1 / 44

Technician Licensing Class

Covering beam antennas, feedlines, mounting tips, common issues, and more for aspiring technicians. Developed by K3DIO and modified by SPARC.

jthiel
Download Presentation

Technician Licensing Class

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Technician Licensing Class Antennas, feedlines T9A - T9B ValidJuly 1, 2014 Through June 30, 2018 1 Developed by Bob Bytheway, K3DIO, and slightly modified by SPARC

  2. T 9 A The beam antenna concentrates signals in one direction. T9A01 2

  3. T 9 A Regarding vertical antennas, the electric field is perpendicular to the earth. T9A02 3

  4. Antennas 4

  5. T 9 A A simple dipole mounted so that the conductor is parallel to the Earth’s surface is a horizontally polarized antenna. T9A03 A disadvantage of the “rubber duck” antenna supplied with most handheld transceivers does not transmit or receive as effectively as a full sized antenna. T9A04

  6. T 9 A To change a dipole antenna to make it resonant on a higher frequency, shorten it. T9A05 The quad, Yagi, and dish antennas are directional antennas. T9A06 quad dish 6 Yagi

  7. T 9 A Signals can be significantly weaker when using a “rubber duck” antenna inside versus outside your car. T9A07 The approximate length, in inches, of a quarter-wave vertical antenna for 146 MHz is 19”. T9A08 19” 7

  8. T 9 A The approximate length of a 6-meter, halfwave wire dipole antenna is112.3 inches. T9A09 The direction of radiation is strongest from a half-wave dipole antenna in free space broadside to the antenna. T9A10 8

  9. T 9 A The increase in signal strength in a specified direction when compared to a reference antenna is referred to as the gain of an antenna. T9A11 9

  10. T 9 A A properly mounted 5/8 wavelength antenna for VHF or UHF mobile service offers a lower angle of radiation and more gain than a ¼ wavelength antenna and usually provides improved coverage. T9A12 10

  11. T 9 A VHF and UHF mobile antennas are often mounted in the center of the vehicle roof which normally provides the most uniform radiation pattern. T9A13 A type of loading when referring to an antenna is when an inductor is inserted in the radiating portion of the antenna to make it electrically longer and is called a loading coil. T9A14 11

  12. T 9 B It is important to have a low SWR in an antenna system that uses coaxial cable feed line to allow the efficient transfer of power and reduce losses. T9B01 12

  13. T 9 B The most commonly used coaxial cable in typical amateur radio installations is 50 ohm impedance.T9B02 13

  14. T 9 B Coaxial cable is used more often than any other feed line for amateur radio antenna systems due to the ease of use and it requires few special installation considerations. T9B03 14

  15. T 9 B An antenna tuner matches the antenna system impedance to the transceiver’s output impedance. T9B04 Fully auto tuner Manual tuner Icom AH4 Palstar AT5K 15

  16. T 9 B As the frequency of a signal passing through coaxial cable is increased the loss increases. T9B05 Type N connectors are most suitable for frequencies above 400 MHz. T9B06 PL-259 type coax connectors are commonly used at HF frequencies. T9B07 16

  17. T 9 B Coax connectors exposed to the weather should be sealed against water intrusion to prevent an increase in feed line loss. T9B08 Erratic changes in SWR readings might be caused by a loose connection in an antenna or a feed line T9B09. Make sure all your coaxial connections are tight to help minimize interference and erratic conditions. 17

  18. T 9 B The electrical difference existing between the smaller RG-58 and larger RG-8 coaxial cables it that the RG-8 has less loss at a give frequency. T9B10 The lowest loss at VHF and UHF type of feed line is air-insulated hardline coax. T9B11 RG-8 RG-58 18

  19. Element 2 Technician Class Question Pool T 9 A – T 9 B Valid July 1, 2014 Through June 30, 2018

  20. T9A01What is a beam antenna? An antenna built from aluminum I-beams An omnidirectional antenna invented by Clarence Beam An antenna that concentrates signals in one direction An antenna that reverses the phase of received signals 20

  21. T9A02Which of the following is true regarding vertical antennas? The magnetic field is perpendicular to the Earth The electric field is perpendicular to the Earth The phase is inverted The phase is reversed 21

  22. T9A03Which of the following describes a simple dipole mounted so the conductor is parallel to the Earth's surface? A ground wave antenna A horizontally polarized antenna A rhombic antenna A vertically polarized antenna 22

  23. T9A04What is a disadvantage of the "rubber duck" antenna supplied with most handheld radio transceivers? It does not transmit or receive as effectively as a full-sized antenna It transmits a circularly polarized signal If the rubber end cap is lost it will unravel very quickly All of these choices are correct 23

