Login or Register for FREE!
Subelement D
Other Equipment
Section 19
Antennas
What are the antenna requirements of a VHF telephony coast, maritime utility or ship station?
  • Correct Answer
    The shore or on-board antenna must be vertically polarized.
  • The antenna array must be type-accepted for 30-200 MHz operation by the FCC.
  • The horizontally-polarized antenna must be positioned so as not to cause excessive interference to other stations.
  • The antenna must be capable of being energized by an output in excess of 100 watts.

§ 47 CFR 80.72 Antenna requirements for coast stations.
All emissions of a coast station a marine-utility station operated on shore using telephony within the frequency band 30-200 MHz must be vertically polarized.

§ 47 CFR 80.81 Antenna requirements for ship stations.
All telephony emissions of a ship station or a marine utility station on board ship within the frequency band 30-200 MHz must be vertically polarized.

Last edited by c.hughes. Register to edit

Tags: none

What is the antenna requirement of a radiotelephone installation aboard a passenger vessel?
  • The antenna must be located a minimum of 15 meters from the radiotelegraph antenna.
  • Correct Answer
    The antenna must be vertically polarized and as non-directional and efficient as is practicable for the transmission and reception of ground waves over seawater.
  • An emergency reserve antenna system must be provided for communications on 156.800 MHz.
  • All antennas must be tested and the operational results logged at least once during each voyage.

47 CFR Part 80, Subpart S - Compulsory Radiotelephone Installations for Small Passenger Boats

§ 47 CFR 80.923 Antenna system.
An antenna must be provided in accordance with the applicable requirements of § 80.81 of this part which is as efficient as practicable for the transmission and reception of radio waves. The construction and installation of this antenna must insure proper emergency operation.

Last edited by c.hughes. Register to edit

Tags: none

What is the most common type of antenna for GMDSS VHF?
  • Horizontally polarized circular antenna.
  • Long wire antenna.
  • Both of the above.
  • Correct Answer
    None of the above.

The most common type of GMDSS VHF antenna is a vertical whip.

Longwire antennas are normally used for HF.

VHF communications are normally vertically polarized so horizontally-polarized antennas should not be used.

Last edited by fczheng88. Register to edit

Tags: none

What is the purpose of the antenna tuner?
  • Correct Answer
    It alters the electrical characteristics of the antenna to match the frequency in use.
  • It physically alters the length of the antenna to match the frequency in use.
  • It makes the antenna look like a half-wave antenna at the frequency in use.
  • None of the above.

The antenna changes the resonant frequency of the antenna, changing its effective electrical length.

Last edited by c.hughes. Register to edit

Tags: none

What advantage does a vertical whip have over a long wire?
  • It radiates more signal fore and aft.
  • Correct Answer
    It radiates equally well in all directions.
  • It radiates a strong signal vertically.
  • None of the above.

Vertical whips are relatively non directional, and radiate well in all directions.

Last edited by c.hughes. Register to edit

Tags: none

A vertical whip antenna has a radiation pattern best described by?
  • A figure eight.
  • A cardioid.
  • Correct Answer
    A circle.
  • An ellipse.

Vertical whip antennas usually have an omnidirectional radiation pattern out to the sides, hence a circular radiation pattern.

Last edited by fczheng88. Register to edit

Tags: none

Go to 18