《RADIO ENGINEERING SECOND EDITION》求取 ⇩

ⅠHow Broadcasting is Done8

1．Requirements to be met in a Broadcast Transmission8

2．Transmission from Studio to Aerial8

3．Reasons for Use of High-Frequency Currents in Aerial10

4．Modulation10

5．Production of Sidebands by Modulation12

6．Radiation13

7．Relation between Frequency and Wavelength14

8．Frequency Nomenclature and Tolerances15

8．1．Atlantic City Frequency Tolerances15

9．Allocation of Wavelength and Frequency Bands for Broadcasting15

10．B．B．C．Call Signs,Frequencies and Wavelengths used in Short-wave Services16

11．Chain of Apparatus involved in a Broadcast Transmission19

12．Limiting Amplifier or Limiter22

ⅡElectrical Effects and Units24

1．The Magnetic Field25

2．Electrons,Dielectrics(Insulators),and Conductors26

2．1．Convention for Direction of Current27

3．Electromotive Force=e．m．f．27

4．The Electric Field28

5．Potential Difference28

6．Field Strength=Strength of Electric Field29

7．Definition of the Volt29

8．Current and Magnetic Effect of a Current29

9．Definition of the Ampere,the Practical Unit of Current30

10．Electrical Quantity:Definition of the Coulomb,the Practical Unit of Electrical Quantity31

11．Linkage:E．M．F．induced by Change of Linkage31

12．Resistance:Definition of the Ohm,the Practical Unit of Resistance31

13．Wire Resistance32

13．1．Skin Effect36

13．2．The R．M．A．Colour Code43

14．Definition of the Watt,the Unit of Electrical Power44

15．Mechanical Equivalent of the W45

16．Thermal Equivalent of the W45

17．Inductance:Definition of the Henry,the Unit of Inductance45

17．1．Inductance of Air-Core Coils46

17．2．Best Coil Form49

17．3．The Coil Figure of Merit:Q49

17．4．Methods of Reducing the Effective Resistance of Coils50

17．5．Self-Capacity of Coils50

17．6．Miscellaneous Inductance Formulae51

18．Magneto-motive Force=m．m．f．57

19．Reluctance of a Magnetic Circuit57

20．Permeability58

21．Capacity(Capacitance)58

22．Definition of the Practical Units of Capacity:the Farad,the Microfarad and the Micro-Microfarad59

