Practical_Antenna_Handbook_0071639586

Recommendations

Info

C h a p t e r 3 : A n t e n n a B a s i c s 97 • At the ends of a longer dipole, the current in the dipole must go to zero even though the current at the feedpoint is still I 0 . The contribution to the received signal at a distant point from each short segment of the antenna is then summed at the distant location, taking into account the different propagation times to the receiving antenna from different segments of the source dipole. In this model of a longer dipole, a current introduced at the feedpoint travels along the wire to or from each end. However, at the ends, where no current can flow, a reflection occurs and new currents start back toward the center. We will look at this process in more detail in the next section, but the net effect is that a standing wave of time-varying current (and a similar one for voltage) is created on the wire. This standing wave represents a vector combination of the outbound and returning currents at each point along the dipole. It is the amplitude and phase of this standing wave rather than the individual outbound and returning currents that we use for calculating the contribution of each tiny element of the model to the total radiation detected at a distant point from this dipole. The most common models use either a straight-line decrease of current from the feedpoint to each end or a sinusoidal distribution (again based on reaching zero current at the ends) assuming a source frequency f 0 . The resulting E-field and H-field expressions for longer dipoles are identical to Eqs. (3.19) and (3.20) except for one difference: The sinq term of those equations is now replaced with ⎛ πh ⎞ πh cos cosθ cos ⎝ ⎜ λ ⎠ ⎟ − λ sin θ (3.27) For the special case of the half-wave dipole, Eq. (3.27) reduces to ⎛ π ⎞ π cos cosθ cos ⎝ ⎜ 2 ⎠ ⎟ − 2 sin θ (3.28) Of course, cos (π/2) = cos 90 o = 0, so the second term goes away. Broadside to the axis of the dipole, q = 90o , so the remaining term in the numerator becomes cos 0 o and the entire term has a value of 1.0. Figure 3.7 is a graphical representation of the geometrical variation given by Eq. 3.28—the well-known doughnut pattern of a half-wavelength dipole. When all the approximations are accounted for, the l/2 dipole has 0.4 dB more gain in its main lobe than the hertzian dipole does, and the lobe is slightly narrower than that of the hertzian dipole—but these comparisons are meaningless to everyone except physics professors and their students since it is virtually impossible in the real world to deliver any significant transmitter power to an infinitesimally short dipole! The big news with the l/2 dipole is actually its feedpoint impedance, which in free space is 73 W resistive, with little or no reactive component. This high value of R RAD makes the antenna easy to match with commonly available transmission lines, but, more important, makes it much easier to deliver most of the transmitter output power
98 P a r t I I : F u n d a m e n t a l s C <strong>Antenna</strong> axis B End view of vertical plane (rotated 90˚ from solid figure) 315 270 A Top view of horizontal plane (rotated 90˚ from solid figure) 0 90 45 Figure 3.7 Free-space radiation pattern of l/2 dipole. to the antenna rather than seeing it dissipate in the resistance of conductors and connectors. Standing Waves Assume that it is possible to have a wire conductor with one end extending infinitely, with a transmitter or other source of RF energy of single frequency f 0 connected to this wire. When the transmitter is turned on, an alternating current consisting of sine waves propagates along the wire. These waves are called traveling waves, and, although the
