Practical_Antenna_Handbook_0071639586

I n d e x 767
Yagi antennas (Cont.):
aluminum tubing, 293
back lobes, 279
bandwidth, 292
beam vs. beamwidth, 278
beamwidth, 279
BIP (beams in phase), 309–312
boom, 279, 284, 292, 293–295
boom-Âto-Âmast and Âboom-Âto-Â
element brackets, 296
BOP (beams out of phase), 309–312
construction and materials, 286–299
dimensions, 282–286
director, 280
driven element, 280, 285
element(s):
caps, 291
diameter and nesting, 282–283,
285, 290, 293–297
Leeson corrections, 293
linear loading, 301–302
loading coils, 301–302
traps, 299–301
element spacing, 281, 284
feedpoint impedance and matching, 285,
291, 296, 297, 302–306
balun feed, 302
gamma match, 302–304
hairpin match, 305–306
T-Âmatch, 304–305
four or more elements, 286
front-Âto-Âback (F/B) ratio, 284, 285
front-Âto-Âside (F/S) ratio, 285
gain, 278, 284
long-Âboom, 63
modeling, 292, 293–295
Yagi antennas (Cont.):
multiband, 299–301, 678
optimum height, 63
pattern, 278
reflector, 280
multiple, 286
scaling for other frequencies, 283–284
shortened elements, 285, 299–302
side lobes, 279
stacking, 308–313
distance, 308–313
gain, 310–312
multiple bands, 312–313
for same band, 308–312
test and measurement, 291
three-Âelement, 279–286
as Âtop-Âloading for fed towers, 286,
406–412
triband, 299–301, 678
two-Âelement, 282, 297–299
wind and ice loads, 290, 296
wire construction, 297–299
Yagi-ÂUda antenna, 162, 277–314
Z
Zepp, 222–224
(See also extended double Zepp)
zip cord (lamp cord), 394
ZL-Âspecial beam antenna, 264
feedpoint impedance and matching,
264
zoning and regulatory, 699–704
Zoning Board of Appeals (ZBA), 702–703
zoning office, 701–702, 704
Zurich Smoothed Sunspot Number, 49