An antenna is an antenna is an antenna, right? Not necessarily. If you’re an avid boater, you likely (and hopefully) utilize a VHF — or “very high frequency” — radio. Typically, VHF radios utilize a single, VHF antenna. However, more boaters are finding that Automatic Identification System antennas are an increasingly helpful tool for navigating the waters. The problem is that most VHF radios only allow one antenna input, which leaves boaters wondering, which type of antenna should they use: VHF vs AIS antennas?
Single Purpose vs. Dual Purpose AIS
First things first — if you’re not sure whether you should use a VHF antenna or an AIS, consider whether the antenna in question is receive-only or receive/transmit. Knowing the answer to this is half the battle.
If an AIS antenna receives and transmits information, it will feature an internal splitter. However, it will have a single antenna input, which you would insert into your VHF radio. In this case, you will want to get an antenna labeled as “VHF.”
If, however, an AIS antenna is a true AIS antenna — meaning it receives information only — you should only invest in it if you have a second antenna input on a different radio. This is because AIS does not transmit your location, which can prove disastrous as a boater. When it comes to the VHF vs AIS antennas battle, VHF wins out, as it transmits boaters’ locations, which is the most critical piece of communication people out at sea can broadcast.
When Boats Have a Transmit/Receive Setup
You may wonder what you should do if your boat is set up with a transponder that allows a single-use radio to serve a dual purpose. Is it okay, then, to equip your radio with one true AIS and one true VHF? While this might seem like the ideal solution, the fact is that AIS and VHF require different frequencies. Even if you attached two true antennas to your radio, one would perform more poorly than the other. You do not want that one to be your VHF.
While it may be tempting to condense the equipment on your boat by investing in a dual-purpose antenna, or by combining antennas with a splitter, refrain from doing so. VHF antennas save lives, so it’s important to always have a true VHF onboard.