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Microwave Attenuation Studies Due to Rain for Communication Links Operating in Malaysia
2005
Attenuation due to rain is an important constraint in the designing of the microwave communications links operating in Malaysia especially at frequencies above 10 GHz. In recent studies, the ITU-R proposed models for the prediction of rain attenuation give a good estimation for the microwave propagation loss caused by rain for the temperate regions but it underestimates the rain attenuation prediction for the tropical regions. This paper studies the rain attenuation prediction models for the design of microwave terrestrial line-of-sight (LOS) systems and the results of this investigation.
The effects of atmospheric circulation on line-of-sight microwave links
Radio Science, 1995
This paper presents an investigation of a lake-land breeze atmospheric circulation responsible for strong horizontal and vertical inhomogeneities of moisture distribution which affected the refractivity in the neighborhood of a microwave line-ofsight link, as observed during a multi-instrument radiometeorological experiment carried out in Sao Paulo, Brazil. A boundary layer and mesoscale atmospheric model was used to simulate the local circulation within the link region and to compute the time evolution of the vertical structure of the atmospheric refractive index. A ray-tracing model was also used to calculate the intensity of the received signals from the measured refractive index vertical profiles. The integrated simulation results were then compared with the measurements. The good agreement obtained between the measured and the simulated characteristics of the temperature and moisture advection, as well as between the measured and the calculated received signal levels, indicates that the lake-land breeze circulation mechanism is a likely source of the propagation phenomena observed in the microwave link.
Comparison of Microwave Path Lengths between Temperate and Tropical Region Based on Effects of Rain
— Rain is a major source of attenuation for microwave propagation above 7 GHz. The problem of rain attenuation prediction has been studied along the years. In spite of the effort developed in different parts of the world, there are yet some points to be clarified. This problem is quite difficult to be solved, mainly due to the complexity of rain structure. This clearly suggests that reduction factor is the major yardstick for comparing rain attenuation prediction models. However, important parameter need to consider in the path reduction factor is the maximum effective path length for a particular link at specific operating frequency. This paper presents the summary of allowable path length for designing terrestrial microwave link at particular operating frequency at temperate and tropical region. The objective of this paper, to establish the maximum path length or hop length for terrestrial link on line of sight point to point communication at 99.99% of availability. Various frequency band such as 7 GHz, 15 GHz, 23 GHz, 26 GHz and 38 GHz been investigated using the ITU-R path reduction model. From the studies conducted, there are significant differences in path length between temperate region and tropical region. The differences are 22 km, 10 km, 5 km, 4 km and 3 km in the path length for operating frequency 7 GHz, 15 GHz, 23 GHz, 26 GHz & 38 GHz. This paper will provide useful information for microwave engineers and researchers in making valuable decision on path length for any terrestrial links point to point communication operating in a temperate and tropical region in future.
31st URSI General Assembly and Scientific Symposium
Multipath fading is an important constraint on the prediction of path loss for terrestrial line-of-sight microwave links. The International Telecommunication Union - Radiocommunication (ITU-R) Rec. P.530 [1] is one of the most widely used methods providing guidelines for the design of terrestrial line-of-sight links. The purpose of the study presented in this paper is to make an investigation of the effect of both terrain roughness and geoclimatic factor parameters in the path loss characteristics of microwave line-of-sight (LOS) propagation in NATO Band 3+ (1350 - 2690 MHz) and NATO Band 4 (4440 - 5000 MHz) frequency ranges. The two parameters led to significantly different results for the link availability due to multipath fading as a function of the fade margin.
IJERT-Improved Microwave System for Modern Communication
International Journal of Engineering Research and Technology (IJERT), 2014
https://www.ijert.org/improved-microwave-system-for-modern-communication https://www.ijert.org/research/improved-microwave-system-for-modern-communication-IJERTV3IS060718.pdf In order to improve the rate of signal losses in communication, the need for an improved microwave communication comes into play. Microwave communication has actually replaced other forms of communication because of its high band width, effective and low-cost installation, manipulation and maintenance. The other forms of communication exist but none has effective line of sight (LOS) compared to microwave which can travel over rough terrain and unfriendly climatic conditions. Although other sources of transmission require large expanse of land area, microwave communication requires only limited amount of space. Site size is mainly governed by the antenna cable requirements. In this work, several challenges as well as recommendation are outlined.
Investigation of propagation over terrain
2014 24th International Conference Radioelektronika, 2014
Results of long term measurements of atmospheric refractivity profiles and microwave propagation are used for comparison with an improved analysis of propagation over irregular terrain using physical optics approximation of vector problem, which offers more reliable numerical simulations for low altitude propagation and diffraction field zone without any auxiliary procedures.
Survey of Available Experimental Data of Radio Wave Propagation for Wireless Transmission
IEEE Transactions on Antennas and Propagation, 2018
This paper provides a survey of the various experimental data available on the value of the propagation path loss of radio waves in a cellular wireless environment. It is shown starting with the Okumura et al.'s paper [1] on propagation measurements and other available published experimental data, that they all exhibit that the electric field varies as ρ-1.5 within a cellular radius of a few kilometers, where ρ is the radial distance of the receiving antenna from the transmitting one. This decay in the fields is equivalent to a propagation loss of-9 dB/octave or-30 dB for a decade of the distance. This value is independent of the nature of the ground, whether it be composed of rural, urban, suburban or water. This is the first time it is stated that the propagation path loss due to the presence of ground generates a path loss of 90 dB when the signals travel a distance of 1 km. This value is rather large when compared to a loss of 30-50 dB produced by buildings, trees and similar artifacts. Therefore, the experimental data indicate that the effect of trees, buildings and so on have a secondary influence on the decay of the electric field with distance, the dominant one is the propagation loss over an imperfect ground. Contemporary propagation models do not acknowledge this fact. Outside the cellular radius of a few kilometers the path loss appears to be 12 dB/octave or 40 dB/decade of distance. In a companion paper it will be demonstrated that the values for the path loss can be explained from an analytical standpoint without taking recourse to statistics which involves a lot of assumptions on the functional variation of the variables of interest [2].