A novel method for predicting site dependent specific rain attenuation of millimeter radio waves

2003 ◽  
Vol 51 (10) ◽  
pp. 2987-2999 ◽  
Author(s):  
W. Asen ◽  
T. Tjelta
Keyword(s):  
Rain Attenuation ◽  
Radio Waves ◽  
Novel Method

scholarly journals A Novel Method for Prediction of Attenuation of Millimeter Waves by Fog and Smoke

2019 ◽  
Vol 8 (3) ◽  
pp. 2080-2085
Keyword(s):  
Wave Propagation ◽  
Water Vapor ◽  
Radio Wave ◽  
Millimeter Wave ◽  
Millimeter Waves ◽  
The Other ◽  
Radio Waves ◽  
Weather Phenomenon ◽  
Novel Method ◽  
And Diffusion

Terrestrial radio wave link faces various challenges like attenuation caused by gases, water vapor and other weather phenomenon like rain, storms, snow, fog, cloud etc. These challenges are responsible for absorption and diffusion of energy. Another kind of obstacles observed by the radio waves on terrestrial path is vegetation, lamppost, grills and other urban constructions. Different phenomenon is studied under these conditions like reflection, diffraction, refraction, scattering, depolarization etc. In case of millimeter waves various propagation studies has been performed under different scenarios. More propagation studies are needed to be done especially for fog. In this paper radio wave propagation studies are performed for fog using proposed fog model and results are compared with the other model proposed in the Literature. Another propagation study is performed for smoke which is unique of its kind. This study indicates that even smoke can causes attenuation for millimeter wave frequencies.

scholarly journals Path Attenuation Calculator for Rain Fade

2019 ◽  
Vol 24 (2) ◽  
pp. 143-150
Author(s):  
Mohanad Abdulhamid ◽  
Waswa Wekesa
Keyword(s):  
Geographical Area ◽  
Rain Attenuation ◽  
Radio Waves ◽  
Weather Phenomenon ◽  
Satellite Links ◽  
Propagating Waves ◽  
Different Types ◽  
Attenuation Models ◽  
Different Levels ◽  
Specific Amount

Abstract Rain as a weather phenomenon is one of the things that greatly affects propagation of radio waves. Above 10 GHz, the attenuation brought about by the interaction of the propagating waves and the rain droplets becomes significant for both terrestrial radio links and satellite links. For this reason, rain attenuation models have been developed to aid in planning purposes for network implementation. The models use statistics to predict the attenuation that is caused by specific amount of rain and also the type of rain. This means that different regions will have different levels of attenuation due to the fact that they experience different types and amount of rain. A couple of models exist including the ITU-R, Moupfouma model, Crane attenuation model and other localized models depending on the geographical area that research data collection and extensive analysis has been conducted on and a comprehensive set of values and factors have been determined that can aid in estimation of attenuation due to rain. This paper seeks to provide a viable means by which a transmission engineer can be able to know the attenuation per kilometer due to the various models. This is achieved by designing a software calculator that provides the output of the attenuation per kilometer (dB/Km) while taking an input of rain rate for the different models available. The calculator is based on visual basic platform and works with forms.

Modeling and Characteristic Analysis of Rain Attenuation for Mobile Communication

2012 ◽  
Vol 195-196 ◽  
pp. 212-216
Author(s):  
Ai Hua Wang ◽  
Hai Min Zhang
Keyword(s):  
Mobile Communication ◽  
Mobile Station ◽  
Rain Attenuation ◽  
Base Station ◽  
Radio Waves ◽  
Characteristic Analysis ◽  
Current State ◽  
Optimized Model ◽  
Itu Model ◽  
Rainfall Attenuation

This paper firstly reviews the current state of knowledge on the effects from rain when radio waves through the atmosphere briefly. Then we describes some work being carried out by ITU to characterize rainfall attenuation in particular, and put forward an optimized model in which we lead in area overlap factor and the height relationship between base station and mobile station, to simplify the ITU model , the simulation was given by MATLAB. Finally we got results confirming the veracity of the optimized model.

