A 500 m experimental range for propagation studies at millimetre, infrared and optical wavelengths

Gibbins, C.J.; Carter, D.G.; Eggett, P.A.; Lidiard, Kate A.; Pike, M.G.; Tracey, M.A.; White, Elgiva; Woodroffe, J.M.; Yılmaz, Uğur

doi:10.1049/jiere.1987.0074

Cited by 11 publications

(3 citation statements)

References 1 publication

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“…given by Gibbins et al [1987]. In this study we are primarily interested in the effects of fog droplets on wave transmission.…”

Section: Detailed Information About the Instrumentation Ismentioning

confidence: 99%

Inference of fog characteristics from attenuation measurements at millimeter and optical wavelengths

Vasseur¹,

Gibbins²

1996

Radio Science

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Measurements of fog characteristics are rare, and therefore models for predicting the attenuation caused by fog on the propagation of electromagnetic radiation are scarce. Using experimental transmissions through moderate radiation fogs on a 500‐m path, a method is developed to infer the physical characteristics of fog from concurrent attenuation measurements at millimeter, infrared, and visible wavelengths. It makes it possible to retrieve the fog drop size distribution, as well as its time evolution, during the life cycle of a fog event. It yields realistic values for fog features, such as liquid water content and average drop diameter, which are not easily measured. Furthermore, on an experimental basis, simple relationships between inferred fog characteristics and measured attenuation are proposed. It is found that while both millimetric and infrared attenuations are directly related to liquid water content, visible attenuation strongly depends on the size of the fog droplets. Overall, using these relationships together with statistical distributions of inferred fog characteristics enables predictions of fog attenuation at any wavelength from millimetric to visible.

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“…given by Gibbins et al [1987]. In this study we are primarily interested in the effects of fog droplets on wave transmission.…”

Section: Detailed Information About the Instrumentation Ismentioning

confidence: 99%

Inference of fog characteristics from attenuation measurements at millimeter and optical wavelengths

Vasseur¹,

Gibbins²

1996

Radio Science

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“…Moreover, in some cases, additional factors might further contribute to an increased value of PRF as derived from measurements. For example, some data included in the DBSG3 database were extracted from [42], in which the authors describe a propagation experiment focused on a 0.5-km terrestrial link operating at 37, 57, 97 and 137 GHz. Three rain gauges were installed along the path to monitor the precipitation during the experimental campaign.…”

Section: G Path Reduction Factor Calculation: Statistical Approachmentioning

confidence: 99%

“…Three rain gauges were installed along the path to monitor the precipitation during the experimental campaign. Samples results shown in [42] (see for example Figure 7 reporting the concurrent trend of the rain intensity and of the rain attenuation measured by the links) refer to the "path-mean rainfall rate". It is evident that averaging the rain rate along a path of 0.5 km will yield lower values than those measured by a single rain gauge, even more if the event is convective, i.e.…”

Section: G Path Reduction Factor Calculation: Statistical Approachmentioning

confidence: 99%

The Path Reduction Factor for the Prediction of Rain Attenuation Affecting Short EHF Terrestrial Links

Capelletti,

Riva,

Roveda

et al. 2024

IEEE Open J. Antennas Propag.

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The path reduction factor (PRF), a key element of semi-empirical rain attenuation statistics prediction models, is investigated to shed some light on its value for links shorter than 1 km. PRF is here calculated from simulations underpinned by the use of the Enhanced Synthetic Storm Technique (E-SST) to take into account the rain rate spatial distribution along the path. This novel approach, in contrast with the more customary one of inferring a PRF model from measurements, offers the advantage of avoiding considering any unwanted additional attenuation not due to precipitation, but typically linked to systeminduced effects. Results indicate that, as expected, PRF reduces with the increase in the rain rate R and in the path length L, and they also reveal quite a marginal dependence on the operational frequency. Most importantly, the outcomes highlight that the maximum values of PRF only slightly exceeds 1 and, in addition, they provide a possible explanation as to why, on the contrary, the path reduction factor defined in the Recommendation ITU-R P.530-18 is characterized by a steep increase as L reduces.

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Modeling of raindrop size distributions from multiwavelength rain attenuation measurements

Maitra¹,

Gibbins²

1999

Radio Science

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Abstract. Techniques for modeling the distribution of raindrop sizes, in terms of the lognormal and modified gamma distribution, from multiwavelength rain attenuation measurements at millimeter and infrared wave bands have been demonstrated. In order to obtain the three-parameter lognormal distribution, three experimental measurements are required, which can be attenuations at two frequencies and rain rate. Three measurements are used to form three equations, which are treated as nonlinear and are solved using a numerical technique to obtain the distribution parameters. The gamma distribution is treated as a two-parameter distribution, taking a fixed value of 2 for the index. The two parameters of the gamma distribution are obtained from measurements of rain rate and infrared attenuation following the technique described by Maitra and Gibbins [1995]. From an analysis of two rain events it is found that the measured attenuations at millimeter wavelengths show somewhat better agreement with the calculated attenuations obtained from the lognormal distribution than from the modified gamma distribution. The gamma model gives higher number densities for small drops than those given by the lognormal model. IntroductionThe distribution of raindrop sizes has been a subject of continued interest with the availability of more data from different locations. The suitability of a technique for DSD measurement,depends on the type of application. Direct measurements using a distrometer have limitations, given that it gives a localized measurement and that the impact distrometer has a relatively large time constant (---1 min). Radar measurements of DSD are suitable for obtaining a picture throughout the vertical extent of rain. The average DSD over a certain 657

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A 500 m experimental range for propagation studies at millimetre, infrared and optical wavelengths

Cited by 11 publications

References 1 publication

Inference of fog characteristics from attenuation measurements at millimeter and optical wavelengths

Inference of fog characteristics from attenuation measurements at millimeter and optical wavelengths

The Path Reduction Factor for the Prediction of Rain Attenuation Affecting Short EHF Terrestrial Links

Modeling of raindrop size distributions from multiwavelength rain attenuation measurements

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