For your em-trak X100 (which combines AIS & VHF), you need a good quality antenna that is tuned for the entire VHF Marine band (including AIS), ideally 1/2 wave for better performance without a ground plane, with a PL259 connector for the X100's SO239 port.
Alongside an em-trak antenna (contact your local em-trak dealer for details), top brands like Shakespeare (e.g., Galaxy series) or Procom antennas are good choices, emphasizing proper mounting for clear sky/water view and distance from other electronics.
- Optimal Gain (3dB): A 3dB antenna provides a good balance of range and stability. Because it has a wider vertical beam, it maintains connection even when the boat rolls or pitches. For more stable vessels that heel over less (Catamarans and Motorboats), antennas with a higher gain (up to 6 dB) can be used.
- Height is Key: Since marine VHF is "line of sight," placing a 3dB antenna at the top of the mast provides a much better range (approx. 30+ miles) than a higher-gain antenna mounted lower.
If you have an unused VHF antenna from a previous radio installation that you would like to use, ensure that it meet the Key Antenna Specifications below:
- Frequency: Covers 156-162 MHz (Marine VHF & AIS) tuned to a Centre frequency of 159 MHz.
- Type: A 1/2 wave is generally better than 1/4 wave as it doesn't need a perfect ground plane.
- Connector: PL259 to fit the X100's SO239 socket.
- Gain: Higher gain (dB) means reliability at range but can be more directional; a 3dB or 6dB is standard.