Choose the right antenna

Choose the right antenna for your VHF marine radio, if you connect to the wrong antenna, even the best marine radio will not perform to their optimum. A radio needs a well-matched load (antenna) to allow the efficient conversion of electrical energy into radio waves. So we suggest you use a good quality antenna and give some of the cosiderations to you.

First, you should know the gain of your marine radio’s antenna.

When it comes to antennas, size matters - the longer the antenna, the higher the gain. Antenna gain refers to the effective increase in signal strength, achieved by the manipulation of the transmitted (or received) signal pattern. Is dB & dBd a bit familiar? It refers to the antenna gain. Because antennas work due to the principles of physics & radio wavelengths, you will generally find marine antennas in 4 common lengths :

1) shortened antennas : up to 50cms = -3dBd

2) 1/2-wave (dipole) antennas : approx. 1metre = 0dBd

3) colinear gain : approx 2.5metres = 3dBd

4) colinear high-gain : approx. 5metres+ = 5-6dBd

You can thus compare like-for-like gain antennas by checking the antenna length on the brochure - if antenna A quotes 3dB but is 1metre long & antenna B quotes 0dBd but is also 1metre long, then you know that both have similar 0dBd gain. I would be more tempted to go with antenna B as they are not trying to artificially inflate performance figures for sales purposes.