Index

A

Alpha angle, 18–19

ANTENNA ENVIRONMENT, 183

ANTENNA INPUT PARAMETERS, 61, 98

drive point impedances in, 100–102

antenna input parameters, 22, 23

antenna monitor readings, 94–100

base current samples, 97–99

base voltage samples, 99–100

height for sample loops, 96–97

optimum height for sample loops in, 95–96

six-tower array, day pattern, 155–156

six-tower array, night pattern, 160, 161, 162

tall-tower array, 167

three-tower array, 151

antenna-tuning units (ATUs) drive voltages, 140–141

impedance of, 138–139

input impedances, 142

tower base impedances, 141–142

transmission line impedances, 143–144

array adjustment, 1–7

directional, 1–2

local and global minima in, 2–4

mathematical synthesis in, 2

nature of NEC-2 and, 1

physical, 2

role of NEC-2 in, 4

array geometry, 41–50

array input file for, 46–49

coordinate system in, 41–44

example of, 44–46

ATUs. See antenna-tuning units AUTOEXEC.BAT file, 17

azimuth angle, 24–25

displacement, 41

six-tower array, night pattern, 164

B

bandwidth analysis, 133–148

base drive voltages, 63–80

in antenna monitor readings, 99–100

current moments and, 66–67, 73–77

direct and induced current, 63–65

drive point impedance and, 101

example of, 72–79

field ratio calculation and, 67–72

full power drive, 71, 78–79

normalized drive, 69–71, 77–78

shunt reactance and, 71–72

source impedance of, 137–140

in system bandwidth analysis, 136, 137–140

tall-tower array, 167, 168

unity drive, 68–69, 72–77

base insulators, 107

capacity of, 116–118

drive segment radius and, 118–120

modeling by measurement, 116–118

in system bandwidth analysis, 135–136

base loading detuning by, 85–88

skirting with, 92–93

Beta angle, 18–19

bnec.exe, 260, 262–263

reading, 17–25

Burke, G. J., xiii–xiv, xv, 9–10

buss voltage, 144–145

C

CALL_1.NEC, 68–69

CALL.NEC file running, 17

CALL_N.NEC, 71

CALL_N.OUT, 71, 266

CALL.OUT, 81, 266. See also output files

CALL_1.OUT, 68

Carlier, P., xix

carrier frequency, 134

case studies, 149–169

six-tower array, day pattern, 154–159

six-tower array, night pattern, 160–165

tall-tower array, 166–169

three-tower array, 149–154

CE command input file, 14, 188

NX and, 174, 176

circular polarization, 9

clip lead resistance, 107–108

CM command input file, 14, 188

NX and, 174

commands. See also individual commands

comment, 187–188

program control, 13, 16–17, 212–250

structure geometry command, 189–210

comment commands, 13, 14, 187–188

CE, 14, 174, 176, 188

CM, 14, 188174

common point-matching networks, 146

compass headings, 42, 43–44

“Computer Analysis of the Bottom-fed Fan Antenna” (Burke and Poggio), 171

connection data, 19–20

coordinate planes, reflection in, 205–208

coordinate transformation, 195–196

coupling calculation, 212

CP command, 212

Cram, P., xix

current in antenna monitor readings, 97–99

base voltage and, 67–68

direct, 63–65

distribution, listing, 6, 95–96

field ratios and, 82

induced, 63–65

and location output file, 22–23

phase shift, 140–141

sinusoidal distribution of, 66

top loading, 122–126

current moments, 23–24

base drive voltage and, 66–67

base voltage and, 67–68

field ratios and, 82

unity drive, calculating, 73–77

cylindrical structures, 9

generating, 198–200

D

data command, 12–13

delimiting, 12

output file, 21–22

types of, 13

data storage for plotting, 128, 238–239