  24. T9A05 How would you change a dipole antenna to make it resonant on a higher frequency? Lengthen it Insert coils in series with radiating wires Shorten it Add capacity hats to the ends of the radiating wires 24

  25. T9A06What type of antennas are the quad, Yagi, and dish? Non-resonant antennas Loop antennas Directional antennas Isotropic antennas 25

  26. T9A07What is a good reason not to use a "rubber duck" antenna inside your car? Signals can be significantly weaker than when it is outside of the vehicle It might cause your radio to overheat The SWR might decrease, decreasing the signal strength All of these choices are correct 26

  27. T9A08What is the approximate length, in inches, of a quarter-wavelength vertical antenna for 146 MHz? 112 50 19 12 27

  28. T9A09 What is the approximate length, in inches, of a 6 meter 1/2-wavelength wire dipole antenna? 6 50 112 236 28

  29. T9A10 In which direction is the radiation strongest from a half-wave dipole antenna in free space? Equally in all directions Off the ends of the antenna Broadside to the antenna In the direction of the feedline 29

  30. T9A11What is meant by the gain of an antenna? The additional power that is added to the transmitter power The additional power that is lost in the antenna when transmitting on a higher frequency The increase in signal strength in a specified direction when compared to a reference antenna The increase in impedance on receive or transmit compared to a reference antenna 30

  31. T9A12What is a reason to use a properly mounted 5/8 wavelength antenna for VHF or UHF mobile service? It offers a lower angle of radiation and more gain than a 1/4 wavelength antenna and usually provides improved coverage It features a very high angle of radiation and is better for communicating via a repeater The 5/8 wavelength antenna completely eliminates distortion caused by reflected signals The 5/8 wavelength antenna offers a 10-times power gain over a 1/4 wavelength design 31

  32. T9A13 Why are VHF or UHF mobile antennas often mounted in the center of the vehicle roof? Roof mounts have the lowest possible SWR of any mounting configuration Only roof mounting can guarantee a vertically polarized signal A roof mounted antenna normally provides the most uniform radiation pattern Roof mounted antennas are always the easiest to install 32

  33. T9A14Which of the following terms describes a type of loading when referring to an antenna? Inserting an inductor in the radiating portion of the antenna to make it electrically longer Inserting a resistor in the radiating portion of the antenna to make it resonant Installing a spring at the base of the antenna to absorb the effects of collisions with other objects Making the antenna heavier so it will resist wind effects when in motion 33

  34. T9B01Why is it important to have a low SWR in an antenna system that uses coaxial cable feed line? To reduce television interference To allow the efficient transfer of power and reduce losses To prolong antenna life All of these choices are correct 34

  35. T9B02What is the impedance of the most commonly used coaxial cable in typical amateur radio installations? 8 ohms 50 ohms 600 ohms 12 ohms 35

  36. T9B03 Why is coaxial cable used more often than any other feedline for amateur radio antenna systems? It is easy to use and requires few special installation considerations It has less loss than any other type of feedline It can handle more power than any other type of feedline It is less expensive than any other types of feedline 36

  37. T9B04What does an antenna tuner do? It matches the antenna system impedance to the transceiver's output impedance It helps a receiver automatically tune in weak stations It allows an antenna to be used on both transmit and receive It automatically selects the proper antenna for the frequency band being used 37

  38. T9B05What generally happens as the frequency of a signal passing through coaxial cable is increased? The apparent SWR increases The reflected power increases The characteristic impedance increases The loss increases 38

  39. T9B06Which of the following connectors is most suitable for frequencies above 400 MHz? A UHF (PL-259/SO-239) connector A Type N connector An RS-213 connector A DB-25 connector 39

  40. T9B07Which of the following is true of PL-259 type coax connectors? They are preferred for microwave operation They are water tight The are commonly used at HF frequencies They are a bayonet type connector 40

  41. T9B08Why should coax connectors exposed to the weather be sealed against water intrusion? To prevent an increase in feedline loss To prevent interference to telephones To keep the jacket from becoming loose All of these choices are correct 41

  42. T9B09What might cause erratic changes in SWR readings? The transmitter is being modulated A loose connection in an antenna or a feedline The transmitter is being over-modulated Interference from other stations is distorting your signal 42

  43. T9B10What electrical difference exists between the smaller RG-58 and larger RG-8 coaxial cables? There is no significant difference between the two types RG-58 cable has less loss at a given frequency RG-8 cable has less loss at a given frequency RG-58 cable can handle higher power levels 43

  44. T9B11Which of the following types of feedline has the lowest loss at VHF and UHF? 50-ohm flexible coax Multi-conductor unbalanced cable Air-insulated hard line 75-ohm flexible coax 44

More Related