No matter what type of two-way radio you may be using, one of the most important elements of using them is the frequency being used. Nevertheless, while it is entirely possible to find the right frequencies without fully understanding what they entail, it is difficult to do so for many reasons. Either way, if you are interested in learning more about radio frequencies, you’ve come to the perfect place.
Simply put, two-way radios are radios that can both send and receive radio waves. Connected via different channels, or frequencies, all wireless communication systems use frequencies to facilitate communication. These horizontal traveling wave systems are used to transmit an electrical current, which makes the communication possible. Often called walkie-talkies, these radios are most often used as a method of communication for those who work in sectors that require constant collaborations between people working in various departments of an organization. These include industries such as transportation, emergency services, manufacturing and many others.
Frequency is the number of waves that pass a fixed point in a unit of time. Using the image above, we can see a more uniform depiction of what the term frequency is describing. The unit of time being used in that image is 1 second. We can see that the frequency represented here is 2 Hertz or 2 Hz. Hertz is the unit used to measure frequency. A Hertz refers to the amount of time it takes a wave to complete one cycle, represented above.
two way radio frequency
Now, the frequencies two-way radios utilize are much higher than our 2Hz example. We will need to think in terms of Kilo- (1,000’s) and Mega- (1,000,000’s) Hertz for the world of two-way radios.
Let’s say we are using a VHF, Very High Frequency, two-way radio system which operates in a 138 -174 Megahertz, or MHz, frequency band (or range). This means our system is sending out radio waves with a frequency of 138,000,000 – 174,000,000 Hertz per second. Crazy fast, and can you believe this is one of the lower ranges for frequency bands that two-way radios utilize?
Modern two-way radios operate using frequency bands from 134MHz up to around 900Mhz. The two-way radio systems we will look at today will be using frequency bands labeled:
Very High Frequency (VHF) ~ 138-174 MHz
Ultra High Frequency (UHF) ~ 400-512 MHz
800MHz ~ 806-824 MHz & 850-869 MHz
900MHz ~ 896-901 & 935-940 MHz
Why the variety of bands operating across such a large range of frequencies? The simple answer is lower and higher frequencies allow radios to be more specialized for different applications.
Remember how lower frequencies have longer wavelengths? This allows radios using lower frequencies to be more suitable for outdoor use over greater distances because the longer wavelengths will bend with the horizon. The lower frequencies are great for farmers, hunters, hikers, park rangers, etc., but they come at a cost of not performing as well in more urban settings. Longer wavelengths do not have much penetrating power, allowing them to bounce off the atmosphere and bend around the horizon, but this means they won’t go through dense materials like those in walls.
A radio wave with a higher frequency can more effectively go through walls and is very useful in urban settings, but the shorter wavelengths make it less useful over large distances. This is because the shorter wavelengths will penetrate straight through the atmosphere and continue in a straight fashion.
Now that we know more about how two-way radios work, let’s take a look at the two different types of frequencies. VHF and UHF:
Ultra High Frequency: Also known as UHF, Ultra High Frequencies are characterized by its high yet short wavelengths. Nevertheless, due to its high frequency, they are capable of transmitting greater energy. The applied frequency associated with UHF most often varies from 400 to 512 MHz. Its wavelength ranges between 1-5 feet. On the bright side, UHF is preferred by some because of the higher amounts of energy they transmit, as well as the fact that they are great for communicating within smaller spaces and metallic buildings, specifically.
Very High Frequency: On the other hand, VHF facilitates longer wavelengths in shorter frequencies. The optimum frequencies for VHF are 130 to 174 MHz. However, the allowable wavelength is more than 20 feet. However, the energy transmitted via VHFs is comparably lower than UHFs but the higher penetration capacity makes it possible for them to travel further distances. This frequency is preferred because they are capable of penetrating materials such as brick, glass and concrete. They also travel further while using less energy and typically have fewer transmission issues. On the other hand, these frequencies are often unable to penetrate through metallic materials. Also, the transmission energy is lower when using shorter frequencies.
Finding the right frequency for your radio is a difficult task, that is why you should trust the experts at Retevis. By doing so incorrectly, you can suffer from quality issues or the radio abruptly stopping. Our experts know whether your radio usage and situation requires UHF or VHF frequencies and how to set them properly.