AIS Antenna

[martinriches]

Winter job number 15; fit a AIS antenna onto coach roof of my mobo. Coach roof about 2.5m above water.I am wondering what length antenna do I need. We are misplacement speed and I am considering something about 1m. Would that give me enough range?

Is it worthwhile going for a AIS antenna or would a standard VHF do?


Martin

 

[Episode]

Any decent VHF antenna will suffice. You are limited to line of sight (or there abouts) and the height of your antenna and that of the transmitting station will be the things that limit the range.

Longer antennas generally have a higher gain (you will usually find this in the spec and is measured in Db) and produce a narrower beam. This focues the power and can theoretcially result in longer range (but not beyond line of sight). However, a narrow beam also can limit performance if the vessel rolls - the narrow beam points at the sea and the sky, a wider beam still covers the horizon.

Others may have more scientific view but this is my understanding.

Hope this helps.