22．1．Capacity Formulae59

23．Dielectric Constant60

23．1．Dielectric Constants61

23．2．Characteristics of Shell KB30 Transformer Oil61

24．Condensers61

24．1．Electrolytic Condensers62

25．Interaction between Magnetic Field and Current64

26．Lenz＇s Law and its Inverse65

27．Thermo-electric Effect65

28．Contact Potentials65

29．＂Dry＂and＂Wet＂Contacts65

30．Conversion Tables between Units66

31．Voltage Breakdown in Air76

31．1．Use of Spark Gaps as Voltage Limiters78

32．Other Physical Effects78

33．Mass and Weight79

34．Density and Specific Gravity79

35．Relations between Different Kinds of Energy80

36．Current-carrying Capacity of Conductors82

99．Numerical Examples84

ⅢThe Sine Wave and Vectors89

1．Trigonometrical Definitions89

2．Form of a Sine Wave92

3．Representation of Sine Waves by Vectors95

3．1．Addition of Vectors97

3．2．Derivation of Formulae for the Addition of Sine Waves and Vectors98

4．The Complex Plane100

5．Representation of the Angle of a Vector by ejθ104

6．Negative Vectors and Negative Angles105

7．Cosine Waves106

8．Solution of Triangles106

99．Numerical Examples107

ⅣRelations between Steady Voltages and Direct Currents110

1．Resistance and Conductivity110

2．Internal Electromotive Force in Generators110

3．Resistances in Series111

4．Resistances in Parallel112

5．Back Electromotive Force113

6．Power in Direct-Current Circuits113

6．1．Energy Stored in a Condenser114

6．2．Energy Stored in an Inductance114

7．Time Constants115

7．1．Resistance Capacity Circuits115

7．2．Resistance Inductance Circuits116

99．Numerical Examples118

ⅤRelations between Alternating Voltages and Currents120

1．Relation between Voltage across a Resistance,and Current120

2．Relation between Voltage across an Inductance,and Current120

3．Relation between Voltage across a Capacity,and Current122

4．Impedance and Complex Quantities123

5．Addition and Subtraction of Complex Quantities127

6．Multiplication of Complex Quantities128

7．Division of Complex Quantities128

8．Impedances in Series129

9．Condensers in Series129

10．Impedances in Parallel130

11．Admittance133

12．Vector and Scalar Notation and Mixed Notation133

13．The Principle of Superposition135

14．Reciprocity Theorem136

15．Thévenin＇s Theorem136

16．Parallel Representation of Impedances137

17．Reactance Chart140

18．Kirchhoff＇s Laws142

19．Impedance Potentiometers145

99．Numerical Examples147

ⅥSelective Circuits:Resonance and Tuning154

1．Series Resonance155

2．Parallel Resonance157

2．1．Condition at Parallel Resonance158

2．11．Relation between fr and fo160

2．2．Conditions for Maximum Impedance of a Parallel Resonant Circuit160

2．3．Natural Frequency161

2．4．Practical Application of Parallel Resonant Circuit161

2．5．Selectivity and Response162

2．6．Choice of Values of Elements in Tuned Circuits164

3．Rejector and Acceptor Circuits165

4．Other Types of Selective Circuit166

5．Decay Factor,Decay Index,Decrement,Q and Natural Frequency of a Circuit166

5．1．Definitions167

5．2．Measurement of Q,Decrement,Decay Factor and Decay Index of a Coil167

99．Numerical Examples172

ⅦPower in Alternating Current Circuits177

1．Power delivered to a Resistance by a Sinusoidal Alternating Current177

2．R．M．S．Sum of a Number of Alternating Currents or Voltages177

3．Power in Circuits containing both Reactance and Resistance178

4．Power Factor179

5．Power Ratios:The Decibel179

6．Level and Volume182

6．1．Level of Tone182

6．2．The Nature of Programme and Noise183

6．3．Volume of Programme and Noise184

6．4．Applications186

7．Levels in Speech and Music Circuits187

8．Level of Line-Up Tone and Use of Line-Up Tone187

9．Impedance Matching188

10．Reflection Loss190

10．1．Transition Loss191

11．Use of Impedance Transforming Circuits to avoid Reflection Loss192

12．Insertion Loss and Gain195

13．Coupled Circuits and Coupling Factor196

13．1．Leakage Flux196

13．2．Coupling Factor197

13．3．Mutual Inductance198

13．4．Leakage Inductance198

13．5．Impedance looking into Primary of Coupled Circuit198

13．6．Mutual Impedance199

13．7．Adjustment of Coupling199

14．Design of Impedance Matching or Coupling Circuits201

14．1．kVA to Kilowatts Ratio201

14．2．Current per Kilowatt through Inductances202

14．3．Design of Coupling Circuits in which the kVA/kW Ratio does not have to be considered204

14．31．Broad-Band Amplifiers211

14．32．Tuned Amplifiers(Narrow-Band Amplifiers)213

14．4．Method of Adjusting and Tuning Coupled Circuits214

14．5．Design of Coupling Circuits in which the kVA/kW Ratio has to be taken into Account215

14．6．Design of Coupling Circuits without the use of Charts217

15．Effective Inductance of two Inductances L1 and L2 with Mutual Coupling M between them218

16．Measurement of Coupling Factor k of two Inductances220

17．Attenuators220

17．1．Attenuators in which Z1 and Z2 are unequal:Dissymmetrical T and π Networks224

