VHF MARINE RADIO ANTENNA RANGE:

What you student's should be able to do / understand after the session:

Knowledge of:

  • Knowledge of different types of maritime VHF antennas and their different characteristics including gain, material, length and radiation patterns

Understands:

  • VHF antennas work on line of sight

Knowledge of:

  • Radio sets may have a built-in GNSS receiver or be interfaced with an external device

Knowledge of:

  • Types of batteries used to power fixed and portable VHF sets and their characteristics, charging and maintenance requirements 

Antenna Range:

Check out the RNLI's VHF information page to see their interactive VHF range calculator 

 

OR

Shakespeare Marine 'Choosing the right antenna'

VHF works on line of sight:

© Shakespeare Marine
© Shakespeare Marine

Marine VHF Radio characteristics:

  • Length: VHF antennas can range from 25 cm to 5–6 m, with the most common option for sailboats being 100 cm. 
  • Gain: The gain of an antenna is a measure of its signal strength, and is expressed in decibels (dB). A higher gain antenna has a narrower beam width and better range, but a lower gain antenna has a larger signal pattern that doesn't travel as far. 
  • Mounting: Rail, Mast, Surface etc Antennas can be mounted on the highest deck of a vessel or on the masthead of a sailboat. A flange mount can be used on a vertical or horizontal surface, while a ratchet mount can adjust to a sloped surface. 
  • Cable: The quality of the cable and connectors is important, as poor connections can lead to significant signal loss. The longer the cable, the more signal loss there will be. 
  • Colour: Fiberglass VHF antennas were previously only available in white, but some brands also offer black antennas. 
  • Collinear phased antennas: These antennas are designed to concentrate the radiated signal closer to the horizon, which can increase range and minimise fading
  • Material: Coaxial cable, copper or brass
  • Radiation patterns: Subject to antenna type, length & gain.