VHF antenna requirements

To ensure optimum antenna performance, adhere to the following guidelines:

• The use of a wideband VHF antenna is highly recommended, rather than an AIS-only antenna.

• The AIS700 requires a wideband antenna to provide good performance for both the AIS transceiver and a connected VHF radio utilizing the AIS700's integrated antenna splitter.

• Using a VHF antenna optimized for only AIS frequency operation may permanently damage the AIS700, as VHF radio transmissions are reflected back into the AIS700 due to the poor impedance match of the VHF antenna operating at VHF radio frequencies.

• Using a non-wideband VHF antenna optimized only for VHF radio frequencies may cause transmissions from the AIS transceiver to be reflected back into the AIS700, due to the poor impedance match of the antenna and AIS transceiver frequencies. Although this will not damage the AIS700 (because AIS class B transmissions are of substantially lower power than VHF transmissions), it could result in the AIS700 triggering a system VSWR alarm.

• New VHF antennas are sold with a fixed cable length. The cable length partly determines the antenna performance, and therefore cutting the cable of an antenna can affect its performance and result in a high VSWR ratio and limited reception.

Recommended VHF antenna specifications