99．Numerical Examples225

ⅧHarmonic Analysis and Dietortion230

1．Periodic Waves230

1．1．Spectra of Amplitude Modulated Waves239

2．Spectrum of Speech and Music243

3．Distortion248

3．1．Response Distortion:Response Characteristics248

3．11．Permissible Deviation of Response Characteristics in Audio-Frequency Circuits250

3．2．Phase Distortion in Audio-Frequency Circuits252

3．3．Non-Linear Distortion258

4．Effects of Distortion in Radio-Frequency Circuits259

4．1．Measurement of Distortion in Radio-Frequency Circuits260

4．2．Effect of Attenuation and Phase Shift of Sidebands260

ⅨThermionic Valves264

1．The Diode264

2．The Triode266

3．Anode Impedance=Ro267

4．Load Line269

4．1．Use of the Load Line271

4．2．Grid Bias and Cut-Off273

5．Voltage Amplification273

6．Voltage Amplification Factor of Valve=μ275

7．Mutual Conductance of Valve=gm276

7．1．Relation between gm,μ and Ro276

8．Power Amplification277

9．Non-Linearity277

10．Capacities in a Triode278

11．The Screen-Grid Valve or Tetrode279

11．1．Secondary Emission279

12．The Pentode280

13．Mixers282

13．1．Hexode282

13．2．Heptode283

13．3．Octode283

14．Variable μ Valves283

15．Composite Valves284

16．Short-Wave Valves284

17．Anode Dissipation285

17．1．Air-Cooled Anodes285

17．2．Water-Cooled Anodes285

17．3．Cooling of Seals286

18．Operation and Maintenance of Thermionic Valves286

18．1．Procedure for Applying Supplies to a Valve286

18．2．Marked Volts(Filament Volts)287

18．3．New Valves(Introduction into service of)289

18．4．Gas Test289

18．41．Pirani Test290

18．5．Service Test on Spare Valves290

18．6．Emission Tests290

18．61．Total Emission Test290

18．62．Suppressed Emission Test290

18．63．Emission Tests on Medium-Size Valves and Small Valves291

18．7．Valve Cooling Water291

19．Total Emission,Peak Emission,Peak Anode Current,and Cathode Emission291

20．Grid Input Impedance of Valves293

21．Transmitting Valves294

ⅩAmplifiers295

1．Class A Amplifiers295

1．1．Phase Relation between Grid Volts and Anode Volts298

2．Resistance-Coupled Amplifier299

3．Choke-Coupled Amplifier300

4．Load Line for Resistance-Coupled Amplifier300

5．Load Line for Choke-Coupled Amplifier301

6．Transformer-Coupled Amplifier302

7．Automatic Grid Bias304

8．Push-Pull Connection of Valves305

9．Class B Amplifiers308

10．Design of Push-Pull Output Transformers for Class A and Class B Amplifiers309

11．Power Output and Efficiency of Class B Amplifiers310

11．1．Comparison of Power Output of Class A and Class B Amplifiers:Adjustment of Load Line for Maximum Output312

12．Variation of Power Consumption of Anode Circuit of Amplifier as Grid Drive Varies318