detuning towers, 84–94

by base loading, 85–88

by skirting, 89–94

directional antenna adjustment, 1–2

drive point impedance, 100–102

bandwidth analysis and, 138–139

base capacity and, 117–118

modeling by measurement, 105–120

six-tower array, day pattern, 156

six-tower array, night pattern, 161–164

tall-tower array, 168

three-tower array, 152–153

tower diameter and, 111–114

drive segment radius, 118–120

drive signal simulation, 148

drive splitting, 171–173

drive voltage, 47–48

dummy wires, 101

E

EK command, 213

in modeling by measurement, 109

elevation angle, 41, 42, 43

elliptical polarization, 9

EN command, 214

end geometry input, 191–192

end of run command, 214

environment data, 21–22

error messages, 251–258

errors, input file, 17

excitation command. See EX command

EX command, 16, 211, 215–218

in network modeling, 56–57

voltage source modeling with, 29–30, 137

execute command, 211, 249–250

extended thin-wire kernel approximation, 213

F

far-field pattern listings, 81

far-field radiation patterns, plotting, 83–84

field ratios in detuning by skirting, 91–92

local and global minima and, 2–3

six-tower array, night pattern, 164

verifying, 82

finite grounds, 9, 181–183

FLMO.NEC, 130–131

folded monopole towers, 32, 129–131

four-wire configurations, 31–32

FR command, 16, 211, 219–220

in bandwidth analysis, 137

frequency in bandwidth analysis, 137

FR command, 16, 211, 219–220

program control command and, 21–22

full power drives, 71

voltage calculation, 78–79

G

GA command, 190

GC command, 202–204

segment and radius taper and, 114–116

in system bandwidth analysis, 136

GD command, 221–222

GE command, 191–192

input file, 15–16

NX and, 176

geometry command, 13

input file, 14–16

geometry print control, 197

GF command, 193

GH command, 194

global minima, 2–4

GM command, 11, 195–196

in detuning by skirting, 90, 93–94

folded monopoles and, 130–131

NX and, 176

in radiator modeling, 38

stacking sections with, 32, 36–37, 38

GN command, 177–178, 223–225

input file, 16

GP command, 197

GR command, 178–181, 198–200

NX and, 176

grounding straps, 34–35

ground parameters, 177–178, 223–225

additional, 221–222

grounds, finite, 9, 181–183

ground screens, 28, 177–181

GS command, 201

NX and, 176

GW command, 202–204

array geometry with, 46, 47

in detuning by skirting, 93–94

drive wire definition with, 33–34

input file, 14–15

in network modeling, 56

in system bandwidth analysis, 136

GX command, 205–208

NX and, 176

H

Hatfield, J. B., 106–107

height adjustment, 35

array geometry for, 44

optimum height for antenna monitor reading sample loops, 95–96

for sample loops in antenna monitor readings, 96–97

helix and spiral specification, 194

helix structures, 9

I

IEEE Transactions on Broadcasting (Trueman), 63, 133

impedance. See also drive point impedances ATU input, 142

base capacity and, 116–118

calculating intermediate data on, 140–141

drive point, 100–102

drive segment radius and, 118–120

load, 51–53, 60–61

matching, 53

modeling by measurement, 105–120

parallel feeds and, 171–173

in parallel in networks, 56

phasing network input, 143, 145

power divider input, 143, 145

segment number vs., 108–109

self-, 149–151, 154–155, 160, 166, 171–172

series, 55–56, 57

shunt, 57

source, 60–61, 137–140

tall-tower array, 167

taper and, 114–116

