manner similar to using the reflection reduction factor for Gaussian surfaces, except that the reduced power in the specular direction is distributed in the angular domain