Understanding the principles of radio communication begins with studying the frequency ranges, and VHF band is one of the most popular among radio amateurs and professionals. The abbreviation VHF stands for “ultra-short wave,” which covers frequencies from 30 to 300 MHz. It is in this spectrum that most modern portable radios, car transceivers and emergency response services operate, providing stable communications over short and medium distances.
The main feature of these waves is their ability to propagate within line of sight, which makes them ideal for urban areas and rough terrain. Unlike longer waves, they are less susceptible to atmospheric interference, but require more careful selection of antenna equipment. Analog modulation, often used in this range, allows voice transmission in high quality, although the digital standard DMR is gradually gaining momentum.
For a beginner, it is important to immediately understand that setting radio stations requires knowledge not only of frequencies, but also of legal restrictions. Not all frequencies in this spectrum are allowed for free use without a license. Incorrect channel selection may result in interference with emergency services or aviation, resulting in serious legal consequences. Therefore, before turning on the equipment, you need to clearly understand where you are in the frequency spectrum.
Physical properties and range characteristics
Ultrashort waves have unique physical properties that determine their behavior in the air. They practically do not go around obstacles such as hills or tall buildings, and are reflected from them, creating “dead reception” zones. That is why the installation height of the antenna plays a critical role: the higher it is located, the greater the line of sight radius and, consequently, the communication range. Wavelength in this range is from 10 to 1 meter, which allows the use of compact antenna systems.
An important aspect is the influence of weather conditions. Although rain and snow have little effect on VHF propagation, temperature inversions can cause the signal to travel unusually far, known as “long tropospheric passage.” At such moments, signals can be received hundreds of kilometers away, but this is the exception rather than the rule. For stable operation under normal conditions, it is necessary to take into account signal attenuation in wooded areas and urban areas.
Why does the signal disappear around the corner?
Ultrashort waves do not bend well around obstacles. If there is a hill or dense buildings between you and the other person, the signal may be completely blocked, even if the distance is only a couple of kilometers.
It is worth noting the difference between vertical and horizontal polarization of antennas. Walkie-talkies, which are usually held vertically, are characterized by vertical polarization. If the antenna at the base station is positioned horizontally, signal loss can reach 20 dB, which will effectively cut off the connection. The coincidence of polarization of the transmitting and receiving antennas is a prerequisite for high-quality communication.
Main subbands: FM and other types of modulation
Within the VHF spectrum, the most well-known and used is the FM subband, which in common parlance is often simply called “FM”. It covers frequencies from 65 to 108 MHz and is used for broadcasting radio stations, however, for two-way communication, radio amateurs have their own segments, for example, 144-146 MHz. Frequency modulation is used here, providing high sound quality and good immunity to static noise.
In addition to classic FM, digital modes of communication are actively developing in the ultrashort range. Standards like D-STAR, YSF and DMR allow you to transmit not only voice, but also text messages, GPS coordinates and telemetry. A digital signal is less susceptible to distortion at the edge of the reception range, but at critical attenuation it breaks off completely, while the analog signal simply becomes quieter and noisier.
The choice of frequency grid step is also important. In different countries and for different services, the step may be 6.25, 12.5 or 25 kHz. Incorrect pitch setting in the radio menu will result in you either not being able to hear the other person or causing interference on adjacent channels. Modern transceivers often have an automatic step detection function, but manual control through the menu Menu → Frequency Step remains a more reliable method.
When purchasing an antenna, pay attention to the operating frequency band. An antenna tuned to 430 MHz will perform extremely inefficiently at 145 MHz due to mismatch.
Popular frequencies and their purpose
The distribution of frequencies in the VHF range is strictly regulated to avoid chaos on the air. Radio amateurs, taxi services, security and emergency services occupy their reserved niches. Knowledge of these frequencies is necessary in order not to create interference and to find interlocutors. Below is a table of the main areas used in amateur communications.
| Range (MHz) | Title | Typical Application | Power (typical) |
|---|---|---|---|
| 144.000 - 146.000 | 2 meters | Amateur communications, repeaters | up to 100 W |
| 430.000 - 440.000 | 70 cm | Amateur communications, satellites | up to 50 W |
| 460.000 - 470.000 | LPD/PMR | Family radios, security | up to 10 W |
| 108.000 - 137.000 | Aviation | Aviation Communications (AM) | high |
Particular attention should be paid to repeater frequencies. Repeaters are repeaters installed at high elevations that significantly increase communication range. To work through them, knowledge of the frequency of reception, transmission and often the ringing tone is required CTCSS. Entering incorrect data into the channel memory will result in the repeater not opening and no one will hear you.