thin vs. thick wire, 109–110

tower base, 141–142

tower diameter and, 111–114

transmission line input, 143–144

in transmission line modeling, 58

inductance in detuning by base loading, 85–86

in LD command, 52

in modeling by measurement, 107

test lead, 107–108

input files array, 46–49

base loading, 88

command for, 185–250

comment command, 187–188

creating, 11–17

data command with, 12–13

detuning by skirting, 93–94

illustration of, 13–17

naming, 11–12

normalized drive, 5

six-tower array, day pattern, 158–159

six-tower array, night pattern, 165

structure geometry command, 189–210

tall-tower array, 168, 169

three-tower array, 153–154

unity drive, 5

interaction approximation range, 226

K

KH command, 226

L

lattice configurations, 32–38

coding, 33–37

current distribution in, 121

parallel feeds in, 171–173

simplifi ed, 37–38

skirted, 121, 126–128

in system bandwidth analysis, 134–135

top-loaded, 121–126

Lawrence Livermore National Laboratories, xv, 9–10

LD command, 227–229

array geometry and, 48

in detuning by skirting, 93

floating-point numbers in, 52

in impedance load modeling, 51–53

NX and, 176

load modeling, 227–229. See also LD command

impedance, 51–53

program control command and, 21–22

shunt impedance, 53

voltage source and, 57, 58

local minima, 2–4

loss modeling, 48

M

mathematical synthesis, in array adjustment, 2

measurement, modeling by, 105–120

adjustments in, 107–120

base capacity in, 116–118

drive segment radius in, 118–120

objectives of, 105–107

radius taper in, 114–116

segment length in, 114–116

segment number in, 107, 108–111

tower diameter in, 111–114

modeling rules, 178–179

monopoles folded, 32, 129–131

ground screens and, 179–180

Morecroft, J. H., 31

N

Naval Ocean Systems Center Technical Document 116

(TD 116), 185

near fields, 230–232

NecDrv2.EXE, 77–78, 260, 265–266

NEC2ds.zip, 262–263

NEC2dxs.xip files, 10

NECMOM.EXE, 181, 260, 266

NEC-2 (Numerical Electromagnetics Code version 2), xv, 5–6

benefits of, 6–7

case studies, 149–169

development of, 9–10

nature of, 1

operation of, 11

public domain software with, 5

role of in array adjustment, 4

scope of, 9

software requirements, 7

software with, 259–266

user-friendliness of, xv

NEC-4 (Numerical Electromagnetics Code version 4), 10

NE command, 230–232

current computation with, 211

network modeling. See also NT command

common applications and, 55–57

common configurations, 53–55

common point-matching, 146

descriptions in, 59–60

drive point impedances in, 100–102

guidelines for, 57

input parameters in, 61

nonradiating, 53–57

NT command, 233–235

output files in, 59–61

parallel feeds in, 56, 171–173

phasing input impedances in, 144, 145

shunt reactance and, 71–72

source and load impedance in, 60–61

voltage transmission between networks in, 140–141

network phase, 53, 140–141

networks drive splitting in, 171–173

next structure command, 173–177, 236

NGF files. See also Numerical Green's Function

reading, 193

writing, 248

NH command, 230–232

current computation with, 211

normalized drives, 69–71

voltage calculation, 77–78

NT command, 233–235

in bandwidth analysis, 137

in load modeling, 52

in network modeling, 57

in nonradiating network modeling, 53

NX and, 176

Numerical Electromagnetic Code (NEC) — Method of Moments, Part III: User's Guide, 185

