What is HF radio?

Known as the decameter band or decameter wave, high frequency (HF) is the ITU designation[1] for the range of radio frequency electromagnetic waves (radio waves) between 3 and 30 megahertz (MHz).

The HF band is a major part of the shortwave band of frequencies, so communication at these frequencies is often called shortwave radio. Because radio waves in this band can be reflected back to Earth by the ionosphere layer in the atmosphere – a method known as "skip" or "skywave" propagation – these frequencies are suitable for long-distance communication across intercontinental distances. The band is used by international shortwave broadcasting stations (2.310 - 25.820 MHz), aviation communication, government time stations, weather stations, amateur radio and citizens band services, among other uses.

Different from VHF (Very High Frequency - 30MHz-300MHz) and UHF (Ultra High Frequency - 300MHz-3GHz) radios, HF radios cover far greater distances thanks to ionospheric refraction – but the HF radio signals are prone to distortion by atmospheric conditions such as geomagnetic storms or solar flares that radio users cannot control. HF communications are best suited for long distance communication between ground operators and base stations.

What about VHF/UHF radios?

VHF radio waves operate in a band between 30-300 megahertz, while UHF radio signals are propagated within 300 megahertz and 3 gigahertz. These radio waves travel over line of sight, making them ideal for local communications over a few kilometres.

Indeed, VHF radio waves normally travel within line of sight along the Earth’s surface. Common uses for VHF are FM radio broadcasting, television broadcasting, two way land mobile radio systems (emergency, business, private use and military), long range data communication up to several tens of kilometres with radio modems, amateur radio, and marine communications. Air traffic control communications and air navigation systems (e.g. VOR, DME & ILS) work at distances of 100 kilometres or more to aircraft at cruising altitude. VHF was used for analog television stations in the US, and continues to be used for digital television.

UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception. One of the biggest pros of UHF radios is that they do a much better job of penetrating barriers in urban locations, like concrete, steel, and wood. So this kind of radio is best suited for use indoors, including buildings with multiple floors, in industries such as manufacturing, distribution, education, retail, hospitality, and healthcare. They also work well for businesses that function in both indoor and outdoor settings, where there are a lot of surrounding buildings.

Nowadays, some radios are capable of transmitting on both VHF & UHF bands, like retevis RT3S, making it meet more outdoor and indoor activities requirements. There are also some dual-band radios featuring 10W high power like , supporting a longer range of communication.

Retevis RT3S dual band ham radio

• Retevis RT3S DMR dual band handheld radio is an update to their popular and long running RT3S DMR handheld. The RT3S has some new features, most notably, the RT3S is now a dual band handheld. The RT3 was just a single band model.

  The RT3S is a tier I and tier II DMR radio, so it will work with DMR repeaters in the US. In addition to DMR digital modulation, it also has analog support with CTCSS/DCS tone encode and decode, and DTMF encoding and decoding.

  The Retevis RT82. In fact, in comparing it with the RT82, the RT3S has many of the same internal features, but lacks the IP67 waterproof designation and the roller ball interface. But with that being said, the ergonomics are very good and I do like the front panel buttons, channel selector, and volume control knob. The radio has a familiar 2 pin Kenwood style mic connector, so if you have a collection of 2 pin accessories, they should all work. Battery is a 2000 mah 7.4 volt lithium ion battery. Battery life is good, giving me all day use on a single charge.

  RT3S is now a dual band radio, so it has built-in coverage for the 136-174 Mhz VHF and 400-480 Mhz UHF bands. Of course you can only transmit where your license allows. As for new features, the RT3S has a function called lone worker. You can set the radio to signal an alarm at the push of a button if the operator is in distress. I guess this would be good in a commercial setting, but it really doesn’t have an application for amateur radio operation. The new model also supports more contacts and channels: 3000 channels and 10,000 contacts, in fact.

What’s the difference between how HF and VHF/UHF radio waves travel?

How do HF radio waves travel?

HF frequencies (between 3-30 megahertz) are transmitted from a base unit or handheld transceiver into the Earth’s atmosphere. These radio signals ‘bounce’ off the ionosphere and return to land, where they are received by another transceiver tuned into the same radio band. This form of propagation means HF radio signals can be sent and received over hundreds or even thousands of kilometres, making HF radio an excellent tool for communicating between field locations or radio base stations across wide expanses.

This form of transmission also means data propagated by HF radio is less likely to be distorted by terranean objects such as buildings or mountains.

How do VHF/UHF radio waves travel?

VHF radio waves operate in a band between 30-300 megahertz, while UHF radio signals are propagated within 300 megahertz and 3 gigahertz. These radio waves travel over line of sight, making them ideal for local communications over a few kilometres. Indeed, UHF radio frequencies best suit communications within a one kilometre radius – perfect for indoor applications.

What are the benefits of HF radio vs VHF/UHF radios?

Each mode of radio wave propagation is useful in different settings. HF radio, for example, is vital for base stations communicating with each other over vast distances, thanks to ionospheric transmission. HF radio is also useful for linking remote regions to the outside world, as HF radio communications is not reliant on conventional communications infrastructure.

Similarly, VHF/UHF radio is the perfect tool for field communications between numerous locations. As long as terranean objects such as hills or mountains don’t block the signal path, this radio wave improves communications accuracy significantly.

Barrett’s radio network interconnection options

The difference between HF and VHF/UHF transmission is application – if you build a radio communications network that gets the best out of individual devices, both HF radio and VHF/UHF radio equipment will be indispensable. However, in order to get the best out of both options, you need to seek the help of radio experts such as Barrett Communications to ensure your radio network is optimised and interconnected for peak performance.