In the early 20th century, during the beginning of radio history, the radio spectrum was divided into three radio waves, the long (LW), the medium (MW), and the short wave (SW) band, based on their wavelengths.
Early long-distance telegraphy used long waves, with the transmitter power below 300 kHz, but it required very expensive transmitters, receivers, and huge antennas. Furthermore, long waves are also very difficult to beam directionally, resulting in loss of power over long distances.
Guglielmo Marconi conducted studies to determine the sustainability of short waves over long distances in the 1920s. Listening to distant radio stations in the medium wave AM (amplitude modulation) broadcast band was carried over to SW bands. The popularity of shortwave broadcasting began to grow rapidly all over the world, mostly set aside for international broadcasters and as a main communication tool.
This article will go over what SW radio is, shortwave radio bands, and its technology. Furthermore, this article will discuss the need for this arguably dying form of radio communication and the most common uses
What is Shortwave Radio?
Shortwave radio received its name because the wavelengths in this band are shorter than 1500 kHz, which marked the upper limit of the medium frequency band. It’s not only used by international radio stations and radio amateurs, but is a huge part of aviation, marine, diplomatic, and emergency purposes.
The simplest and most common use of shortwave radio is amplitude modulation (AM broadcast band). There are various sidebands that are tied to it and are still widely used by international broadcasters.
What is it used for?
Most commonly, SW radios are used for international broadcasting primarily by government-sponsored broadcasts, international news (like BBC World Service, founded in 1932 in the United Kingdom), or cultural shortwave stations. Amateur radio operators often use shortwave bands, after receiving the right license by the government (most likely the FCC – Federal Communications Commission).
Another common use is domestic broadcasting mostly to big populations with few longwave, mediumwave, or FM stations available to them, or for political, religious, and alternative media coverage and individual commercial paid broadcasts.
Oceanic air traffic control also uses HF bands for long-distance communications with ships that are beyond the range of traditional VHF frequencies.
A “utility station” uses shortwave radio frequencies to transmit messages not intended for the public, like marine weather, ship-to-shore shortwave stations, and more. This is exclusively for long-distance, governmental and non-broadcast communications.
A lot of amateurs have communities, sharing knowledge, news, stories, and more. And while for a listener the FM radio proves to be more efficient, and less difficult to access, the experience of using amateur radios within close-knit communities cannot be beaten. The most widely known communities can be found through websites, like the National Association for Amateur Radio (ARRL).
Listening to Shortwave Radio
Audiences around the world discovered that international, uncensored shortwave radio programming was available on the SW bands of many consumer radio receivers. Magazines, articles, and listener clubs were all involved in the golden age of SW radio. Listening to these shortwave frequency bands was especially popular during international conflicts like the Korean War, World War II, and the Persian Gulf War.
For tech-savvies and amateur radio enthusiasts, SW is one of the most exciting hobbies as a listener. Usually, the goal is to reach as many shortwave signals from as many countries as possible. Today hobbyists can listen to multiple shortwave broadcasts with remote-controlled or web-controlled receivers, even without owning a shortwave radio device.
Listeners can obtain official confirmations that document the reception of distant broadcasts (i.e. QSL cards) from broadcasters and amateur radio operators, as trophies of the hobby. Some shortwave radio stations even give out certificates, pennants, stickers, and other small tokens to their listeners.
The largest shortwave audiences tune in for broadcasts open to the general public through well-known broadcasting stations like China Radio International, Voice of America, BBC World Service, etc.
With the advent of the world wide web, most international broadcasters scaled back or completely terminated their SW transmission in favor of web-based programs. Others are moving on to digital broadcasting modes in order to achieve more efficient and high-quality transmission of SW programming. Today, computer and internet access gives any user free access to over 100 shortwave receivers without censorship or monitoring. Most SW radio broadcasters like WSPR have their own websites with stories, frequencies, channels, news, and other useful information for listeners around the world.
While most people think this technology is a dying form of radio programming, there are still a lot of advantages of shortwave radio over newer technologies.
The most commonly known advantage is the difficulty of censoring by authorities. While government authorities have no problem censoring and monitoring content on the internet, they face technical difficulties monitoring which stations are being accessed. The most well-known example of this is the attempted coup against Soviet President Mikhail Gorbachev when his access to any means of communications was limited, and the only way to stay in contact and informed was through the BBC World Service on shortwave radio frequencies.
Low-cost portable shortwave devices are widely available, and simple shortwave receivers can easily be built with only a few parts. Most newer shortwave receivers are portable and battery-operated, making shortwave communications very handy and possibly life-saving in difficult situations when reception fails (natural disasters, war zones, etc.). There are times when the internet fails, is shut off, or censored. Through SW radio, nearly every piece of information is available without the need for the internet or a computer. This medium of communication was one of the main ways of contacting anyone during times of war and disasters, so these devices are a crucial part of our history and everyday lives even today.
A lot of countries (mostly developing nations) still use shortwave radio as their main way of broadcasting any content. Shortwave radios have a larger range than FM (frequency modulation radios), and broadcasts can be easily transmitted over a distance of several thousand kilometers. Many tropical regions use shortwave radio as well, because it’s less prone to interference from thunderstorms, covers a large area, and uses low power.
Shortwave radio is one of the most robust means of communication, and can only be disrupted by interference or bad ionospheric conditions. Participants only need a pair of transceivers with antennas and a source of energy.
Disadvantages shrink in comparison to the shortwave radio’s advantages. The biggest setback of shortwave is that in most Western countries it’s only used by true enthusiasts in order to study and experiment with radio technology, as the stations that are worth listening to don’t use this wavelength and these frequencies anymore. Also, in urban areas, there are more interfering factors that make its usage difficult.
The Future of Shortwave Radio
In the past decades, SW has become digital, meaning a more efficient transmission and significant energy savings compared to the old analog. A lot of countries in Latin America use shortwave radio, the most commonly known being Argentina’s shortwave broadcasting.
The international shortwave program meant that a lot of people were able to access free information. But a lot of these international shortwave broadcasters were expensive and used a lot of energy for this frequency band that “knew no borders”, ranging from 1.7 Mhz to the end of the HF band.
To this day, BBC World Service, and many other international broadcasters are still on shortwave and have a huge audience, mainly because BBC introduced new shortwave transmissions in additional languages. Also, in Australia, there are wide consultations about reintroducing shortwave for the Pacific Islands. Radio China has also upgraded some of its shortwave transmitters to domestic use and is now covering the whole country with digital (DRM) shortwave radio signals.
DRM stands for Digital Rights Management. It was established in 1983 as Software Service System (SSS). DRM is the most suitable option for shortwave, as it has a good digital quality and reaches great distances without any fading or crackling sounds, creating a much better listening experience with higher sound quality. DRM is a systematic approach to copyright protection. The purpose of DRM is to prevent redistribution and restrict the ways consumers can copy purchased content. A DRM broadcast rivals FM quality and can also send graphic images and websites via separate information channels. While the golden age of analog shortwave broadcasting is possibly over, the band still has great potential and many important roles.
The future of SW is widely discussed. Every article has a different stand, and news about it varies. But whether an article or an expert is for or against the use of this technology, one thing always stays the same. It is undeniable that the use of such devices and currently dying technology was a huge part of our history. It has saved lives during wars, and even today, in times of disaster and worldwide conflicts, SW devices are most possibly our only hope for communication.