What is uhf? You may have heard it before and wondered what it is.
Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 MHz and 3 GHz, also known as the decimetre band as the wavelengths range from one to ten decimetres. Radio waves with frequencies above the UHF band fall into the SHF (super-high frequency) or microwave frequency range. Lower frequency signals fall into the VHF (very high frequency) or lower bands. UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is high enough for indoor reception. They are used for television broadcasting, cordless phones, walkie-talkies, personal radio services satellite communication, cell phones and numerous other applications. The IEEE defines the UHF radar band as frequencies between 300 MHz and 1 GHz. Two other IEEE radar band overlap the ITU UHF band: the L band between 1 and 2 GHz and the S band between 2 and 4 GHz.
In this article, I’ll explain what uhf is, how it works, and some of its uses. So, let’s get started!
Propagation Characteristics of UHF Radio Waves
Propagation characteristics refer to the way radio waves travel through the air and interact with the environment. Understanding these characteristics is essential for designing and operating wireless communication systems effectively.
How do UHF Waves Travel?
UHF waves, like all radio waves, travel through the air at the speed of light. However, unlike lower frequency HF waves, UHF waves are not reflected by the ionosphere and are therefore limited to line-of-sight communication. This means that UHF waves can only travel in a straight line and are blocked by obstacles such as buildings, hills, and trees.
Power and Volume Characteristics
UHF waves have a little power and volume compared to lower frequency waves. This means that UHF signals are less able to penetrate obstacles and are more susceptible to interference from other wireless devices operating in the same frequency band.
Channel Sweep and Frequency Characteristics
UHF waves have a little channel sweep and frequency characteristics. This means that UHF channels are narrow and can only support a little bandwidth. As a result, UHF wireless communication systems are typically used for personal and shareable communications, such as walkie-talkies, wireless microphones, and remote control devices.
Antennas
Antennas are devices that enable the transmission and reception of signals. They are used to carry signals over long distances, through buildings, and around obstacles. Antennas function by converting electrical signals into electromagnetic waves and vice versa. The signals are carried through the air, and the antenna receives or transmits them.
Types of Antennas
There are different types of antennas available in the market, and each one is designed for a specific purpose. Some of the common types of antennas are:
- Omnidirectional Antennas: These antennas transmit and receive signals in all directions. They are commonly used for broadcasting television and radio signals.
- Directional Antennas: These antennas transmit and receive signals in a specific direction. They are commonly used for mobile communication and in settings where a powerful signal is required.
- Dipole Antennas: These antennas are simple and easy to set up. They are commonly found in small-scale scientific setups and are used for transmitting and receiving signals over short distances.
- Dish Antennas: These antennas employ a parabolic reflector to increase the gain of the antenna. They are commonly used for satellite communication and in settings where a powerful signal is required.
UHF vs. VHF Antennas
The choice between UHF and VHF antennas depends on the frequency of the signal and the range required. UHF antennas have a shorter wavelength and are better suited for carrying signals over shorter distances. VHF antennas have a longer wavelength and are better suited for carrying signals over longer distances.
Factors Affecting Antenna Performance
Several factors can affect the performance of an antenna, including:
- The height of the antenna: A higher antenna will enable better signal reception and transmission.
- The angle of the antenna: The angle of the antenna can affect the chance of interference and the quality of the signal.
- The sensitivity of the antenna: A more sensitive antenna will enable better signal reception.
- The power of the signal: A more powerful signal will enable better signal transmission.
- The line of sight: The antenna needs a clear line of sight to the transmitting or receiving tower.
- The setting: The antenna needs to be set up in the right location to enable clear signal transmission and reception.
- The water content in the air: Water can interfere with the signal and reduce the quality of the signal.
Antenna Gain and dB
Antenna gain is a measure of the increase in signal strength that the antenna provides. It is measured in decibels (dB). A higher gain antenna will provide a better signal than a lower gain antenna.
Simplex and Duplex Modes
Simplex mode is a mode of communication where the signal is transmitted and received on the same frequency. Duplex mode is a mode of communication where the signal is transmitted and received on different frequencies.
Repeater Antennas
Repeater antennas are used to extend the range of a signal. They receive a weak signal and retransmit it at a higher power to extend the range of the signal.
Applications
UHF is widely used in various communication applications due to its advantages over VHF. Some of the major uses of UHF in communication are:
- Public Safety: UHF is used for public safety communication, including police, fire, and emergency medical services. UHF allows for short-range communication, which is ideal for urban areas where buildings can obstruct signals. Trunked radio systems are often used to allow multiple agencies to share the same frequency channels.