13．Variation of Anode Dissipation as Grid Drive Varies319

14．Theoretical Optimum Value of Anode Load Impedance319

15．Tuned Amplifiers321

16．Definitions of A,B,and C Tuned Amplifiers323

17．Circuit Arrangement of Tuned Amplifiers324

18．Make-up Current326

19．Neutralization of Anode-Grid Capacity of Valves326

19．1．Circuits which Provide Stability and Freedom from Feedback327

19．11．The Split Anode Neut Circuit327

19．12．Push-Pull Neut Circuit329

19．13．Inductance-Capacity Potentiometer Neut Circuit331

19．2．The Split-Grid Neut Circuit332

19．3．Neut Circuit in High-Power Tetrodes334

20．Adjustment of Neut Condensers335

20．1．Method Ⅰ．Direct Adjustment of Loss335

20．2．Method Ⅱ．Grid Current Method336

20．3．Method Ⅲ．Anode-Current Grid-Current Method337

20．4．Method Ⅳ．Anode Current Method338

20．5．Method of Neuting to Use338

20．6．Neuting of Short-Wave Amplifiers340

21．Design of Class A Tuned Amplifiers340

22．Class B and C Tuned Amplifiers340

22．1．Definition of Angle of Current Flow342

22．2．Relation between Angle of Current Flow and Anode Current Ratios:Peak Fundamental to Peak,Peak Fundamental to Mean,and Mean to Peak Ratio342

22．3．Relation between Load Line in Class C Amplifier and Impedance Facing Anode345

23．Power Output of a Class C Tuned Amplifier346

23．1．Power Output of a Class B Amplifier347

24．Anode Efficiency of a Class C Tuned Amplifier347

24．1．Anode Efficiency of a Class B Amplifier(See also X:30)347

24．2．Anode Efficiency of a Class B Tuned Amplifier Transmitting a Modulated Wave347

25．The Angle of Current Flow348

25．1．Determination of θ,the Angle of Current Flow348

25．2．Effect of Changing the Angle of Current Flow,θ351

25．21．Comparison of Performance of Class B and Class C Tuned Amplifiers(Relation between Angle of Current Flow,Grid Peak Volts,Effective Grid Peak Volts,Working Bias and Cut-off Bias)353

25．22．Detailed Examination of the Effect of Changing the Angle of Current Flow in a Class C Amplifier357

25．3．Choice of Angle of Current Flow359

25．4．Determination of Grid Bias and Grid Drive to Produce a Required Angle of Current Flow360

26．Practical Design of a Class C Amplifier361

26．1．Grid Loading of Linear Class B Amplifiers364

26．2．Choice of Valve for use in Class C Amplifiers365

26．3．Determination of Working Conditions of a Class C Amplifier which is not driven into Anode Limitation368

26．31．Determination of Anode Load Impedance369

27．Anode Limitation370

27．1．Asymptote377

28．Variation of Anode Current as Anode Circuit is Tuned377

29．Variation of Grid Current as Anode Circuit is Tuned378

30．Working Conditions of Class B Tuned Amplifier taking into account No-Drive Standing Feed378

31．Examination of a Practical Tuned Amplifier381

32．Design of Output Coupling Circuit for a Push-Pull Class B or C Tuned Amplifier384

33．Practical Measurement of Valve Anode Efficiency385

33．1．Measurement of Valve Anode Eficiency by Temperature Rise of Anode Cooling Water386

34．Anode Peak Volts and Anode Peak Current in a Modulated Amplifier or other Amplifier driven into Anode Limitation388

35．Inverted Amplifier389

35．1．Necessity for Modulating the Drive Stage392

35．2．Summary393

35．3．Circuit of Practical Inverted Amplifier and Driver393

35．4．Design of Inverted Amplifier and Driver Stage394

35．5．Relations in a Class A Inverted Amplifier397

35．6．Relations in a Class C Inverted Amplifier398

35．61．Power Output from an Inverted Amplifier399

35．62．Power Amplification of an Inverted Amplifier399

35．63．Percentage Modulation Realizable with an Inverted Amplifier400

35．7．Operation and Adjustment of Inverted Amplifiers400

36．Short-Wave Amplifiers401

37．Valve Anode Efficiency,Valve Anode Circuit Efficiency and Output Efficiency of an Amplifying Stage401

