Range and Coverage

Can a marine cellular antenna guarantee me coverage, with no “black spots”?

Sorry, no. A marine cellular antenna maximises your chances of being able to use your cellular phone at sea, but cannot provide service where no cellular coverage exists. The best marine cellular installation includes a car kit for the cellular phone, which will connect the antenna to the phone and keep the battery fully charged.

If antennas can only transmit and receive on a “line of sight” basis, how is it I can talk to boats which are miles away?

You are probably using a “repeater” to do this. The repeater radio sits high on a hill, and re-broadcasts your transmission. Because of the height of the repeater radio, both your antenna and the antenna on the boat you are talking to have an effective line of sight through the repeater radio.

What sort of range can I get with that antenna?

The answer depends on two things: the height of your antenna, and the height of the receiving antenna. The higher the antenna, the greater the range.  To maximise the range you can get, the antenna on your boat should be as high as possible, with a clear all round view, because VHF and Cellular transmissions are “line of sight.” If your antenna has a clear line of sight to the other antenna, then it will be able to communicate with the other antenna.

An antenna mounted on a cabin top can “see” further than if it is mounted on the deck. If your antenna has to be installed lower down, consider using a longer antenna.

Why does my antenna sometimes not work when I’m anchored in a sheltered bay?

The antenna is still working fine, but if it can’t “see” the station you are calling, you won’t hear anything. Moving the boat a few metres can make all the difference to VHF, cellular and TV coverage.

Will a high gain colinear antenna increase the range I can get?

A colinear antenna installed in the same position as a halfwave antenna will be able to contact more distant stations. However, a halfwave antenna installed on the mast will often outperform a colinear antenna installed on the deck. Height counts more than gain, and a colinear high gain antenna may not overcome the handicap of a low position. If maximum range is the key factor in your antenna selection, remember: height first, gain second.

Range Calculator

To calculate the range between two base stations, enter the height of the antenna at each station in metres for the range in nautical miles
nautical miles