1. Technician License Course Chapter 4 Propagation, Antennas and Feed Lines Lesson Plan Module 10: Practical Antennas

2. The Dipole Most basic antenna. –Two conductive, equal length parts. –Feed line connected in the middle. Total length is ½ wavelength (½ ). Length (in feet) = 468 / Frequency (in MHz).

3. The Dipole

4. The Ground-Plane Simply a dipole that is oriented perpendicular to the Earth’s surface (vertical). One half of the dipole is replaced by the ground- plane. –Earth –Car roof or trunk lid or other metal surface. –Radial wires. Length (in feet) = 234 / Frequency (in MHz).

5. The Ground-Plane

6. Loop Antennas – Variations Quad Delta Horizontal

7. Directional (Beam) Antennas Beam antennas focus or direct RF energy in a desired direction. –Gain –An apparent increase in power in the desired direction (both transmit and receive). Yagi (rod-like elements – TV antennas). Quad (square shape, wire loop elements).

8. Directional (Beam) Antennas

9. All beam antennas have parts called elements. –Driven element is connected to the radio by the feed line. –Reflector element is on the back side. –Director element is on the front side toward the desired direction.

10. Feed Line Devices Balun Duplexer Antenna switch SWR meter Antenna analyzer Antenna tuner

11. Coax Feed Lines RG-58 RG-8 RG-213 RG-174 Hardline

12. Coax Most common feed line. Easy to use. Matches impedance of modern radio equipment (50 ohms). Some loss of signal depending on coax quality (cost).

13. Coax Connectors SO-239/PL-259 BNC N SMA

14. Nothing is Perfect Although the goal is to get 100% of your radio energy radiated into space, that is virtually impossible. What is an acceptable level of reflected power or SWR? –1:1 SWR is perfect. –2:1 SWR should be the max you should accept (as a general rule). Modern radios will start lowering transmitter output power automatically when SWR is above 2:1. –3:1 is when you need to do something to reduce SWR.

15. Test and Matching Equipment Proper impedance matching is important enough to deserve some simple test equipment as you develop your station repertoire. Basic test equipment: SWR meter. Matching equipment: Antenna tuner.

16. Standing Wave Ratio (SWR) If the antenna and feed line impedances are not perfectly matched, some RF energy is not radiated into space and is returned (reflected) back to the source. –Something has to happen to this reflected energy – generally converted into heat or unwanted radio energy (bad).

17. Antenna Tuner One way to make antenna matching adjustments is to use an antenna tuner. Antenna tuners are impedance transformers (they actually do not tune the antenna). –When used appropriately they are effective. –When used inappropriately all they do is make a bad antenna look good to the transmitter…the antenna is still bad.

18. How to use an Antenna Tuner Monitor the SWR meter. Make adjustments on the tuner until the minimum SWR is achieved. –The impedance of the antenna is transformed to more closely match the impedance of the transmitter.

19. SWR Meter The SWR meter is inserted in the feed line and indicates the mismatch that exists at that point. You make adjustments to the antenna to minimize the reflected energy (minimum SWR).

20. Antenna Supports Trees. Towers or masts. Covenants and antenna restrictions must be considered.

21. What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands? (T3A03) A. Right-hand circular B. Left-hand circular C. Horizontal D. Vertical

22. What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands? (T3A03) A. Right-hand circular B. Left-hand circular C. Horizontal D. Vertical

23. When using a directional antenna, how might your station be able to access a distant repeater if buildings or obstructions are blocking the direct line of sight path? (T3A05) A. Change from vertical to horizontal polarization B. Try to find a path that reflects signals to the repeater C. Try the long path D. Increase the antenna SWR

24. When using a directional antenna, how might your station be able to access a distant repeater if buildings or obstructions are blocking the direct line of sight path? (T3A05) A. Change from vertical to horizontal polarization B. Try to find a path that reflects signals to the repeater C. Try the long path D. Increase the antenna SWR

25. What is the primary purpose of a dummy load? (T7C01) A. To prevent the radiation of signals when making tests B. To prevent over-modulation of your transmitter C. To improve the radiation from your antenna D. To improve the signal to noise ratio of your receiver

26. What is the primary purpose of a dummy load? (T7C01) A. To prevent the radiation of signals when making tests B. To prevent over-modulation of your transmitter C. To improve the radiation from your antenna D. To improve the signal to noise ratio of your receiver