- Mobile phones: UHF frequencies are used in cellular phones, including GSM and UMTS networks. These networks allow for voice and data transmission, as well as additional services such as text messaging and internet access.
- Wireless networks: UHF is used in wireless networks, including Wi-Fi and Bluetooth. These networks allow devices to be connected without the need for cords or cables.
- Satellite communication: UHF is used for satellite communication, including GPS and satellite phones. These devices allow for communication in remote areas where traditional communication methods may not be available.
Broadcasting
UHF is also used in broadcasting, including television and radio. Some of the major uses of UHF in broadcasting are:
- Television: UHF is used for digital television broadcasting, which allows for higher quality and more channels than analog broadcasting. UHF is also used for high-definition television (HDTV) broadcasting.
- Radio: UHF is used for amateur radio, also referred to as ham radio. This allows for communication between amateur radio operators using UHF frequencies. UHF is also used for cordless phones and DECT (Digital Enhanced Cordless Telecommunications) phones.
Military and Government
UHF is used by the military and government for various purposes, including:
- Land-based communication: UHF is used for land-based communication, including communication between military bases and government agencies.
- Radar and tracking: UHF is used in radars and tracking systems, including stealth technology.
- Satellite communication: UHF is used for satellite communication by the military and government.
Other Applications
UHF has many other applications, including:
- Personal radios: UHF is used in personal radios, including walkie-talkies and two-way radios. These devices are often used in outdoor activities such as camping and hiking.
- Computing devices: UHF is used in computing devices, including RFID (Radio Frequency Identification) tags and NFC (Near Field Communication) devices.
- Antennas: UHF antennas are used for transmitting and receiving UHF signals. These antennas are available in various sizes and types, including portable and base station antennas.
- Spectrum reallocation: UHF frequencies are being reallocated in order to fulfill the demand for additional spectrum for wireless services. This includes the falling demand for UHF broadcasting frequencies and the optimized use of UHF for wireless broadband services.
UHF and VHF: Who Uses Them?
Before we dive into who uses UHF and VHF frequencies, let’s have a quick understanding of what they are. UHF stands for Ultra High Frequency, and VHF stands for Very High Frequency. The main difference between the two is the frequency range they operate in. UHF radios operate in the range of 400-512 MHz, while VHF radios operate in the range of 136-174 MHz. The frequency range affects the signal range and penetration ability of the radios.
Who Uses UHF Radios?
- Construction workers: UHF radios are commonly used in construction sites due to their ability to penetrate through buildings and structures. They are also great for communicating in noisy environments.
- Industries: UHF radios are widely used in industries such as manufacturing, transportation, and logistics. They are perfect for communicating within a large area and are designed to withstand harsh environments.
- Public services: UHF radios are commonly used by public services such as police, fire, and emergency medical services. They offer a higher level of security and privacy than VHF radios.
- Commercial services: UHF radios are also used by commercial services such as stores and restaurants. They are compact and easy to carry around, making them perfect for communication within a small area.
Which One Should You Choose?
When it comes to choosing between UHF and VHF radios, there are a few things to consider:
- Signal range: UHF radios offer a shorter range but better penetration ability, while VHF radios offer a longer range but may have difficulty penetrating through buildings and structures.
- Battery life: UHF radios typically require a smaller battery size and offer longer battery life than VHF radios.
- Price: UHF radios are usually more expensive than VHF radios due to their higher frequency range and construction.
- Specific needs: Depending on your specific needs, you may find that one type of radio is better suited for you than the other.
Ultimately, the choice between UHF and VHF radios depends on the type of work you do and the environments you work in. Understanding the differences between the two can help you make an informed decision when purchasing a radio.
Choosing Between VHF and UHF Frequencies
- VHF frequencies offer a wider bandwidth, meaning they can transmit more data at once.
- VHF frequencies are better suited for outdoor use and working over longer distances.
- VHF frequencies are less prone to interference from other devices.
- VHF radios typically offer higher quality signals and are better suited for working in open areas.
Conclusion
So there you have it, uhf stands for Ultra High Frequency and it’s used for radio communication. It’s great for personal and shared communications, but not so great for long-range signals. But don’t worry, there are other frequencies for that. So, now you know!
I'm Joost Nusselder, the founder of Neaera and a content marketer, dad, and love trying out new equipment with guitar at the heart of my passion, and together with my team, I've been creating in-depth blog articles since 2020 to help loyal readers with recording and guitar tips.
