Introduction A transmission line is a system of conductors connecting one point to another and along which electromagnetic energy can be sent. Thus telephone lines and power distribution lines are typical examples of transmission lines; in electronics, however, the term usually implies a line used for the transmission of radio-frequency (r.f.) energy such as that […]
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Introduction An attenuator is a device for introducing a specified loss between a signal source and a matched load without upsetting the impedance relationship necessary for matching. The loss introduced is constant irrespective of frequency; since reactive elements (L or C) vary with frequency, it follows that ideal attenuators are networks containing pure resistances. A […]
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Introduction to Modulation The transmission of information such as speech, music and data over long distances requires the use of a carrier channel. It is common practise to ‘carry’ different communications, called signals, at different frequencies to stop one signal from interfering with another. A signal can be shifted bodily from its original band to […]
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Introduction A filter is a network designed to pass signals having frequencies within certain bands (called passbands) with little attenuation, but greatly attenuates signals within other bands (called attenuation bands or stopbands). A filter is frequency sensitive and is thus composed of reactive elements. Since certain frequencies are to be passed with minimal loss, ideally […]
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Introduction Electric fields, magnetic fields and conduction fields (i.e. a region in which an electric current flows) are analogous, i.e. they all exhibit similar characteristics. Thus they may all be analysed by similar processes. In the following the electric field is analysed. Figure 79.1 shows two parallel plates A and B. Let the potential on […]
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Electric Fields, Capacitance and Permittivity Any region in which an electric charge experiences a force is called an electrostatic field. Electric fields, Coulombs law, capacitance and permittivity are discussed in chapter 44 — refer back to page 233. Summarising the main formulae: Polarisation When a dielectric is placed between charged plates, the capacitance of the […]
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Introduction Many practical waveforms can be represented by simple mathematical expressions, and, by using Fourier series, the magnitude of their harmonic components determined. For waveforms not in this category, analysis may be achieved by numerical methods. Harmonic analysis is the process of resolving a periodic, non-sinusoidal quantity into a series of sinusoidal components of ascending […]
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Maximum Power Transfer Theorems A network that contains linear impedances and one or more voltage or current sources can be reduced to a The´venin equivalent circuit as shown in chapter 73. When a load is connected to the terminals of this equivalent circuit, power is transferred from the source to the load. A Thevenin equivalent […]
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Introduction By using Kirchhoff’s laws, mesh-current analysis, nodal analysis or the super- position theorem, currents and voltages in many network can be determined as shown in chapters 70 to 72. Thevenin’s and Norton’s theorems, introduced in chapter 73, provide an alternative method of solving networks and often with considerably reduced numerical calculations. Also, these latter […]
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Introduction Many of the networks analysed in Chapters 70 to 72 using Kirchhoff’s laws, mesh-current and nodal analysis and the superposition theorem can be analysed more quickly and easily by using The´venin’s or Norton’s theorems. Each of these theorems involves replacing what may be a complicated network of sources and linear impedances with a simple […]
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