27. Which of the following instruments can be used to determine if an antenna is resonant at the desired operating frequency? (T7C02) A. A VTVM B. An antenna analyzer C. A “Q” meter D. A frequency counter

28. Which of the following instruments can be used to determine if an antenna is resonant at the desired operating frequency? (T7C02) A. A VTVM B. An antenna analyzer C. A “Q” meter D. A frequency counter

29. What instrument other than an SWR meter could you use to determine if a feedline and antenna are properly matched? (T7C08) A. Voltmeter B. Ohmmeter C. Iambic pentameter D. Directional wattmeter

30. What instrument other than an SWR meter could you use to determine if a feedline and antenna are properly matched? (T7C08) A. Voltmeter B. Ohmmeter C. Iambic pentameter D. Directional wattmeter

31. Which of the following is the most common cause for failure of coaxial cables? (T7C09) A. Moisture contamination B. Gamma rays C. The velocity factor exceeds 1.0 D. Overloading

32. Which of the following is the most common cause for failure of coaxial cables? (T7C09) A. Moisture contamination B. Gamma rays C. The velocity factor exceeds 1.0 D. Overloading

33. Why should the outer jacket of coaxial cable be resistant to ultraviolet light? (T7C10) A. Ultraviolet resistant jackets prevent harmonic radiation B. Ultraviolet light can increase losses in the cable’s jacket C. Ultraviolet and RF signals can mix together, causing interference D. Ultraviolet light can damage the jacket and allow water to enter the cable

34. Why should the outer jacket of coaxial cable be resistant to ultraviolet light? (T7C10) A. Ultraviolet resistant jackets prevent harmonic radiation B. Ultraviolet light can increase losses in the cable’s jacket C. Ultraviolet and RF signals can mix together, causing interferance D. Ultraviolet light can damage the jacket and allow water to enter the cable

35. What is a disadvantage of “air core” coaxial cable when compared to foam or solid dielectric types? (T7C11) A. It has more loss per foot B. It cannot be used for VHF or UHF antennas C. It requires special techniques to prevent water absorption D. It cannot be used at below freezing temperatures

36. What is a disadvantage of “air core” coaxial cable when compared to foam or solid dielectric types? (T7C11) A. It has more loss per foot B. It cannot be used for VHF or UHF antennas C. It requires special techniques to prevent water absorption D. It cannot be used at below freezing temperatures

37. Which of the following types of solder is best for radio and electronic use? (T7D08) A. Acid-core solder B. Silver solder C. Rosin-core solder D. Aluminum solder

38. Which of the following types of solder is best for radio and electronic use? (T7D08) A. Acid-core solder B. Silver solder C. Rosin-core solder D. Aluminum solder

39. What is the characteristic appearance of a “cold” solder joint? (T7D09) A. Dark black spots B. A bright or shiny surface C. A grainy or dull surface D. A greenish tint

40. What is the characteristic appearance of a “cold” solder joint? (T7D09) A. Dark black spots B. A bright or shiny surface C. A grainy or dull surface D. A greenish tint

41. What is a beam antenna? (T9A01) A. An antenna built from aluminum I- beams B. An omnidirectional antenna invented by Clarence Beam C. An antenna that concentrates signals in one direction D. An antenna that reverses the phase of received signals

42. What is a beam antenna? (T9A01) A. An antenna built from aluminum I- beams B. An omnidirectional antenna invented by Clarence Beam C. An antenna that concentrates signals in one direction D. An antenna that reverses the phase of received signals

43. Which of the following describes a simple dipole mounted so the conductor is parallel to the earth’s surface? (T9A03) A. A ground wave antenna B. A horizontally polarized antenna C. A rhombic antenna D. A vertically polarized antenna

44. Which of the following describes a simple dipole mounted so the conductor is parallel to the earth’s surface? (T9A03) A. A ground wave antenna B. A horizontally polarized antenna C. A rhombic antenna D. A vertically polarized antenna

45. What is a disadvantage of the “rubber duck” antenna supplied with most handheld radio transceivers? (T9A04) A. It does not transmit or receive as effectively as a full-sized antenna B. It transmits a circularly polarized signal C. If the rubber end cap is lost it will unravel very quickly D. All of these choices are correct.

46. What is a disadvantage of the “rubber duck” antenna supplied with most handheld radio transceivers? (T9A04) A. It does not transmit or receive as effectively as a full-sized antenna B. It transmits a circularly polarized signal C. If the rubber end cap is lost it will unravel very quickly D. All of these choices are correct.