scholarly journals Using Radio Wave Satellite Propagation Measurements for Rain Intensity Estimation

2018 ◽  
pp. 2-8
Author(s):  
Bernard Adjei-Frimpong ◽  
László Csurgai-Horváth
Keyword(s):  
Statistical Data ◽  
European Space Agency ◽  
Rain Attenuation ◽  
Integration Time ◽  
Radio Waves ◽  
Atmospheric Gases ◽  
Rain Intensity ◽  
Additional Information ◽  
Significant Parameter ◽  
Space Agency

The European Space Agency launched a communication satellite called Alphasat in 2013, with two experimental beacons to carry out a scientific experiment by measurement at frequencies of 19.7 GHz and 39.4 GHz respectively. Propagation through the atmosphere at these frequencies is affected by the resence of atmospheric gases and other particles like water vapour, rain and ice drops. Rain attenuation is the most significant parameter which degrades the performance of the links by absorbing and scattering radio waves that can be determined as the measured received signal power’s deviation from the nominal, non-attenuated level. Rainfall statistical data are also measured and recorded by the propagation terminals to provide additional information to apply prediction methods that require minutes of integration time rain intensity.

Radio Measurements of Coronal Magnetic Fields

1994 ◽  
Vol 144 ◽  
pp. 21-28 ◽  
Author(s):  
G. B. Gelfreikh
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Active Regions ◽  
High Sensitivity ◽  
Coronal Magnetic Field ◽  
Transverse Magnetic ◽  
Radio Sources ◽  
Radio Waves ◽  
Solar Active Regions

AbstractA review of methods of measuring magnetic fields in the solar corona using spectral-polarization observations at microwaves with high spatial resolution is presented. The methods are based on the theory of thermal bremsstrahlung, thermal cyclotron emission, propagation of radio waves in quasi-transverse magnetic field and Faraday rotation of the plane of polarization. The most explicit program of measurements of magnetic fields in the atmosphere of solar active regions has been carried out using radio observations performed on the large reflector radio telescope of the Russian Academy of Sciences — RATAN-600. This proved possible due to good wavelength coverage, multichannel spectrographs observations and high sensitivity to polarization of the instrument. Besides direct measurements of the strength of the magnetic fields in some cases the peculiar parameters of radio sources, such as very steep spectra and high brightness temperatures provide some information on a very complicated local structure of the coronal magnetic field. Of special interest are the results found from combined RATAN-600 and large antennas of aperture synthesis (VLA and WSRT), the latter giving more detailed information on twodimensional structure of radio sources. The bulk of the data obtained allows us to investigate themagnetospheresof the solar active regions as the space in the solar corona where the structures and physical processes are controlled both by the photospheric/underphotospheric currents and surrounding “quiet” corona.

The removal and morphology of intact biofilms from implanted venous access devices

1995 ◽  
Vol 53 ◽  
pp. 1020-1021
Author(s):  
M.A. Gregory ◽  
G.P. Hadley
Keyword(s):  
Patient Selection ◽  
Surgical Oncology ◽  
Venous Access ◽  
Common Procedure ◽  
Indwelling Catheters ◽  
Careful Patient ◽  
Novel Method ◽  
The Subject ◽  
Vascular Catheters ◽  
Venous Access Devices

The insertion of implanted venous access systems for children undergoing prolonged courses of chemotherapy has become a common procedure in pediatric surgical oncology. While not permanently implanted, the devices are expected to remain functional until cure of the primary disease is assured. Despite careful patient selection and standardised insertion and access techniques, some devices fail. The most commonly encountered problems are colonisation of the device with bacteria and catheter occlusion. Both of these difficulties relate to the development of a biofilm within the port and catheter. The morphology and evolution of biofilms in indwelling vascular catheters is the subject of ongoing investigation. To date, however, such investigations have been confined to the examination of fragments of biofilm scraped or sonicated from sections of catheter. This report describes a novel method for the extraction of intact biofilms from indwelling catheters.15 children with Wilm’s tumour and who had received venous implants were studied. Catheters were removed because of infection (n=6) or electively at the end of chemotherapy.

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