Text 1A Electromagnetic waves and antenna basics Radio signals are a form of electromagnetic wave, and as they are the way in which radio signals travel, they have a major bearing on RF antennas themselves and RF antenna design. <...> The electric field results from the voltage changes occurring in the RF antenna which is radiating the signal, and the magnetic changes result from the current flow. <...> It is also found that the lines of force in the electric field run along the same axis as the RF antenna, but spreading out as they move away from it. <...> Similarly when an RF antenna receives a signal the magnetic changes cause a current flow, and the electric field changes cause the voltage changes on the antenna. <...> Wavelength of an electromagnetic wave The wavelength of an electromagnetic wave The second property of the electromagnetic wave is its frequency. <...> It is very easy to relate the frequency and wavelength as they are linked by the speed of light as shown: lambda = c / f where lambda = the wavelength in metres; f = frequency in Hertz; c = speed of radio waves (light) taken as 300 000 000 metres per second for all practical purposes. <...> This is not part It is also interesting to note that close to the RF antenna there of the electromagnetic wave, but it can measurements induced into it. <...> Fortunately this inductive field falls away fairly rapidly and it is barely detectable at distances beyond about two or three wavelengths from the RF antenna. (2700) Answer the following questions. 1. <...> Text 1B Antenna polarisation Polarisation (or polarization) is an important factor for RF antennas and radio communications in general. <...> For the electromagnetic wave the polarization is effectively the plane in which the electric wave vibrates. <...> This is important when looking at antennas because they are sensitive to polarisation, and generally only receive or transmit a signal with a particular polarization (Fig. 2). <...> So a vertical antenna (i.e. one with vertical elements) will receive vertically polarised signals best and similarly a horizontal antenna will receive horizontally polarised signals. <...> It is reduced by a factor of cosine of the angle between the polarisation of the RF antenna and the signal. <...> Accordingly the polarisation of the antennas located in free space is <...>
Обучение_чтению_литературы_на_английском_языке_по_специальности_“Радиоэлектронные_системы_и_устройства”.pdf
УДК 802.0
ББК 81.2 Англ-923
С21
Рецензент И.Ф. Беликова
С21
Стасенко И.В.
Обучение чтению литературы на английском языке по
специальности «Радиоэлектронные системы и устройства» :
метод. указания / И.В. Стасенко, М.В. Куликова, И.Г. Сафарова.
— М.: Изд-во МГТУ им. Н.Э. Баумана, 2012. — 45, [3] с. : ил.
Представленный в методических указаниях учебный материал
предназначен для обучения студентов различным видам чтения.
Тексты, заимствованные из современных научных журналов, отражают
передовые достижения в области радиосвязи, перспективы
новых технологий беспроводной связи, принципы работы радиоприемников,
радиопередатчиков, мобильных телефонов и других
беспроводных устройств. Рассмотрены также различные виды антенн,
принцип их действия, их сходство и различия. Задания на
составление плана изложения текста подготавливают студентов к
более осмысленному извлечению информации из научных источников,
создают базу для развития умения писать аннотации и рефераты
к научным статьям. Грамматические упражнения позволяют
повторить грамматический материал, вызывающий наибольшие
трудности при переводе. Содержание и лексическое наполнение
грамматических упражнений также связаны с технологиями беспроводной
связи и системами коммуникации.
Для студентов третьего курса, обучающихся по специальности
«Радиоэлектронные системы и устройства».
Рекомендовано Учебно-методической комиссией НУК ФН
МГТУ им. Н.Э. Баумана.
УДК 802.0
ББК 81.2 Англ-923
© МГТУ им. Н.Э. Баумана, 2012
2
Стр.2
CONTENTS
Введение.......................................................................................................3
Lesson 1.........................................................................................................5
Text 1A. Electromagnetic waves and antenna basics ...................................5
Text 1B. Antenna polarisation ....................................................................8
Text 1C. Antenna feed impedance ............................................................12
Grammar exercise № 1.............................................................................14
Lesson 2.......................................................................................................16
Text 2A. Antenna resonance and bandwidth..............................................16
Text 2B. Antenna bandwidth ....................................................................18
Grammar exercise № 2.............................................................................20
Lesson 3.......................................................................................................23
Text 3A. Why Digital Transmission?........................................................23
Text 3B. Fidelity of reproduction and error control digital transmission.....25
Text 3C. The satellite channel...................................................................27
Grammar exercise № 3.............................................................................29
Lesson 4.......................................................................................................31
Text 4A. Adaptive antenna arrays .............................................................31
Text 4B....................................................................................................34
Text 4C. Benefits and applications of adaptive antenna arrays...................36
Grammar exercise № 4.............................................................................39
Supplementary texts......................................................................................41
Plasma antenna technology.......................................................................41
Cognitive Radio .......................................................................................43
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