If you already have an antenna, the first step is to determine if it's suitable for AIS. Generally, any VHF antenna can receive AIS signals since they typically cover the frequency range from 30 to 300 MHz. However, it’s best to use an antenna that is specifically tuned for the AIS frequencies around 162 MHz to ensure optimal reception and range. Here you can find more details about antennas.

Ensure that the antenna is in good condition and free from any damage. If it is damaged, consider replacing it or requesting a new one, as a faulty antenna can significantly reduce reception quality. Additionally, check the type of connector (PL259 or N) on the antenna to ensure it can be properly connected with the appropriate cable.

If you do not want to use the antenna exclusively for AIS reception and if you are also using it for a radio, you will need an AIS antenna splitter.

To use your existing antenna with both a VHF radio and an AIS receiver, you'll need an AIS antenna splitter. Both devices operate on specific VHF frequencies. It's crucial to ensure that you only have an AIS receiver, not a transmitter/transceiver, as an AIS transmitter/transceiver could cause damage.

The AIS antenna splitter will enable you to use the same antenna for both your marine VHF radio and your AIS receiver. However, while the splitter allows simultaneous use, it will block AIS reception during VHF radio transmissions. Keep in mind that using a splitter generally results in reduced AIS reception compared to using the antenna exclusively for AIS.

For installation, disconnect the antenna cable from your radio and connect it to the antenna port on the splitter. The short cable labeled "VHF" should be connected to the radio.

The BNC connector labeled "AIS" should be connected to the AIS receiver.

Avoid extending the cables, as this can negatively affect reception range. The devices should be installed relatively close to each other.

Additionally, the splitter requires power. It should be connected to a power source that provides between 9 and 30 V DC and consumes approximately 0.5 watts (12V @ 35 mA). The radio will operate without power to the splitter.

Various splitters are available on the market, and the ASR-100 from Comar is a reliable example that we recommend.