Practical_Antenna_Handbook_0071639586

752 I n d e x
history of radio communications, 3–6
homeowners’ association, 703
Hopengarten, Fred, K1VR, 702, 704
horizon, distance to, 34–36
horizontal dipole (See dipole)
horizontal polarization, 18–19, 248–249, 473
horn antenna radiators, 479
hula hoop antenna (See directional
discontinuity ring radiator)
Huygens-ÂFresnel wave theory, 24
I
image antenna, 164–165, 311, 320
imaginary numbers, 724–726
imaginary operator (i; see j)
impedance, 84, 140–141, 473
free-Âspace, 95
impedance bridges, 590–596
impedance matching, 138–147, 533–544
antenna tuners, 533–544
baluns, 139–140, 215
benefits, 533–534
complex conjugate, 142, 725–726
electrical vs. physical length, 139, 143,
146–147
L-Âsection network, 366, 535–537
pi network, 537–538
quarter-Âwave (“Q”) section, 143–145,
213
reactance cancellation, 534–535
reverse ÂL-Ânetwork, 536–537, 539
series section for, 145–147
split-Âcapacitor network, 538–539
stubs, 140–142, 579–582
T-Ânetwork, 539
toroidal transformers, 540–544
transmatch, 538–539
(See also specific antenna types)
incident angle, 22–23, 47, 59–63
incident (or forward) current, 99
incident (or forward) power (P FWD ), 134
incident (or forward) voltage, 99
incident wave, 22–23, 93–96
inductance, 83–84
Grover’s equation, 345
induction field, 9, 14, 87–90
inductively loaded antennas (See Âcoil-Âloaded
antennas)
inductive reactance (X L ), 83–84
inductor, 83–84
installation and construction techniques (See
supports; towers)
insulators, 197, 220, 296, 337, 365, 406–408,
629–638, 642, 674
(See also spreaders)
intensity of radio waves, 15–17
interference:
adjacent-Âchannel, 156, 360
atmospheric (QRN), 331, 389
co-Âchannel, 156
destructive, 28, 32
electromagnetic (EMI), 337, 361, 366
intersystem, 477
man-Âmade (QRM), 266
interferometer antennas, 508–509
International Telecommunications Union
(ITU), 4
Internet resources, 743–744
inverse square law (1/d 2 ), 14, 17, 471–472
inverted-ÂL antenna, 394–395, 415
1.8 MHz, 416–419
on its second harmonic, 418–419
inverted-Âvee dipole, 187–191, 394, 416
dimensions, 188–189
polarization, 189–191
radiation pattern, 189–191
ionization, 9, 22, 26, 45, 48, 52–53, 57,
75, 76
ionogram, 53
ionosonde, 54
ionosphere, 20–22
11- and 22-year cycles, 57
27-day cycle, 56
angle of incidence, 47, 59–63
critical angle (α r ), 47
critical frequency (f C ), 47, 70
dispersion, 67
diurnal variations, 56
frequency of optimum traffic (FOT), 55
layers, 21
lowest useable frequency (LUF),
55–56
seasonal variation, 56
take-Âoff angle (angle of incidence), 47,
59–63
virtual height, 47, 54
ionospheric disturbances, 57–58
ionospheric fading, 57–58, 67–68
(See also fading)