Selective Fading of Microwaves

Crawford, A. B.; Jakes, William C.

doi:10.1002/j.1538-7305.1952.tb01376.x

Cited by 60 publications

(13 citation statements)

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“…Crawford wrote about point-to-point propagation experiments performed at microwave frequencies in 1952 [44]. His experiment focused on fading in the point-to-point link, specifically evaluating how fading varied across frequencies.…”

Section: Radio Propagation Experimentsmentioning

confidence: 99%

A Technique for Evaluating the Uncertainties in Path Loss Predictions Caused by Sparsely Sampled Terrain Data

Davis¹

2013

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Radio propagation models provide an estimate of the power loss in a communication link caused by the surface of the ground, atmospheric refraction, foliage, and other environmental factors. Many of the models rely on digital topographic databases to provide information about the terrain, and generally the databases are sparsely sampled relative to the electromagnetic wavelengths used for communication systems. This work primarily develops a technique to evaluate the effects of that sparsity on the uncertainty of propagation models.That is accomplished by accurately solving the electromagnetic fields over many randomly rough surfaces which pass through the sparse topographic data points, many possible communication links, all of which fit the underlying data, are represented. The power variation caused by the different surface realizations is that due to the sparse sampling. Additionally, to verify that this solution technique is a good model, experimental propagation measurements were taken, and compared to the computations. The experimental work presented in Chapter 7 required the help of many individuals from VT, NSWC, and NRAO. In addition to Ben and Dr. Brown, Wes Sizemore at NRAO, and Bruce Naley, Punk Chilton and Natasha Lagoudous from NSWC all put in lots of work during the weeks conducting the experiment. Bruce was invaluable for climbing 100 feet up the water tower, with the antenna and spectrum analyzer, to take measurements. Additionally, equipment was provided by NSWC, and many at NRAO provided help in experiment planning, regulatory approval, and scrounging for parts, and fixing broken equipment.iii

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Section: Radio Propagation Experimentsmentioning

confidence: 99%

A Technique for Evaluating the Uncertainties in Path Loss Predictions Caused by Sparsely Sampled Terrain Data

Davis¹

2013

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“…Wideband channel sounders are often used to study broadband wireless channels. Channel sounding take many forms and the systems that are used have evolved in parallel with the interest in wireless communication [27][28][29]. Some techniques, such as pulse or frequency swept transmissions, have been widely used in many measurement studies [30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Wideband Sounder for Dynamic and Static Wireless Channel Characterisation: Urban Picocell Channel Model

Ndzi¹,

Stuart²,

Toautachone³

et al. 2011

PIER

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Abstract-This paper presents a high speed configurable FPGAbased wideband channel sounder with signal bandwidths up to 200 MHz and results of a study of dynamic urban picocell channel. The use of FPGA allows the sounder to be adaptable for measurements in different scenarios. Adaptable options include changes to the waveform, bandwidth, channel sampling rate and real-time averaging to improve signal-to-noise ratio in weak signal conditions. The implemented architecture has led to a 60% reduction in size and weight compared to sounders in use elsewhere making it ideal for mobile channel measurements. The study of an urban picocell channel has shown that dynamic variation due to automotive traffic introduces average signal fades of up to 5 dB but causes frequency selective fading with depths of up to 40 dB. Existing channel models assume antenna heights of more than 6 m and path lengths of more than 30 m. Therefore there is a need for shorter path models and this paper proposes a linear picocell channel model for static and dynamic urban environment.

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“…In modern microwave radio systems, protection requirements are frequently governed by the presence of multipath fading, 2 "' 3 as opposed to causes associated with equipment or human intervention. 1 Esti mates of service failure time due to multipath fading are therefore needed to determine the adequacy of diversity protection arrange ments when new routes are planned, when transmission parameters of existing routes are changed, or when alternate protection strategies are considered for future use.…”

Section: Introductionmentioning

confidence: 99%

Transmission Unavailability of Frequency-Diversity Protected Microwave FM Radio Systems Caused by Multipath Fading

Vigants¹,

Pursley²

1979

Bell System Technical Journal

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Selective Fading of Microwaves

Abstract: The results of an extended survey of microwave propagation over two lineof-sight paths in New J crsey arc described. Angle-of-arrival

Cited by 60 publications

References 0 publications

A Technique for Evaluating the Uncertainties in Path Loss Predictions Caused by Sparsely Sampled Terrain Data

A Technique for Evaluating the Uncertainties in Path Loss Predictions Caused by Sparsely Sampled Terrain Data

Wideband Sounder for Dynamic and Static Wireless Channel Characterisation: Urban Picocell Channel Model

Transmission Unavailability of Frequency-Diversity Protected Microwave FM Radio Systems Caused by Multipath Fading

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