This image shows the SD12-160, a stacked dipole built for AIS and VTS base stations. It delivers 12 dBd of gain across the 155-165 MHz band and covers a 180-degree sector. This suits coastal sites facing open water. Stacking dipoles narrows the vertical beam, which concentrates energy toward the horizon where passing vessels are. Antenna Experts is a Marine Band antenna manufacturer in India that makes this VHF marine antenna for shore-based vessel traffic and tracking stations.