WAVE PROPAGATION AND ANTENNAS (original) (raw)

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The paper discusses wave propagation in radio communications, detailing direct and sky wave propagation with emphasis on their characteristics and factors affecting performance. It explains antenna functionality, types, and polarization, relating them to effective signal transmission in various environments. Additionally, it touches upon engineering principles in antenna design and their implications for communication systems.

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Propagation of low-frequency radio waves

IEE Proceedings - Microwaves, Antennas and Propagation, 2000

kidio WRVCS a1 fi-cilucncics less tliiin nrotind 100 kl IZ can propagite to p i l l dislanccs with little uttenu;iticsn in llic cavity l'orincd by the earth and tlic ioiiosplicre. At tlicsc rrcqucncies, nitlily active propitgation niodcs c:in occiii' bctwan the transmillcr ancl rcceiver. Clxirigs in thc ionospheric conductivity or rcflcction height i nlluciice the relative pliascs aiid miplitudcs a[ tlic propagating inodcs :ind hence Ihcir vcctor sutn. Tlic pi-opagation is less siahlc at LF than :II VLF ; a d thc icccivcd ficld strcngth is moic difficult to predict. In this investigation, 1lic Wriveliop prograin has hccu cinplopd i n conj tunclion with previously irnpublisheci suniincr-tiinc ioiiosplieric: modcls LO cstiinalc thc rcceivcci licld strcrigth over ii iiumhcr of experimcnlal paths. The predictd viilucs havc been compared with h c Incasuretnents l o validalc the ionosphcric modcls mil the inclhod of calculation.

Terrestrial Propagation of 2-Gigahertz Emissions Transmitted from the Deep Space Network 70-Meter Antenna at Robledo

2002

This article presents a case study of potential interference from a 2-GHz transmitter in the Deep Space Network (DSN) station in Robledo, Spain, to the International Mobile Telecommunications (IMT)-2000 mobile receivers in the city of Madrid about 50 km away. This study has included the effect of terrain between Robledo and Madrid in evaluating the propagation modes, which include diffraction over the terrain, ducting through the atmosphere, and scattering by rain. It is a complete revision of a previous study wherein preliminary analysis of these phenomena was presented without taking the specific terrain into account. The predicted results concerning diffraction are consistent with measurements and with predictions of the Longley–Rice model. Because of attenuation by the hills, the expected power received through diffraction by a mobile receiver on ground level in Madrid is lower than the interference thresholds (−109 dBm) when the DSN antenna transmits at the normal power of 20 k...

Microwave-line-of-sight-transmission.pdf

Microwave line of sight transmission is one of several transmission media in modern commutation. Microwave information transmission faces the problem of the effect of environment, and this requires determination of operation condition and design for optimum operation this topic is approached from two stand points: the microwave planning and project implementation. Since as a microwave link is a circuit between terminals separated through a great distance, it can be considered as a type of transmission line; but unlike copper or fiber optic cables, terrestrial microwave signals are propagated through the lower atmosphere. Thus they are sensitive to terrain, atmospheric, and climatic conditions adverse to error-free reception. An important part of microwave network is to account for these conditions and provide technical corrections. For optimal operation this paper describes the operation adjustment required and the suitable design needed so as to minimize and get rid of environmental conditions that lead to optimum performance.

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