The Principles Underlying Radio Communication

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Batcheller Collection.
 

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Contents

The potentiometer
67
The Wheatstone bridge
69
Heat and power losses
70
F CAPACITANCE 29 Dielectric current
71
Condensers
72
38
73
Dielectric properties
74
Types of condensers
76
Electric field intensity
77
Energy stored in a condenser
78
42
79
G MAGNETISM 36 Natural magnets
81
The magnetic field
82
Magnetic flux and flux density
83
The magnetic field about a current
84
Magnetic induction and permeability
85
The force on a current in a magnetic field
86
H INDUCTANCE 44 The linking of circuits with lines of magnetic flux
87
Induced electromotive force
88
Characteristics of terminal voltage
89
Self inductance
90
Mutual inductance
91
Energy relations in inductive circuits
92
ALTERNATING CURRENT 49 Reactance
93
17
94
Average and effective values of alternating current
95
Circuit with resistance only
97
Alternating current in a circuit containing inductance only
98
Circuit containing inductance and resistance
100
Charging of a condenser in an alternating current circuit
102
22
103
Circuit containing capacitance inductance and resist ance
104
The alternating current transformer
105
J MEASURING INSTRUMENTs b9 Hot wire instruments
106
Magnetic instruments
108
DynamoElectric Machinery 61 Generators and motors
115
Direction of emf
117
Multipolar magnets
118
Coilwound armature
119
Concentrated and distributed windings
121
Field excitation
124
Other forms of alternator
125
Equations for frequency and emf
131
Dependence of driving power on current
132
Losses
133
Rating Name plate data
135
Efficiency
136
Armature impedance and armature reaction I37 83 Effect of power factor on regulation
137
Effect of speed on regulation
138
Effect of varying speed g D SPECIAL ALTERNATORs For RADIO Us Es 93 Audio frequency and radio frequency
149
Audio frequency generators
150
Radio frequency generators
161
E MOTORs 96 Uses of d c and a c motors 97 D c shunt motor
164
Coupling
165
Damping and decrement
166
series motor
172
Other d c motors 100 Combination a c and d c motors 101 Induction motors
173
F MOTORGENERATORS AND DYNAMOTORs 102 Motorgenerators
175
Rotary converters 104 Dynamotors
177
Double current generators
178
Common troubles
179
Radio Circuits A SIMPLE RADIO CIRCUITs 107 The simplicity of radio theory
182
The simple series circuit
183
Series resonance
185
Tuning the circuit to resonance
190
Resonance curves
191
The wavemeter
193
Forced oscillations
216
Free oscillations of coupled circuits with small damping
218
Impulse excitation Quenched gap
221
Electromagnetic Waves A WAVE MOTION 124 Three ways of transmitting energy
223
Wave trains continuous and discontinuous
224
B PROPAGATION OF WAVEs 127 Waves propagated by elastic properties of medium
225
Modification of waves in free space near earth
226
Static
228
Magnetic field produced by moving lines of electric dis placement
229
Mechanism of radiation from a simple oscillator
230
Action in receiving
232
Statement of formulas
234
Examples of use
235
E DEVICE FOR RADIATING AND RECEIVING WAVEs Page 137 Description of the antenna
236
Different types
238
Current and voltage distribution in an antenna
239
Action of the ground Counterpoises
240
F ANTENNA CHARACTERISTICs
241
Capacitance
242
Inductance
243
Wave length and its measurement
244
Harmonics of wave length
246
G ANTENNA CONSTRUCTION 147 Towers and supports
247
Antenna switch Conductors
248
Grounds and counterpoises
249
Directional curve
250
Constants of closed coil aerials
251
Apparatus for Transmission and Reception Exclusive of Wacuum Tubes A APPARATUS FOR DAMPED WAVE TRANSMIssion 153 Function of tr...
254
Transmitting condensers
257
Simple induction coil set
262
15S Operation of induction coils from power lines
263
Portable transmitting sets
264
Simple connections for the production of electric waves
265
Inductively coupled transmitting set
268
Direct coupled transmitting set
270
Comparison of coupled and plain antenna sets
271
Tuning and resonance
272
Adjustment of a typical set for sharp wave and radiation
277
Efficiency of the set 170
278
171
283
General principles
290
Typical circuits for reception of damped waves
293
Typical circuits for reception of undamped waves
299
Crystal detectors
302
Telephone receivers
305
Receiving coils and condensers
306
Measurement of received current
310
Wacuum Tubes in Radio Communication 183 Introduction A ELECTRON FLOW IN WACUUM TUBEs 184 Current in a twoelectrode tube 3 1
311
Actual forms of twoelectrode tubes
314
Effect of grid
317
Characteristic curve
319
Practical forms of threeelectrode tubes
320
Simple detector circuit and explanation of its action
322
Effect of incoming signals upon the plate current
325
THE WACUUM TUBE As AN AMPLIFIER 193 General principle
326
Elementary theory of amplification
328
Audio frequency amplification 196 Regenerative amplification
330
Vacuum tube amplifier with crystal detector
331
Conditions for oscillation
332
Practical considerations in using vacuum tubes as oscil lation generators
334
Tubes suitable for developing considerable power
335
Heterodyne and autodyne receiving by vacuum tubes
336
E RADiO TELEPHONY 202 Voice modulation of radio currents by vacuum tubes
337
Other methods of voice modulation
339
SUGGESTED LIST OF LABORATORY ExPERIMENTs
342
UNITs
350
SYMBOLS 354

