Basic NEC with Broadcast Applications addresses computer modeling of MF directional broadcast antennas and illustrates the assets and liabilities of the Numerical Electromagnetic Code (NEC). The book's "how to" approach reveals the fundamentals of NEC operation, teaches broadcast applications and shows the reader how to use NEC-2 to: model non-radiating networks, verify calculations, detune unused towers, design top-loaded and skirted antennas, minimize coding by moving and duplicating structures, and much more! Complete with CD, the book is an invaluable toolkit with software necessary for the design and analysis of broadcast antenna arrays. *Learn to use the method of moments computer programs to design and analyze MF directional antennas *CD includes a modified version of NEC-2, programs for geometry viewing and pattern plotting, as well as author-written post processing programs to convert target field ratios to base drive voltages and to verify the integrity of the NEC-2 analysis*Concepts taught in this book apply to analysis generated by NEC-2, NEC-4, MININEC and other method of moments computer programs
Author(s): J.L. Smith
Year: 2008
Language: English
Pages: 304
Front Cover......Page 1
Basic NEC with Broadcast Applications......Page 4
Copyright Page......Page 5
Contents......Page 8
Foreword......Page 14
Preface......Page 16
Acknowledgments......Page 20
About the Author......Page 22
1.2 The Directional Antenna Adjusting Process......Page 24
1.3 Local and Global Minima......Page 25
1.4 The Role of NEC-2......Page 27
1.5 Analysis Overview......Page 28
1.6 Additional NEC-2 Benefits......Page 29
1.7 Software Requirements......Page 30
2.2 The NEC-2 Engine......Page 32
2.4.1 Naming the Files......Page 34
2.4.2 Data Commands......Page 35
2.4.4 An Input File Illustration......Page 36
2.5 Reading the Output File......Page 40
2.5.3 Segmentation Data......Page 41
2.5.4 Data Commands, Frequency, Loading, and Environment Data......Page 44
2.5.6 Currents and Locations......Page 45
2.5.7 Current Moments......Page 46
2.5.9 Radiation Pattern......Page 47
2.6 Exercises......Page 49
3.1 Modeling Guidelines......Page 50
3.2.2 Modeling the Voltage Source......Page 52
3.3 Tower Configurations......Page 53
3.3.2 Four-Wire Configuration......Page 54
3.3.4 Lattice Configuration......Page 55
3.4 Viewing Tower Configuration......Page 61
3.5 Exercises......Page 62
4.1 The Coordinate System......Page 64
4.2 Array Geometry: An Example......Page 67
4.3 The Array Input File......Page 69
4.4 Exercises......Page 73
5.1 Modeling Impedance Loads......Page 74
5.2 Modeling Nonradiating Networks......Page 76
5.2.1 Typical Networks......Page 77
5.2.2 Typical Network Applications......Page 78
5.3 Modeling Transmission Lines......Page 80
5.4.1 Network Descriptions......Page 82
5.4.2 Source and Load Impedance to the Networks......Page 83
5.5 Exercises......Page 84
6.2 Direct and Induced Currents......Page 86
6.3 Current Moments......Page 89
6.4 Development Concept......Page 90
6.4.1 Unity Drive......Page 91
6.4.2 Normalized Drive......Page 92
6.4.4 Shunt Reactance and Networks......Page 94
6.5.1 Create a Unity Drive File......Page 95
6.5.2 Calculate Unity Drive Current Moments......Page 96
6.5.3 Solve for the Normalized Drive Voltages......Page 100
6.5.4 Determine the Full Power Drive Voltages......Page 101
6.6 Exercises......Page 102
7.1 Overview......Page 104
7.2 Verify the Field Ratios......Page 105
7.3 Plot Far-Field Radiation Pattern......Page 106
7.4 Detuning Unused Towers......Page 107
7.4.1 Detuning by Base Loading......Page 108
7.4.2 Detuning by Skirting......Page 112
7.5 Antenna Monitor Readings......Page 117
7.5.1 Optimum Height for Sample Loops......Page 118
7.5.2 Arbitrary Height for Sample Loops......Page 119
7.5.3 Base Current Samples......Page 120
7.5.4 Base Voltage Samples......Page 122
7.6.1 Drive Point Impedance When Using a Network......Page 123
7.7 Exercises......Page 125
8.1 Objective......Page 128
8.2 Adjusting the Model......Page 130
8.2.1 Number of Segments......Page 131
8.2.2 Tower Diameter......Page 134
8.2.3 Segment and Radius Taper......Page 137
8.2.4 Base Capacity......Page 139
8.2.5 Drive Segment Radius......Page 141
8.3 Exercise......Page 143
9.1 General Considerations......Page 144
9.2.1 Estimating the Size of the Top Hat......Page 145
9.2.2 Determining the Degree of Top Loading......Page 146
9.3 Skirted Towers......Page 149
9.4 Folded Monopole......Page 152
9.5 Exercises......Page 155
10.2 System Definition......Page 156
10.2.1 Tower Models......Page 157
10.2.2 Tower Base Drive Voltages......Page 159
10.3.1 Source Impedance of the Drive Voltage......Page 160
10.3.2 Intermediate Data......Page 163
10.3.3 Total System Bandwidth Data......Page 169
10.4 Bandwidth Conclusions......Page 171
11.2.2 Self-Impedance: Three-Tower Array......Page 172
11.2.3 Antenna Monitor Reading: Three-Tower Array......Page 174
11.2.4 Array Data: Three-Tower Array......Page 175
11.2.6 NEC-2 Input File: Three-Tower Array......Page 176
11.3.2 Self-impedance: Six-Tower Array, Day Pattern......Page 177
11.3.3 Antenna Monitor Reading: Six-Tower Array, Day Pattern......Page 178
11.3.4 Array Data: Six-Tower Array, Day Pattern......Page 179
11.3.5 Discussion: Six-Tower Array, Day Pattern......Page 180
11.3.6 NEC-2 Input File......Page 181
11.4.3 Antenna Monitor Readings: Six-Tower Array, Night Pattern......Page 183
11.4.5 Discussion: Six-Tower Array, Night Pattern......Page 184
11.4.6 NEC-2 Input File: Six-Tower Array, Night Pattern......Page 188
11.5.2 Self-Impedance: Tall Towers......Page 189
11.5.4 Array Data: Tall Towers......Page 190
11.5.6 NEC-2 Input File: Tall Towers......Page 192
12.2 Parallel Feeds: Network Combiners......Page 194
12.3 New Structures: The NX Command......Page 196
12.4 Numerical Green's Function......Page 198
12.5.1 The GN Command......Page 200
12.5.2 The GR Command......Page 201
12.6 Finite Ground......Page 204
12.6.2 Sommerfeld/Norton Analysis......Page 205
APPENDIX A: NEC-2 Input File Statements......Page 208
1.0 Comment Commands (CM, CE)......Page 210
2.0 Structure Geometry Commands......Page 212
3.0 Program Control Commands......Page 234
APPENDIX B: Error Messages......Page 274
1.2 Disk Content......Page 282
2.1 Software Installation......Page 283
3.1.1 bnec.exe......Page 285
3.2 NVCOMP.EXE......Page 286
3.3 NecDrv2.EXE......Page 288
3.5 WJGRAPS.EXE......Page 289
4.1 Software Support......Page 290
B......Page 292
D......Page 293
G......Page 294
I......Page 295
N......Page 296
O......Page 297
S......Page 298
T......Page 299
X......Page 300
