To survive in the marine environment your VHF antenna needs to be strongly built of appropriate materials – look for stainless steel components, including both the body and the whip. How the antenna is built internally isn’t so obvious – you’ll need to rely on reputation and a good warranty.
A marine VHF whip antenna depends for its performance on proper design and build-quality. That tin-can at the bottom of the antenna contains the DC shunted coil that must be precisely tuned to the proper resonance. Getting this bit of the design and build right is the difference between an antenna that performs well and one that doesn’t.
The US built Metz antenna is based on a heavy gauge stainless steel shell which encloses the coil wound around a substantial form. The coil assembly is sealed in a solid epoxy compound. This build method allows prolonged transmission without danger of coil distortion as the antenna heats up. It carries a life-time warranty.
The Metz antenna is used by professionals such as UK Search and Rescue organisations, professional fishermen, tour boats and the Clipper Round the World fleet.
Lower quality antennas have fibreglass or mild steel bodies (see picture) enclosing light gauge coils and inadequate forms all sealed in a waxy substance. This flimsy internal construction leads to distortion of the coil as the antenna heats up when transmitting, which changes the antenna characteristics, leading to poor performance.
You don’t need to pay through the nose for top quality construction: the Metz Manta, at £59.95 including UK postage, is no more expensive than ordinary antennas and lower in price than some other stainless bodied antennas. Check it out at the Salty John on-line shop.