How the frequency of marine radio works

Marine radios have transmitters that send out radio waves and receivers that pick up radio waves. The radio waves produced will have a set frequency. Specific groups of frequencies behave differently. For marine radio we group frequencies as:

Very high frequency(VHF)

Medium frequency(MF)

High frequency(HF)

VHF transmissions only operate in a straight, so are ‘line of sight’. How far the VHF signal can travel is therefore dependent on the heights of the sending and receiving antennas. It is similar to how far you can see-the higher you are, the further away the horizon is. VHF transmissions can cover tens of miles. Note: VHF radios can only receive VHF transmissions.

Medium frequency transmissions are able to follow the curvature of the earth so transmissions can travel hundreds of miles. They are often used for regional broadcasting and medium range navigational aids.

HF transmissions don’t bend over the earth’s horizon, but can be bounced off the atmosphere and back down to earth. This means they have the ability to transmit and receive over great distances. Using the right frequency you can communicate globally. In reality VHF, HF and MF frequencies may exhibit behaviour similar to each other. For example, HF signals can follow the curvature of the earth like MF. But their principal characteristic is reflection off the atmosphere to achieve global communication.

The VHF, HF and MF bands can all be used on ships, and different marine radio can be purchase according to your needs. Generally speaking, VHF marine radio have two types: handheld and fixed mount, while MF and HF are both fixed mount and installed in the driver’s cab for easy operation by the crew.

If you want to know more information about marine radio, please contact us by facebook or email us: info@retevismarine.com. Also you can join the FB’s discussion group, there are many maritime radios users to discuss.