38．Grid Dissipation in a Class C Amplifier403

39．D．C．Amplifiers404

99．Examples407

ⅪOscillators414

1．Early Views on Oscillators414

1．1．Standard Oscillator Circuits418

1．2．Frequency Stabilization of Oscillators419

2．Present Views on Oscillators423

2．1．Series Resonance Osciliator423

3．Design and Performance of a Practical Oscillator427

4．Crystal Oscillators430

4．1．The AT Cut Plate433

4．2．Frequency Stability of Crystal Oscillators using AT Cut Plates435

4．3．Crystal Oscillator Circuits435

4．31．Series Resonance Type435

4．32．The Meacham Crystal Bridge Oscillator Circuit436

4．33．Miller Circuit Crystal Oscillator437

4．4．Crystal Ovens439

5．Dynatron Oscillators441

6．The Two Types of Negative Resistance442

7．Resonant Line Oscillators442

8．Electron-Coupled Oscillator445

9．Beat Oscillators446

9．1．Intermodulation of Two Frequencies in a Square Law Modulator446

9．2．Frequency Stability of Beat Oscillators448

10．Resistance-Capacity Oscillator449

11．Freak Oscillations451

12．Parasitic Oscillations452

12．1．Detection of Parasitic Oscillations452

12．2．Causes of Parasitic Oscillation—particularly affecting Audio-Frequency Amplifiers453

12．3．Causes of Parasitic Oscillations—particularly affecting Radio-Frequency Amplifiers456

12．4．Location of Parasitic Oscillations461

12．41．Inter-stage Oscillations463

12．42．Oscillations involving Input and output Lines463

12．43．Oscillations Internal to Stage464

12．44．Oscillations in R．F．Amplifiers464

13．Stability Tests on Transmitters465

ⅫDrive Equipment467

1．Definition of Drive Equipment467

2．Cairo Requirements on Frequency Stability of Transmitters467

3．Synchronized Operation of Transmitters on the same Wavelength467

4．The Beat Indicator469

4．1．Cathode Ray Tube Indicator471

5．Methods of Frequency Checking and Adjustment in Synchronized Groups471

5．1．Frequency Checking by Radio471

5．2．Frequency Checking By Line472

6．Frequency Dividers473

6．1．Locked Oscillators473

6．2．Multivibrators473

6．21．Single-Circuit Divider477

6．211．Method of Operation478

6．22．Locking of Multivibrators480

6．221．Locking Condition for Division by an Odd Number481

6．222．Locking Condition for Division by an Even Number482

6．223．Adjustment of Relative Lengths of the Two Half-Periods of a Multivibrator483

6．3．Modulator Dividers484

7．Frequency Multipliers489

7．1．Harmonic-Generator Multiplier490

7．2．Harmonic Generators for Multiplying by Odd Numbers491

7．3．Harmonic Generators for Multiplying by Even Numbers491

7．4．Limitation on Multiplication Factor493

8．Vernier Scales496

ⅩⅢModulators and Modulation498

1．Different Types of Modulation498

2．Heising or Choke Modulation501

3．Class B Modulation503

3．1．Temporary Conversion of Class B Modulator to Class A Operation505

3．2．Series Modulation505

3．3．Design of a Series Modulator508

4．Principle of a Modulated Amplifier509

4．1．Upward and Downward Modulation in Modulated Amplifiers516

4．2．Initial Adjustment of a Modulated Amplifier517

4．3．Simple Procedure for adjusting a Modulated Amplifier522

4．4．Power Handling Capacity525

5．Diode Modulator526

6．Class C Grid Modulator528

7．Anode Bend Modulator532

8．Suppressor Grid Class C Modulator535

8．1．Anode Modulation of Pentode(Suppressor Grid Modulator)538

9．Conversion to 100％ Modulation538

10．Push-Pull or Balanced Modulators539

10．1．Double Balanced Modulator541

10．2．Use of Tetrodes in Modulated Amplifier544

11．Spectrum of Modulated Wave544

11．1．Amplitude-Modulated Wave544

11．2．Phase-Modulated Wave548

11．3．Frequency-Modulated Wave549

11．4．Modulation by a Band of Frequencies550

11．5．Numerical Determination of Spectra of Frequency-Modulated and Phase-Modulated Waves552

