We would recommend;
AIS optimised 'broadband' antennas which typically have a wider bandwidth to give improved performance at the top end of the VHF band where AIS usually operates.
Please see below for typical VHF antenna specification. If you have any doubt as to the suitability of your antenna system then please do not hesitate to contact us at support@em-trak.com and we'll be glad to help!
Typical VHF antenna specification:
Band: Marine VHF band (nominally 156MHz to 162MHz)
Impedance: 50 Ohms
Gain: 3dBi
VSWR: <1.5:1 at resonant frequency
Max power: Typically >25W
Polarisation: Vertical
Bandwidth: Typically 6MHz
Cable: RG58 or better. Note the IMO recommend RG214 or better for SOLAS installations
Connector: PL-259 (sometimes called ‘UHF’)