47. How would you change a dipole to make it resonant on a higher frequency? (T9A05) A. Lengthen it B. Insert coils in series with radiating wires C. Shorten it D. Add capacity hats to the ends of the radiating wires

48. How would you change a dipole to make it resonant on a higher frequency? (T9A05) A. Lengthen it B. Insert coils in series with radiating wires C. Shorten it D. Add capacity hats to the ends of the radiating wires

49. What type of antennas are the quad, Yagi, and dish? (T9A06) A. Non-resonant antennas B. Loop antennas C. Directional antennas D. Isotropic antennas

50. What type of antennas are the quad, Yagi, and dish? (T9A06) A. Non-resonant antennas B. Loop antennas C. Directional antennas D. Isotropic antennas

51. What is a good reason not to use a “rubber duck” antenna inside of your car? (T9A07) A. Signals can be significantly weaker than when it is outside of the vehicle B. It might cause your radio to overheat C. The SWR might decrease, decreasing the signal strength D. All of these choices are correct

52. What is a good reason not to use a “rubber duck” antenna inside of your car? (T9A07) A. Signals can be significantly weaker than when it is outside of the vehicle B. It might cause your radio to overheat C. The SWR might decrease, decreasing the signal strength D. All of these choices are correct

53. What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz? (T9A08) A. 112 B. 50 C. 19 D. 12

54. What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz? (T9A08) A. 112 B. 50 C. 19 D. 12

55. What is the approximate length, in inches, of a 6 meter ½-wavelength wire dipole antenna? (T9A09) A. 6 B. 50 C. 112 D. 236

56. What is the approximate length, in inches, of a 6 meter ½-wavelength wire dipole antenna? (T9A09) A. 6 B. 50 C. 112 D. 236

57. In which direction is the radiation strongest for a half-wave dipole antenna in free space? (T9A10) A. Equally in all directions B. Off the ends of the antenna C. Broadside to the antenna D. In the direction of the feedline

58. In which direction is the radiation strongest for a half-wave dipole antenna in free space? (T9A10) A. Equally in all directions B. Off the ends of the antenna C. Broadside to the antenna D. In the direction of the feedline

59. What does an antenna tuner do? (T9B04) A. It matches the antenna system impedance to the transceiver’s output impedance B. It helps a receiver automatically tune in weak stations C. It allows the antenna to be used on both transmit and receive D. It automatically selects the proper antenna for the frequency band being used

60. What does an antenna tuner do? (T9B04) A. It matches the antenna system impedance to the transceiver’s output impedance B. It helps a receiver automatically tune in weak stations C. It allows the antenna to be used on both transmit and receive D. It automatically selects the proper antenna for the frequency band being used

61. Which of the following connectors is most suitable for frequencies above 400 MHz? (T9B06) A. A UHF (PL-259/SO-239) connector B. A Type N connector C. An RS-213 connector D. A DB-23 connector

62. Which of the following connectors is most suitable for frequencies above 400 MHz? (T9B06) A. A UHF (PL-259/SO-239) connector B. A Type N connector C. An RS-213 connector D. A DB-23 connector

63. Which of the following is true of PL-259 type coax connectors? (T9B07) A. They are good for UHF frequencies B. They are water tight C. They are commonly used at HF frequencies D. They are a bayonet type connector

64. Which of the following is true of PL-259 type coax connectors? (T9B07) A. They are good for UHF frequencies B. They are water tight C. They are commonly used at HF frequencies D. They are a bayonet type connector

65. Why should coax connectors exposed to the weather be sealed against water intrusion? (T9B08) A. To prevent an increase in feedline loss B. To prevent interference to telephones C. To keep the jacket from becoming loose D. All of these choices are correct

66. Why should coax connectors exposed to the weather be sealed against water intrusion? (T9B08) A. To prevent an increase in feedline loss B. To prevent interference to telephones C. To keep the jacket from becoming loose D. All of these choices are correct

67. What electrical difference exists between the smaller RG-58 and larger RG-8 coaxial cables? (T9B10) A. There is no significant difference between the two types B. RG-58 cable has less loss at a given frequency C. RG-8 cable has less loss at a given frequency D. RG-58 cable can handle higher power levels

68. What electrical difference exists between the smaller RG-58 and larger RG-8 coaxial cables? (T9B10) A. There is no significant difference between the two types B. RG-58 cable has less loss at a given frequency C. RG-8 cable has less loss at a given frequency D. RG-58 cable can handle higher power levels