11．6．Frequency Range occupied by a Frequency-Modulated or a Phase-Modulated Wave557

11．7．Reduction of Noise Level at the Receiver in a Frequency-Modulation System558

11．71．Behaviour of the Limiter559

11．72．Demonstration that the Effective Noise Level in the Receiver is inversely proportional to the Amplitude of Carrier Frequency Swing559

11．73．Comparison of Speech-to-Noise Ratios in Amplitude-Modulated and Frequency-Modulated Systems561

11．8．False Phase Modulation563

12．Heising Modulation Formulae564

ⅩⅣTransmitter Types568

1．Trend of Development568

2．Low-Power Modulation568

3．Series Modulation569

4．Class B Modulation569

5．The Chireix System569

6．The Doherty System572

6．1．The Improved Doherty System576

6．11．Design of a Doherty Amplifier576

6．2．Grid-Modulated Doherty Amplifier578

6．21．Design of Grid-Modulated Doherty Amplifier579

6．22．Example of a Practical Circuit586

6．23．Representation of Voltages and Currents in a Grid-Modulated Doherty Amplifier591

7．The Fortescue System594

8．The Floating Carrier System595

9．Efficiencies of Output Stages of Different Systems597

9．1．Class A High-Power Modulation(includes Heising and Series Modulation)597

9．2．Class B High-Power Modulation598

9．3．Low-Power Modulation599

9．4．The Chireix System599

9．5．The Doherty System600

9．51．The Improved Doherty System601

9．6．The Fortescue System602

10．Comparison of Different Systems603

11．Observed Overall Efficiency of Transmitters605

12．H．T．Smoothing Circuits607

12．1．Class B System608

ⅩⅤOperation and Maintenance of Transmitters613

1．Starting UP a Transmitter613

1．1．Putting a New Valve into Service614

2．Shutting Down a Transmitter614

3．Shutting Down in Extreme Emergency615

4．Line-up of Transmitter for Modulation615

4．1．Old-Type Programme Meter615

4．2．Peak Programme Meter616

5．Running Adjustments616

6．Installation of Spare Valves616

7．Changing Wave617

8．Reducing Power Output of a Transmitter619

8．1．Reducing the Number of Valves620

8．2．Reducing Coupling621

8．3．Reduction of H．T．622

9．Operation of Transmitters in Parallel on the Same Wavelength622

10．Prevention and Clearance of Faults624

10．1．Maintenance Routines on Valves624

10．2．Maintenance Routines on Transmitters624

10．3．Clearing Faults625

10．31．Fault Analysis626

11．Flashover626

11．1．Procedure when a Flashover Occurs626

11．2．Cause of Flashover626

ⅩⅥFeeders,Aerial-Coupling Cirouits and Aerials628

1．The Behaviour of Feeders629

1．1．Characteristic Impedance=Zo632

1．2．Loop Inductance,Capacity per Unit Length and Characteristic Impedances of Three Types of Feeder632

1．3．Propagation Constant,Attenuation Constant and Phase Shift Constant．Relations between Voltages and Currents in Properly Terminated Feeder and Sending-End Voltages and Currents635

1．4．Relation between Wavelength λ and Phase Constant α638

1．5．Phase Velocity of a Progressive Wave．Relations between Phase Velocity,Wavelength and Frequency638

1．6．Attenuation of Feeders639

1．7．Standing Waves640

1．71．Instantaneous Voltages in an Open-Circuited Line640

1．72．Instantaneous Currents in an Open-Circuited Line643

1．73．Instantaneous Voltages and Currents in a Short-Circuited Line643

1．74．Derivation of Formulae for Voltages and Currents in Open-Circuited Line and Sending-End Impedance644

1．75．Voltages and Currents in Short-Circuited and Sending-End Impedance645

1．8．Line terminted in an Impedance not equal to its Characteristic Impedance646

1．81．Determination of Ratio between Incident and Reflected Currents and Voltages646

