Select the best VHF antenna for my AIS

[svcheshirecat]

A good link to describe the antenna needed for a VHF AIS system is:
https://www.milltechmarine.com/VHF-Ante ... _b_32.html

Mount the antenna as high as possible (at least 2-3 meters (6-10 ft) above the water surface) and as far as practical from any existing VHF, HF or radar antennas and any metal structures (like the mast).

Antenna separation from other metal objects is by far the biggest single issue for degraded AIS performance.

Consider using an antenna splitter. Use the splitter with the highest VHF antenna that is furthest away from other metal structures. For example, on a sailboat, sharing your single VHF antenna on the top of the mast will usually work much better than a single dedicated AIS antenna installed on the stern rail.

Most VHF antennas are optimally tuned around 155-156 MHz but AIS uses frequencies around 162 MHz. If you are planning on using an antenna splitter consider matching it with the Vesper VA159 antenna or the Morad HD VHF 159 MHz Marine Antenna which are tuned at 159 MHz between the typical VHF radio frequencies and the AIS frequencies.

Check your VSWR: VSWR is Voltage Standing Wave Ratio. The higher the VSWR is, the less range you will have with your AIS and VHF radio setup. One method is to purchase a VSWR meter (such as the Shakespeare ART-3 Antenna Tester) and use it between your VHF radio and your antenna cable to check reflected power of your antenna setup.

Check cables and connectors: Antenna cables and PL259 antenna connectors can substantially impact the performance of your antenna setup.