Marine VHF radio is one of the fundamental equipment for communication on commercial ships and watercraft. It is important and reliable for bidirectional voice communication both for ship-to-ship and ship-to-shore. To get stronger service, you should know the Marine VHF radio frequency range.
The radio uses the frequency range of 156.0 MHz to 174 MHz. By using FM channels, you can communicate faster.
A Marine VHF radio is a combination of transmitter and receiver that we can call a transceiver. The PTT (Push to talk) located on the microphone or handset monitors the mode of the radio. When you press the PTT, the radio transforms into a transmitter, and when you vellicate the PTT, the radio turns to the receiver mode.
The manufacturer’s design all the maritime VHF radios to operate either in a specific frequency or a pair of rate. In the VHF maritime mobile band, these frequencies or matching frequency pairs preserve the communication as a channel. It allows rapid and accurate tuning of the VHF. Moreover, it saves the radio operator from looking up or memorizing each frequency.
What is the range of a VHF marine radio?
The most common question people ask when they go to the market to buy a two-way radio intercom is how far they can communicate? Unfortunately, there are lots of variables involved, and so there is no easy and specific answer. A quick lesson on radio signal transmission is essential to understand the complete range of issues.
VHF radios range depends on many factors; the most remarkable of these is that VHF is mainly line-of-sight radio. Put the transmitting and receiving antennas to see each other to set up communications.
Very High Frequency (VHF) communications offer plenty of positives advantages: such as sound quality, smaller and low-cost antennas, and less subject to atmospheric noisiness.
VHF radio communication system
The wavelength of frequencies within the VHF band is about 2 m. It means that the length of the antenna (dipole antenna) for a VHF radio should not be longer than half of its width. It makes VHF communications preferably suitable for all vessels: from large passenger ships down to the smallest fishing boat.
Generally, all radio signals are not the same. They may differ in communication and reactions when they come across materials. Frequencies below 2MHz reflected off the atmosphere can follow the Earth’s curvature. As a general rule, the lower the spectrum, the higher the distance it can travel. But, low frequencies are liable to some other issues.
Most of the two-way radios used today have a frequency range within 130MHz to 900MHz (except CB & Ham radios). The two most regularly used frequency ranges for two-way radios are VHF (Very High-Frequency 130-174MHz), and UHF (Ultra High-Frequency 400-520MHz).
What is VHF?
VHF (Very high frequency) is the ITU term for the range of radiofrequency electromagnetic waves (radio waves) that are from 30 to 300 megahertz (MHz). Today’s VHF’s are not the same as those of 20 years ago.
Today the VHF is competent in sending digital messages or calling specific stations into your radio (Digital Selective Calling - DSC). They can interact with many other electronic systems containing Global Positioning System (GPS) and Automatic Identification System (AIS.) hopefully, Data transmission like email and SMS service is coming very soon.
Type of VHF Antennas
There are several types of VHF antennas on the market. Different manufacturers have made VHF antennas of several models & capacities. You can choose according to your needs. Beceselly two types of antennas are commonly found, as described below.
- Handheld Antennas
- Car, Boat, & Other Antennas
All the antennas are not the same on handheld radios. Handheld radios have two regular kinds of antennas:
- Stubby Antennas
- Whip Antennas
Car, Boat, & Other Antennas
Naturally, we can place the antenna on vehicles, on the roof, or shaft that can expand several feet above the car. Therefore, mobile radios can often converse within a range between 10 - 30 miles.
Antennas on boats are a sort of portable communication and are more the same. Except in open water, marine radios have a significant advantage; there are no obstacles! Aviation radios in the air have considerable power, since barriers as you are at a top position.
For example, a 25-watt marine radio will have a maximum range of 60 nautical miles (111 km) between two antennas mounted on tall ships. Still, that same radio will only have about 5 nautical miles (9 km) between two antennas mounted on small boats at sea level.
To conclude, we can say that the higher your antenna will be, the longer your communication range will get. Moreover, put up your antenna in a straight-up position, but not at an angle. For handheld radios, instead of a stubby antenna, get a whip antenna to increase your range.
VHF vs UHF, which is better?
VHF & UHF are the most popular frequency bands used in the two-way radios. Did papule ask me which frequency is the best VHF or UHF? Both have some advantages or disadvantages. VHF can communicate and infiltrate waves faster than UHF.
Provided VHF wave and a UHF wave were sent over an area without obstacle; the VHF wave would go almost two times faster than UHF. Even though VHF can pass through hindrance better and go farther, it is not always the better.
It's because of the difference between the VHF vs. UHF signal's reaction around structures. Remember that UHF signals are shorter than VHF. It is essential when you're in or around buildings.
Tips to Increase Your Range
- Open the ‘Monitor’ function on your radio to listen for weak signals.
- One of the easiest ways to amplify your range is to increase your height.
- If you are near the edge of your field and getting a weak signal to try to get a higher location.
- If you keep using an FRS / GMRS radio, shift to the GMRS channels.
- Make sure that your communication is set to the higher power mode.
Calculating the Horizon
The higher your antenna, the further the horizon will be. For any given height of the antenna, use the following formula: Horizon at ground level (in kilometers) = 3.569 multiply by the square root of the height of antenna (in meters). So, if the antenna height is 6 feet (1.82880 meters), multiply the horizon (3.569), equals 4.83 kilometers, or 2.99 miles away.
- Antenna Height 1.82880 meters (6 feet off the ground)
- Horizon at Ground Level x 3.569 kilometers.
- Antenna Horizon 4.83 kilometers, (or 2.99 miles) away.
However, the example stated above assumes the receiving antenna on the ground. Increasing the receiving antenna’s height would expand the line-of-site even more. So if the receiving Antenna were also 6 feet off the ground, you could be able to communicate almost 6 miles without hindrance (2.99 miles + 2.99 miles).
From the above discussion, we can see that VHF (Very High Frequency) Radio is very useful for transmitting and receiving over a long distance. Marine VHF radio is a combined transmitter and receiver that we call transceiver.
A VHF wave works two times faster than UHF if there is no hindrance between two transceivers. Even though VHF works faster than UHF, it is not suitable in all situations. VHF Radio works better if there is no obstacle between the two operators.
UHF is compatible with an environment where there is an obstruction like building or substantial element. Now you can decide which would be better for you.
There are quite a few technical inaccuracies in this article.
Regarding propagation, signals up to 15mhz regularly travel around the world in daytime regardless of the solar cycle. During solar maximum the MUF (maximum usable frequency) can go up to 30MHz. VHF below 100MHZ or so can also propagate hundreds of miles around the summer and winter solstice by skipping off of the E layer of the atmosphere. This isn’t reliable but does happen on a regular basis, especially at lower VHF.
Lastly, all radio waves travel at the speed of light regardless of frequency. Light itself is nothing but really high frequency radio waves.