1．82．Sending-End Impedance of Line of Characteristic Impedance Z0,terminated in an Impedance Z647

1．9．Determination of Wavelength in a Feeder or Transmission Line649

1．10．Nodes and Antinodes in a line terminated in a Mismatched Load-Taking Power649

2．Circle Diagrams650

2．1．Method of Entering Parallel Represented Impedances652

3．Impedance Matching in Feeders656

3．1．Magnitude of Standing Waves656

3．11．Standing Wave Ratio657

3．12．Use of Circle Diagram to determine the Magnitude of the Standing Wave Ratio in a Feeder658

3．2．Determination of Terminal Impedance from the Currents at Nodes and Antinodes659

3．3．Impedance Matching in Short-Wave Feeders．Use of Tails for Impedance Matching659

3．4．Impedance Matching by Use of Inserted Length of Feeder of Different Inpedance from the Main Feeder662

4．The Quarter-Wave Line666

5．Feeders as Filters668

5．1．The Tapped Quarter-Wave Line670

6．Conductor Sizes and Power-Carrying Capacity of Feeders671

7．Short-Wave Transmitting Aerials672

7．1．Arrangement and Method of Designation of Short-Wave Arrays675

7．11．Performance of Arrays676

7．111．Power-Density Diagrams676

7．112．Calibration of Power-Density Diagrams687

7．2．Slewing of Arrays688

7．3．Reflectors688

7．4．The Impedance Presented by a Half-Wave Dipole690

7．41．Centre-Fed Dipole690

7．42．Shunt-Fed Dipole691

7．43．End-Fed Dipole691

7．5．Impedance of an Array692

7．6．Size of Conductor used in Dipole Arrays692

7．7．Kraus Aerial693

7．8．Lengths of Half-Wave Dipoles693

8．Impedance Matching in Medium and Long-Wave Feeders695

8．1．Essential Points to be observed in Adjustment of Aerial Circuits695

8．2．Aerial-Coupling Unit696

8．3．Equivalence of Series and Parallel Impedances697

8．4．L Networks for Use as Impedance Transforming Sections698

8．5．Method of Setting Up Aerial Coupling Circuits700

8．51．Choice of Form of Circuit on Secondary Side of the Coupling Unit702

8．6．Matching of Low Impedances704

9．Insertion of Rejector Circuits for the Prevention of＂Throw-in＂705

10．Operation of Two Transmitters on Different Wavelengths into a Single Aerial709

11．Losses in Aerial Tuning Huts709

12．Impedance Matching in Long-Wave Aerial Circuits710

12．1．Principles of Design in Long-Wave Aerial Circuits of B．B．C．Transmitter at Droitwich715

12．11．Simulation of Reactance Curve by Series Resonant Circuit716

12．12．Neutralization of Aerial Reactance717

12．13．Power Factor Correction at Two Sideband Frequencies718

12．14．Calculation of Circuit Impedances720

12．15．Frequency Response726

12．16．Analysis of Circuit used at Droitwich and Method of Design of Component Networks to Build up Overall Required Phase Shift727

13．Relations between Inductance and Capacity per Metre,Characteristic Impedance and Phase Velocity731

13．1．Inductance of Straight Vertical Wire732

13．2．Value of Condenser required to Neutralize Reactance of Grid Lead733

13．3．Elimination of Phase Shift in Grid Lead735

13．4．Neutralization of Reactance of Earth Lead737

14．Stress Diagrams in Aerial Arrays738

14．1．Vector Conventions739

14．2．Force and Space Diagrams740

14．3．Bow＇s Notation741

14．4．Catenary741

14．5．Triatic with Single Load744

14．6．Multi-loaded Triatic747

14．7．Curtain Array750

14．8．Windage and Ice753

14．9．Factors of Safety754

Index757