Numerical Green's Function, 9, 175–177

NVCOMP.EXE, 38–39, 260, 263–265

detuning by base loading and, 90–91

folded monopoles in, 131

skirted towers in, 128–129

top loading in, 124–125

NV.EXE, 38

NX command, 173–174, 236

CE and, 176

Numerical Green's Function and, 175–177

O

output files, 5, 81–103

antenna input parameters in, 22, 23

antenna monitor readings in, 94–100

condensed, 81

current moments in, 23–24

currents and locations in, 22–23

data command with, 21–22

detuning towers with, 84–94

drive point impedances, 100–102

far-field radiation patterns and, 83–84

field ratio verification in, 82

header in, 18

network, 59–61

power budget in, 24, 25

radiation patterns in, 24–25

reading, 17–25

segmentation data in, 18–21, 81

skirted towers, 128–129

structure specifications for, 18, 19

P

parallel feeds, 56, 171–173

parasitic radiation, comparisons for, 174

pass-through networks, 55

peak values, 22, 23

phase local and global minima and, 2–3

network, 53, 140–141

phasing network input impedance, 143, 145

shift, 140–141

phasing networks, 53

phi angle, 24–25

Pi-networks, 57

PL command, 238–239

vertical radiation patterns and, 128

plotting, 128, 238–239

Poggio, A. M., xv, 9–10

power budget, 24, 25, 71

full power drive, 78–79

power divider input impedances, 143, 145

PQ command, 237

Principles of Radio Communication (Morecroft), 31

print control, 237, 240–241

program control command, 13, 16–17, 212–250

PT command, 240–241

R

radiation patterns, 24–25, 242–245. See also RP command

bandwidth, 146–147

detuning unused towers and, 84–94

folded monopole, 129–131

parasitic, 157–158, 162–163, 174

six-tower array, day pattern, 157–158

six-tower array, night pattern, 162–164

skirted towers, 121, 126–128

WJGRAPS.EXE for, 266–267

radiator modeling, 27–39

in lattice configurations, 35

tower configurations, 30–39

voltage source in, 29–30

radius taper, 114–116

reactance physical shunting, 98–99

shunt, 71–72, 107

Reflection Coefficient Approximation (RCA), 182

reflection in coordinate planes, 205–207

ring girth, 37

coding, 34

defining, 33

top loading and, 124

RP. See radiation patterns

RP command, 16–17, 242–245

array geometry and, 48

current computation with, 211

in plotting far-field radiation patterns, 83–84

S

scaling structure dimensions, 201–204

segmentation data, 81

segment lengths intersection angle of, 28

load and, 52

in output files, 22–23

print control for charge on, 237

radiator modeling, 27–28, 29

radius taper and, 114–116

in system bandwidth analysis, 136

thick wire vs. thin wire, 108–110

underground, 178–179

segment numbers, in modeling by measurement, 107, 108–111

self-impedance parallel feeds and, 171–172

six-tower array, day pattern, 154–155

six-tower array, night pattern, 160

tall-tower array, 166

three-tower array, 149–151

Sellmeyer, J., 149, 154, 160

shunt admittances, 59

shunt reactance, 71–72

in modeling by measurement, 107

single-wire configurations, 31

six-tower arrays day pattern, 154–159

night pattern, 160–165

skirted towers, 32, 121, 126–131

base loading and, 92–93

detuning with, 89–94

folded monopoles and, 129–131

SM command, 210

software, 259–267

installation of, 260–262

Sommerfeld/Norton finite-ground method, 9, 182–183

SP command, 9, 208–209

spider girth, 35, 37

defining, 33

top loading and, 124

spiral specification, 194

SQR.OUT base current samples and, 97–99

drive point impedances in, 100–102

in plotting far-field radiation patterns, 83–84

SQR_1.OUT, 73

STRUCTURE EXCITATION DATA AT NETWORK CONNECTION POINTS, 60–61

structure geometry command, 189–210

“A Study of AM Tower Base Impedance” (Hatfield), 106–107

Stumpff, G., 38

surface patches, 9, 208–209

multiple, 210

system bandwidth analysis, 133–148

base drive voltages in, 136, 137–140

common point-matching networks, 146

drive signal simulation in, 148

intermediate data in, 140–146

low-impedance towers and, 148

parameter smoothing in, 148

radiation bandwidth, 146–147

system definition for, 133–136

total system data in, 146–147

transmission lines in, 148

T

tall-tower arrays, 166–169

templates, array input file, 48–49

TD 116, 185

TEMP.NEC, 49

test lead inductance, 107–108

text editing, 17

theta angle, 24–25, 42

three-tower arrays, 149–154

TL command, 57–59, 246–247

in bandwidth analysis, 134, 137

TL.NEC, 124

T-networks, 57, 101

top loading, 32

determining degree of, 123–126

top hat size estimation in, 122–123

tower base impedances, 141–142

tower configurations, 30–38

drive segment radius, 118–120

flexibility in modeling, 109

folded monopole, 129–131

four-wire, 31–32

lattice, 30, 32–38

new structure creation, 173–177

NX command for, 173–174

single-wire, 31

skirted, 121, 126–131

in system bandwidth analysis, 134–136

thick-wire, 30

three-tower, 149–154

top-loaded, 121–126

tower diameter in, 111–114

triangular, 30

two-wire, 32

viewing, 38–39

tower feeds, 53

transmission line modeling, 57–59, 246–247

frequency vs. carrier frequency and, 148

input impedances, 143–145

in system bandwidth analysis, 134, 137

Trueman, C. W., 63

twotwr.nec, 181

two-wire configurations, 32

U

unity drives, 68–69

creating files for, 72–73

current moment calculation, 73–77

unity excitation, 68

V

voltage modeling, 16–17

antenna monitor readings and, 99–100

array geometry and, 47–48

base drive, 63–80

buss, 144–145

driving point, calculating, 72–79

full power, 78–79

load, network, and source of, 57, 58

normalized drive, 77–78

source, 29–30

voltage sources, 52

impedance of drive voltage and, 137–140

W

WG command, 248

wire arc specification, 190

wire radius, 28, 29

wire specification, 202–204

wire structure modeling, 10

WJGRAPS.EXE, 260, 266–267

WordPad, 81

X

XQ command, 211, 249–250