The marine VHF band runs from 156 MHz to 163 MHz. Most, but not all, VHF antennas send and receive over this entire band – they have sufficient bandwidth to perform at both ends of the range. But the performance, the quality of the signal, drops off towards the extremities of the range. This effect is less pronounced with top quality antennas and worryingly obvious on those of lower quality.
AIS optimised antennas were introduced to provide better performance at the higher end of the marine VHF band where the AIS signals reside – 162 MHz. But, if you want to use your AIS antenna as back up for your radio antenna you’re going to want to be sure that by optimising the performance at one end of the band you’re not going to jeopardise performance at the other end, where Channel16 resides.
Well, you can rest assured that the AIS optimised version of Metz VHF antenna has the quality of bandwidth to ensure it will perform well as a back-up radio antenna.
However, I continue to recommend that if you are ever going to use your AIS antenna to replace your radio antenna, go for the Metz Manta. If your AIS antenna is never to be used to back up your radio antenna, go for the Metz AIS optimised version.
Here’s an article on VHF antenna installation – I’m sure you’ll find it interesting and informative: VHF antenna installation