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Page 353 - The unit of quantity shall be what is known as the international coulomb, which is the quantity of electricity transferred by a current of one international ampere in one second. Fifth. The unit of capacity shall be what is known as the international farad, which is the capacity of a condenser charged to a potential of one international volt by one international coulomb of electricity.
Page 84 - Grasp the wire in the right hand, with the thumb pointing in the direction of the current. The fingers will curl around the wire in the direction of Conductor the magnetic field".
Page 250 - ... zero when the plane of the coil is at right angles to the direction of the lines of force, and therefore the induced electromotive force is here zero.
Page 352 - Ampere, which is one-tenth of the unit of current of the CGS system of electromagnetic units and which is represented sufficiently well for practical use by the unvarying current which, when passed through a solution of nitrate of silver in water, in accordance with a certain specification, deposits silver at the rate of 0.001118 of a gramme per second.
Page 20 - This is analogous to the kind of flow which would be produced if, instead of being acted on by a pump, the water were agitated by a paddle which moved back and forth rapidly over a short distance, without traveling beyond certain limits. Under this impetus the water no sooner gets up speed in one direction than it is compelled to slow up and then gather speed in the opposite direction, and so on over and over again. The water simply surges, first in one direction, and then in the other, so that a...
Page 67 - The currents in the two branches are inversely proportional to the resistances of their respective paths. This relation is called the "shunt law.
Page 65 - Exercise.— Assume a battery of two dry cells in series, each cell having an emf. of 1.5 volts and an internal resistance of 0.3 ohm. Each battery then has an emf. of 3 volts and an internal resistance of 0.6 ohm. Suppose that the external resistance in the circuit is 0.2 ohm, and that a current of 6 amp. is to be established. Solution. — If we try one battery, Ohm's law gives = 3. T,"> amp. 0.2+0.6...
Page 202 - The potential difference of the plates now acts in such a direction as to oppose the flow of the current, which decreases continually as the potential difference of the plates rises.
Page 92 - ... inductance is often used to transfer power from one circuit to another when there is no conducting path between them. 48. Energy Relations in Inductive Circuits. — In mechanics it is well known that a piece of matter cannot set itself in motion and that energy must be supplied from outside. So in the electric circuit, a current cannot set itself in motion, and energy must be supplied by some form of generator (source of emf.). It has already been explained how a magnetic field arises about...
Page 330 - Ci is charged in the usual way, but accumulates a charge which is proportional not to the original signal strength but to the final amplitude of the oscillations in the grid circuit. The result is a current in the telephone much greater than would have been obtained from the original oscillations in the circuit.

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