Choosing a VHF Antenna for the Garmin VHF Radio

A Garmin VHF radio requires a radio antenna to be connected to allow calls to be transmitted and received by the device.

There are a few different antennas that can be used depending on the type of boat.

All antennas should use a coax cable with a resistance of 50 ohms. The length of the antenna needed will depend on the type and size of the boat.

Vessels from 16' to 25' usually use an 8' antenna.

Larger vessels may use a larger antenna with more Gain.

Most Sailboats may use a 3' - 5' antenna mounted on the masthead.

Racing Sailboats may use an 8' antenna mounted on the stern in the case of de-masting.

For safety reasons, it is a good idea to mount the antenna as high as possible on the boat.

The Gain of the antenna can also affect how the antenna operates. The maximum amount of Gain for a radio's antenna is 9dBi. Generally, the higher the gain, the better the range, though keep in mind that the higher the gain, the more compressed the beam width becomes. Narrow beams can fade in rolling seas, so small vessels should not use a gain value above 6dBi. Below is a picture illustrating the various levels of Gain and the beam width produced by each.

For more information about the VHF radio and the antenna, review the Installation Instructions.