Glomex VHF/AIS Antennas

VHF and AIS antenna basics

A dedicated VHF antenna and a dedicated AIS antenna are tuned to slightly different parts of the marine band, so while a single VHF antenna will often carry AIS traffic acceptably through a splitter, a separate AIS antenna generally gives cleaner reception, particularly on a busy boat with several transmitters aboard. Length is the main factor in gain and range: a longer antenna gives a flatter, longer-range signal pattern, which suits a stable sailing boat better than a powerboat that heels less but pitches more at speed.

Mounting height matters more than antenna choice for range, since VHF is line of sight; raising an antenna from a pushpit to a masthead can noticeably extend both transmit and receive range. Check the connector type and cable loss over the run length before ordering, as a long, thin coax run can undo much of the benefit of a taller mount.