Page 2 and 3:
Practical Antenna Handbook
Page 4 and 5:
Practical Antenna Handbook Joseph J
Page 6 and 7:
Contents Preface . . . . . . . . .
Page 8 and 9:
C o n t e n t s vii 12 The Yagi-Uda
Page 10 and 11:
C o n t e n t s ix Switched-Pattern
Page 12 and 13:
Preface My paternal grandfather was
Page 14 and 15:
P r e f a c e xiii this book repres
Page 16 and 17:
Acknowledgments As with other field
Page 18 and 19:
Background and History Part I Chapt
Page 20 and 21:
CHAPTER 1 Introduction to Radio Com
Page 22 and 23:
C h a p t e r 1 : I n t r o d u c t
Page 24 and 25:
Fundamentals Part II Chapter 2 Radi
Page 26 and 27:
CHAPTER 2 Radio-Wave Propagation To
Page 28 and 29:
C h a p t e r 2 : r a d i o - W a v
Page 30 and 31:
Page 32 and 33:
Page 34 and 35:
Page 36 and 37:
Page 38 and 39:
Page 40 and 41:
Page 42 and 43:
R N-1 C h a p t e r 2 : r a d i o -
Page 44 and 45:
Page 46 and 47:
Page 48 and 49:
Page 50 and 51:
Page 52 and 53:
Page 54 and 55:
Page 56 and 57:
Page 58 and 59:
Page 60 and 61:
Page 62 and 63:
Page 64 and 65: C h a p t e r 2 : r a d i o - W a v
Page 68 and 69: Figure 2.29C Monthly averaged sunsp
Page 98 and 99: CHAPTER 3 Antenna Basics An antenna
Page 100 and 101: C h a p t e r 3 : A n t e n n a B a
Page 126 and 127: CHAPTER 4 Transmission Lines and Im
Page 128 and 129: C h a p t e r 4 : T r a n s m i s s
Page 164 and 165:
C h a p t e r 4 : T r a n s m i s s
Page 166 and 167:
Chapter 5 Antenna Arrays and Array
Page 168 and 169:
C h a p t e r 5 : a n t e n n a A r
Page 170 and 171:
Page 172 and 173:
Page 174 and 175:
Page 176 and 177:
Page 178 and 179:
Page 180 and 181:
Page 182 and 183:
Page 184 and 185:
Page 186 and 187:
A. B. C. D. E. F. G. H. Figure 5.9
Page 188 and 189:
B. C. D. E. F. G. H. Figure 5.10 Gr
Page 190 and 191:
High-Frequency Building-Block Anten
Page 192 and 193:
CHAPTER 6 Dipoles and Doublets A co
Page 194 and 195:
C h a p t e r 6 : D i p o l e s a n
Page 196 and 197:
Page 198 and 199:
Page 200 and 201:
Page 202 and 203:
Page 204 and 205:
Page 206 and 207:
Page 208 and 209:
Page 210 and 211:
Page 212 and 213:
Page 214 and 215:
Page 216 and 217:
Page 218 and 219:
Page 221 and 222:
Page 223 and 224:
Page 225 and 226:
CHAPTER 7 Large Wire Loop Antennas
Page 227 and 228:
C h a p t e r 7 : L a r g e W i r e
Page 229 and 230:
Page 231 and 232:
Page 233 and 234:
Page 235 and 236:
CHAPTER 8 Multiband and Tunable Wir
Page 237 and 238:
C h a p t e r 8 : M u l t i b a n d
Page 239 and 240:
Page 241 and 242:
Page 243 and 244:
Page 245 and 246:
Page 247 and 248:
CHAPTER 9 Vertically Polarized Ante
Page 249 and 250:
C h a p t e r 9 : V e r t i c a l l
Page 251 and 252:
Page 253 and 254:
Quarter-wave vertical radiator Insu
Page 255 and 256:
Page 257 and 258:
Page 259 and 260:
Page 261 and 262:
Page 263 and 264:
Page 265 and 266:
Page 267 and 268:
Page 269 and 270:
Directional High-Frequency Antenna
Page 271 and 272:
CHAPTER 10 Wire Arrays When a singl
Page 273 and 274:
C h a p t e r 1 0 : W i r e A r r a
Page 275 and 276:
Page 277 and 278:
Wire 2 C h a p t e r 1 0 : W i r e
Page 279 and 280:
Page 281 and 282:
Page 283 and 284:
CHAPTER 11 Vertical Arrays Despite
Page 285 and 286:
C h a p t e r 1 1 : V e r t i c a l
Page 287 and 288:
Page 289 and 290:
Page 291 and 292:
Page 293 and 294:
Page 295 and 296:
CHAPTER 12 The Yagi-Uda Beam Antenn
Page 297 and 298:
C h a p t e r 1 2 : T h e Y a g i -
Page 299 and 300:
Page 301 and 302:
Page 303 and 304:
Page 305 and 306:
Page 307 and 308:
Page 309 and 310:
Page 311 and 312:
Page 313 and 314:
Page 315 and 316:
Page 317 and 318:
Page 319 and 320:
Page 321 and 322:
Page 323 and 324:
Page 325 and 326:
