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Precipitation and other propagation impairments effects at microwave and millimeter wave bands: a mini survey

Kotamraju Sarat Kumar, Korada Ch Sri Kavya

Acta Geophysica

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2019

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Vol. 67, no. 2

703--719

EN

The current past has seen a sensational increment in the utilization of satellites for the applications like navigation, entertainment, media transmission, remote sensing, mobile communications, weather forecasting, defense and other purposes. These applications are assigned in the microwave and millimeter wave bands, which offer higher information transfer possibility in lesser time and use very small antennas and devices by ensuring secured and effective communications. However, beyond the 10 GHz range of frequencies these applications are generally subjected to signal losses due to various atmospheric parameters like rain, clouds, fog, hail ice and other applicable phenomena. The main factor for the signal degradation is the rainfall. The attenuation caused by rain increases with frequency, as there is increased absorption of the RF energy at higher frequencies due to water drops present along the path of the transmission; hence, the signal attenuation is more in higher-frequency bands. The other factors that induce losses in the signal are the clouds, gases present in the lower atmosphere and the different layers in the atmosphere that cause scintillation and the system losses and cable losses. This survey article abridges all outcomes related to propagation impairments and attenuation aspects at microwave and millimeter wave frequencies covering the studies of various researchers in last three decades. In addition, few of the models developed by various researchers were listed along with model parameters which are useful for the propagation engineers and others who are interested in this specialization.

2

Maximum Rain-Rate Evaluations in Aegean Archipelagos Hellas for Rain Attenuation Modeling at Microwave Frequencies

Karagianni E.Α., Vazouras C.N., Papageorgiou E.H., Sarantopoulos A.D., Nistazakis H.E.

TransNav : International Journal on Marine Navigation and Safety of Sea Transportation

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2016

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Vol. 10, no. 1

117--123

EN

By utilizing meteorological data such as relative humidity, temperature, pressure, rain rate and precipitation duration at eight (8) stations in Aegean Archipelagos from six recent years (2007 – 2012), the effect of the weather on Electromagnetic wave propagation is studied. The EM wave propagation characteristics depend on atmospheric refractivity and consequently on Rain-Rate which vary in time and space randomly. Therefore the statistics of radio refractivity, Rain-Rate and related propagation effects are of main interest. This work investigates the maximum value of rain rate in monthly rainfall records, for a 5 min interval comparing it with different values of integration time as well as different percentages of time. The main goal is to determine the attenuation level for microwave links based on local rainfall data for various sites in Greece (L-zone), namely Aegean Archipelagos, with a view on improved accuracy as compared with more generic zone data available. A measurement of rain attenuation for a link in the S-band has been carried out and the data compared with prediction based on the standard ITU-R method.

3

Investigation of Metamaterial Structure Influence on Selective Properties of Microwave Waveguide Sensor

Isteníková K., Faktorová D.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 7b

223-225

EN

The paper proposes the possibility of double negative metamaterial structure using for the transmission properties of open waveguide probe changing and the possibility of microwave open waveguide sensor tuning with metamaterial structure to be used for non-destructive testing of dielectric materials properties changing. The aim of our work was to develop a frequency selective sensor in microwave frequency band sensitive to changing of dielectric properties of investigated dielectric material.

PL

Opisano możliwość zastosowania struktury metamaterialnej posiadającej właściwości zmiany transmisji falowodu i możliwość srttrojenia czujnika falowodowego mikrofalowego. Czujnik można wykorzystać do badań nieniszczących materiałów dielektrycznych. Opracowano czujnik mikrofalowy o selektywnie zmienianej częstotliwości.

4

Modelling of scattering parameters in biological tissues

Faktorová D., Instenikoková K.

Przegląd Elektrotechniczny

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2011

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R. 87, nr 5

34-36

EN

The knowledge of electrical properties of biological materials and their interaction with electromagnetic waves is necessary for suitable determining the effect of electromagnetic field on biological systems and sequentially prevention of undesirable consequences on human organism. Because of complex heterogeneous structure of biological tissues the electromagnetic field distribution in biological systems is very complicated and depends, among others, on the type of tissue and on the presence of complicated layered structures and interfaces. With the knowledge of these electrical properties the absorption of energy and the field distribution which are the results of the solution to a boundary value problem can be obtained and simulated.

PL

Znajomość elektrycznych parametrów materiałów biologicznych i ich oddziaływania z falami elektromagnetycznymi jest niezbędna dla oceny oddziaływania pola na systemy biologiczne i ochrony organizmów przed jego niepożądanymi efektami. Ze względu na skomplikowaną, heterogeniczną strukturę tkanek rozkład pola elektromagnetycznego w systemach biologicznych jest skomplikowany i zależy, między innymi od rodzaju tkanki oraz jej kształtu. Znajomość tych parametrów umożliwia symulację pola elektromagnetycznego w organizmie i ustalenie wielkości absorbowanej energii.