HAM Technician T3

  1. What should you do if another operator reports that your station's 2 meter signals were strong just a moment ago, but now they are weak or distorted?



    D.  Try moving a few feet or changing the direction of your antenna if possible, as reflections may be causing multi-path distortion
  2. Why might the range of VHF and UHF signals be greater in the winter?



    D.  Less absorption by vegetation
  3. What antenna polarization is normally used for long-distance weaksignal CW and SSB contacts using the VHF and UHF bands?



    D.  Horizontal
  4. What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?



    D.  Signals could be significantly weaker
  5. 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?



    B.  Try to find a path that reflects signals to the repeater
  6. What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting?



    B.  Picket fencing
  7. What type of wave carries radio signals between transmitting and receiving stations?



    D.  Electromagnetic
  8. Which of the following is a likely cause of irregular fading of signals received by ionospheric reflection?



    B.  Random combining of signals arriving via different paths
  9. Which of the following results from the fact that skip signals refracted from the ionosphere are elliptically polarized?



    B.  Either vertically or horizontally polarized antennas may be used for transmission or reception
  10. What may occur if data signals arrive via multiple paths?



    A.  Error rates are likely to increase
  11. Which part of the atmosphere enables the propagation of radio signals around the world?



    B.  The ionosphere
  12. How might fog and light rain affect radio range on the 10 meter and 6 meter bands?



    D.  Fog and light rain will have little effect on these bands
  13. What weather condition would decrease range at microwave frequencies?



    C.  Precipitation
  14. What is the name for the distance a radio wave travels during one complete cycle?



    C.  Wavelength
  15. What property of a radio wave is used to describe its polarization?



    B.  The orientation of the electric field
  16. What are the two components of a radio wave?



    D.  Electric and magnetic fields
  17. How fast does a radio wave travel through free space?



    C.  At the speed of light
  18. How does the wavelength of a radio wave relate to its frequency?



    A.  The wavelength gets shorter as the frequency increases
  19. What is the formula for converting frequency to approximate wavelength in meters?



    B.  Wavelength in meters equals 300 divided by frequency in megahertz
  20. What property of radio waves is often used to identify the different frequency bands?



    D.  The approximate wavelength
  21. What are the frequency limits of the VHF spectrum?



    B.  30 to 300 MHz
  22. What are the frequency limits of the UHF spectrum?



    C.  300 to 3000 MHz
  23. What frequency range is referred to as HF?



    C.  3 to 30 MHz
  24. What is the approximate velocity of a radio wave as it travels through free space?



    C.  300,000,000 meters per second
  25. Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area?



    D.  UHF signals are usually not reflected by the ionosphere
  26. Which of the following is an advantage of HF vs VHF and higher frequencies?



    D.  Long distance ionospheric propagation is far more common on HF
  27. What is a characteristic of VHF signals received via auroral reflection?



    D.  The signals exhibit rapid fluctuations of strength and often sound distorted
  28. Which of the following propagation types is most commonly associated with occasional strong over-the-horizon signals on the 10, 6, and 2 meter bands?



    B.  Sporadic E
  29. Which of the following effects might cause radio signals to be heard despite obstructions between the transmitting and receiving stations?



    B.  Knife-edge diffraction
  30. What mode is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis?



    A.  Tropospheric ducting
  31. What band is best suited for communicating via meteor scatter?



    B.  6 meter band
  32. What causes tropospheric ducting?



    B.  Temperature inversions in the atmosphere
  33. What is generally the best time for long-distance 10 meter band propagation via the F layer?



    A.  From dawn to shortly after sunset during periods of high sunspot activity
  34. Which of the following bands may provide long distance communications during the peak of the sunspot cycle?



    D.  6 or 10 meter bands
  35. Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations?



    D.  The Earth seems less curved to radio waves than to light
Author
dcbailo
ID
352948
Card Set
HAM Technician T3
Description
Subelement T3 - Radio wave characteristics: properties of radio waves; propagation modes
Updated