Page 327 and 328:
Page 329 and 330:
Page 331 and 332:
Page 333 and 334:
CHAPTER 13 Cubical Quads and Delta
Page 335 and 336:
C h a p t e r 1 3 : C u b i c a l Q
Page 337 and 338:
Page 339 and 340:
Page 341 and 342:
Figure 13.5 Multiband quad “spide
Page 343 and 344:
Page 345 and 346:
Page 347 and 348:
High-Frequency Antennas for Special
Page 349 and 350:
CHAPTER 14 Receiving Antennas for H
Page 351 and 352:
C h a p t e r 1 4 : r e c e i v i n
Page 353 and 354:
Page 355 and 356:
Page 357 and 358:
Page 359 and 360:
Page 361 and 362:
Page 363 and 364:
Page 365 and 366:
Page 367 and 368:
Page 369:
351 Figure 14.12 Remote tuning sche
Page 372 and 373:
Page 374 and 375:
Page 377 and 378:
Page 379 and 380:
Page 381 and 382:
Page 383 and 384:
CHAPTER 15 Hidden and Limited-Space
Page 385 and 386:
C h a p t e r 1 5 : H i d d e n a n
Page 387 and 388:
Page 389 and 390:
Page 391 and 392:
Page 393 and 394:
Page 395 and 396:
CHAPTER 16 Mobile and Marine Antenn
Page 397 and 398:
C h a p t e r 1 6 : M o b i l e a n
Page 399 and 400:
Page 401 and 402:
Page 403 and 404:
Page 405 and 406:
Page 407 and 408:
Page 409 and 410:
CHAPTER 17 Emergency and Portable A
Page 411 and 412:
C h a p t e r 1 7 : E m e r g e n c
Page 413 and 414:
Page 415 and 416:
Page 417 and 418:
Page 419 and 420:
Antennas for Other Frequencies Part
Page 421 and 422:
CHAPTER 18 Antennas for 160 Meters
Page 423 and 424:
C h a p t e r 1 8 : a n t e n n a s
Page 425 and 426:
Page 427 and 428:
Page 429 and 430:
Page 431 and 432:
Page 433 and 434:
Page 435 and 436:
Page 437 and 438:
Page 439 and 440:
Page 441 and 442:
Page 443 and 444:
Page 445 and 446:
CHAPTER 19 VHF and UHF Antennas The
Page 447 and 448:
C h a p t e r 1 9 : V H F a n d U H
Page 449 and 450:
Page 451 and 452:
Page 453 and 454:
Page 455 and 456:
Page 457 and 458:
Page 459 and 460:
Page 461 and 462:
Page 463 and 464:
Page 465 and 466:
Page 467 and 468:
CHAPTER 20 Microwave Waveguides and
Page 469 and 470:
C h a p t e r 2 0 : M i c r o w a v
Page 471 and 472:
Page 473 and 474:
Page 475 and 476:
Page 477 and 478:
Page 479 and 480:
Page 481 and 482:
λ o = c / f 8 3× 10 m / s = 9 C h
Page 483 and 484:
Page 485 and 486:
Page 487 and 488:
Page 489 and 490:
Page 491 and 492:
Page 493 and 494:
Page 495 and 496:
Page 497 and 498:
Page 499 and 500:
Page 501 and 502:
Page 503 and 504:
Page 505 and 506:
Page 507 and 508:
Page 509 and 510:
Page 511 and 512:
CHAPTER 21 Antenna Noise Temperatur
Page 513 and 514:
C h a p t e r 2 1 : A n t e n n a N
Page 515 and 516:
C h a p t e r 2 1 : A n t e n n a N
Page 517 and 518:
CHAPTER 22 Radio Astronomy Antennas
Page 519 and 520:
C h a p t e r 2 2 : R a d i o A s t
Page 521 and 522:
Page 523 and 524:
Page 525 and 526:
Page 527 and 528:
Page 529 and 530:
Figure 22.9 Interferometer pattern.
Page 531 and 532:
CHAPTER 23 Radio Direction-Finding
Page 533 and 534:
C h a p t e r 2 3 : R a d i o D i r
Page 535 and 536:
Page 537 and 538:
Page 539 and 540:
Page 541 and 542:
Figure 23.9 Adcock array RDF antenn
Page 543 and 544:
Figure 23.11 Watson-Watt Adcock arr
Page 545 and 546:
Page 547 and 548:
Page 549 and 550:
Page 551 and 552:
Tuning, Troubleshooting, and Design
Page 553 and 554:
CHAPTER 24 Antenna Tuners (ATUs) Th
Page 555 and 556:
C h a p t e r 2 4 : a n t e n n a T
Page 557 and 558:
Page 559 and 560:
Page 561 and 562:
Page 563 and 564:
Page 565 and 566:
CHAPTER 25 Antenna Modeling Softwar
Page 567 and 568:
C h a p t e r 2 5 : A n t e n n a M
Page 569 and 570:
Page 571:
Figure 25.3B Bent dipole wire and s
Page 574 and 575:
Page 576 and 577:
Page 578 and 579:
Page 580 and 581:
CHAPTER 26 The Smith Chart The math
Page 582 and 583:
Figure 26.2 Normalized impedance li