There are also calling frequencies that are monitored by most operators. On the 2 meter band this frequency is often 145.500 MHz. If you are in an unfamiliar area and want to get in touch, it is better to start looking for interlocutors there. However, remember that after establishing contact, it is better to free the channel by switching to the operating frequency.
Equipment: choosing a radio station and antenna
The choice of equipment for working in the VHF range depends on your purposes: mobile communications, a fixed base, or portable use on a hike. For beginner radio amateurs, popular models of handheld transceivers, such as Baofeng UV-5R or Quansheng UV-K5. They are compact, inexpensive and allow you to learn basic setup skills.
More stringent requirements are placed on vehicle and base stations. What is important here is the power of the transmitter and the quality of filtering of the adjacent channel. Professional models from brands like Motorola, Icom or Yaesu provide stable operation in difficult conditions. When choosing, you should pay attention to the availability of support for digital modes, since analogue broadcasts are gradually becoming more dense.
The antenna is half of the radio station. The efficiency of the system directly depends on the SWR (standing wave ratio). High SWR can damage the transmitter output stage. Setting up the antenna complex requires an SWR meter. The setup procedure is as follows:
- 📡 Connect the SWR meter between the radio and the antenna cable.
- 📡 Transmit a signal at different frequencies of the range and record the readings.
- 📡 Adjust the length of the antenna emitter until the SWR is minimized in the center of the work area.
- 📡 Check the reliability of all connections and insulation of connectors.
☑️ Check before departure
Operating instructions and safety
Working with radio transmitting devices requires compliance with safety precautions and etiquette. The radiation power, even in the amateur band, can be dangerous if you come into close contact with the emitter. It is strictly forbidden to turn on the transmission if the antenna is not connected or is damaged, since all the energy will go into the transmitter, causing it to overheat or breakdown.
⚠️ Warning: Never use damaged antenna cables or connectors. A spark from a poor connection can ignite fuel vapors if you are near a car or gas station.
An important aspect is maintaining radio discipline. Before broadcasting, you must listen to the channel to make sure it is free. The phrase “Receive” or “End of connection” (Over/Out) helps structure the conversation, especially in conditions of poor hearing. The use of code words and the alphanumeric alphabet (Alpha, Bravo, Charlie) increases the legibility of call signs.
The legal aspect also cannot be ignored. In most countries, operating on amateur frequencies requires obtaining a call sign and passing an exam. Operating on frequencies for official purposes (police, Ministry of Emergency Situations) without a license is strictly prohibited and is punishable by law. Always check that the frequency plan in your area is up to date as frequency allocations may change.
Safety and legality are fundamental to amateur radio communications. Following the rules protects you and keeps the airwaves clean for everyone.
Frequently asked questions (FAQ)
Is it possible to listen to the police and taxis on a regular walkie-talkie?
Technically, many modern walkie-talkies have a wide reception range, but legally listening to official conversations is often prohibited or limited. In addition, many services are moving to digital encoding, which cannot be decoded by regular civilian radio stations.
What is the communication range in the VHF range?
The range greatly depends on the terrain and the height of the antennas. In a city with a walkie-talkie it’s 1-3 km, in a field with a raised antenna - up to 10-15 km. Through a repeater, the range can reach 50-70 km or more.
Do I need a license to buy a walkie-talkie?
Purchasing equipment usually does not require a license. However, to broadcast on amateur frequencies in most countries, registration and obtaining a call sign are required. For radios in the PMR (446 MHz) and LPD bands, a license is often not required, but the power is limited.
Why does the radio get hot during long transmissions?
The signal transmission process requires a lot of energy, some of which is dissipated as heat. This is normal for powerful stations. If heating is excessive, check the antenna connection (SWR) and reduce the power or duration of transmissions.