Page 584 and 585:
A Figure 26.3 Constant resistance c
Page 586 and 587:
A Figure 26.4A Constant inductive r
Page 588 and 589:
C h a p t e r 2 6 : T h e S m i t h
Page 590 and 591:
Page 592 and 593:
D C B A Figure 26.5 Radially scaled
Page 594 and 595:
Page 596 and 597:
Page 598 and 599:
Page 600 and 601:
Page 602 and 603:
0.165 Y ' 1.0 j1.1 G' 1.0 Y ' 0.2
Page 604 and 605:
Page 606 and 607:
Page 608 and 609:
CHAPTER 27 Testing and Troubleshoot
Page 610 and 611:
C h a p t e r 2 7 : T e s t i n g a
Page 612 and 613:
Page 614 and 615:
Page 616 and 617:
Page 618 and 619:
Page 620 and 621:
Page 622 and 623:
Page 624 and 625:
Page 626 and 627:
Page 628 and 629:
Page 630 and 631:
Page 632 and 633:
Page 634 and 635:
Page 636 and 637:
Page 638 and 639:
Page 640 and 641:
Page 642 and 643:
Page 644 and 645:
Mechanical Construction and Install
Page 646 and 647:
CHAPTER 28 Supports for Wires and V
Page 648 and 649:
C h a p t e r 2 8 : S u p p o r t s
Page 650 and 651:
Page 652 and 653:
Page 654 and 655:
Page 656 and 657:
Page 658 and 659:
Page 660 and 661:
Page 662 and 663:
Page 664 and 665:
Page 666 and 667:
Page 668 and 669:
Page 670 and 671:
Page 672 and 673:
Page 674 and 675:
CHAPTER 29 Towers At some point, th
Page 676 and 677:
C h a p t e r 2 9 : T o w e r s 655
Page 678 and 679:
C h a p t e r 2 9 : T o w e r s 657
Page 680 and 681:
C h a p t e r 2 9 : T o w e r s 659
Page 682 and 683:
C h a p t e r 2 9 : T o w e r s 661
Page 684 and 685:
C h a p t e r 2 9 : T o w e r s 663
Page 686 and 687:
C h a p t e r 2 9 : T o w e r s 665
Page 688 and 689:
C h a p t e r 2 9 : T o w e r s 667
Page 690 and 691:
C h a p t e r 2 9 : T o w e r s 669
Page 692 and 693:
C h a p t e r 2 9 : T o w e r s 671
Page 694 and 695:
C h a p t e r 2 9 : T o w e r s 673
Page 696 and 697:
C h a p t e r 2 9 : T o w e r s 675
Page 698 and 699:
C h a p t e r 2 9 : T o w e r s 677
Page 700 and 701:
C h a p t e r 2 9 : T o w e r s 679
Page 702 and 703:
C h a p t e r 2 9 : T o w e r s 681
Page 704 and 705:
CHAPTER 30 Grounding for Safety and
Page 706 and 707:
C h a p t e r 3 0 : G r o u n d i n
Page 708 and 709:
Page 710 and 711:
Page 712 and 713:
Page 714 and 715:
Page 716 and 717:
Page 718 and 719:
Page 720 and 721:
CHAPTER 31 Zoning, Restrictive Cove
Page 722 and 723:
C h a p t e r 3 1 : Z o n i n g , R
Page 724 and 725:
C h a p t e r 3 1 : Z o n i n g , R
Page 726 and 727:
Appendices
Page 728 and 729:
APPENDIX A Useful Math The material
Page 730 and 731:
A p p e n d i x A : U s e f u l M a
Page 732 and 733:
Page 734 and 735:
Page 736 and 737:
Page 738 and 739:
Page 740 and 741:
Page 742 and 743:
Page 744 and 745:
Page 746 and 747:
Page 748 and 749:
Appendix B Suppliers and Other Reso
Page 750 and 751:
A p p e n d i x B : S u p p l i e r
Page 752 and 753:
Page 754 and 755:
Page 756 and 757:
Page 758 and 759:
Page 760 and 761:
B.1.6 Rotators and Controllers Alfa
Page 762 and 763:
Page 764 and 765:
Page 766 and 767:
Index Note: Boldface numbers denote
Page 768 and 769:
I n d e x 747 Binns, Jack, first ma
Page 770 and 771:
I n d e x 749 dipole (Cont.): slopi
Page 772 and 773:
I n d e x 751 grounding and ground
Page 774 and 775:
I n d e x 753 ionospheric propagati
Page 776 and 777:
I n d e x 755 maximum effective len
Page 778 and 779:
I n d e x 757 noise (Cont.): sky no
Page 780 and 781:
I n d e x 759 reactance: cancellati
Page 782 and 783:
I n d e x 761 standing waves: on an
Page 784 and 785:
I n d e x 763 transmission lines, 1
Page 786 and 787:
I n d e x 765 vertically polarized
Page 788:
I n d e x 767 Yagi antennas (Cont.)
show all

Practical_Antenna_Handbook_0071639586

Create successful ePaper yourself

Delete template?

Save as template?