What is shortwave?

What it is

The AM and FM stations you know are local: FM reaches about as far as the horizon, AM a few hundred kilometres, more at night. Shortwave uses higher frequencies than AM, between 3 and 30 MHz, and at those frequencies the sky itself carries the signal around the planet.

Stations gather in bands, named by their wavelength in metres: the 49-metre band is around 6 MHz, 31 metres around 9.5 MHz, 19 metres around 15 MHz. (Divide 300 by the frequency in MHz and you get the metres.) Many radios mark the bands on the dial or the display.

What you'll hear:

• International broadcasters: news, music and culture from one country to the world, often in several languages
• Religious, regional and local stations, some of them in the “tropical” bands around 5 MHz that cover whole countries
• Time signals that tick the seconds, and weather broadcasts for ships and aircraft
• Radio amateurs talking among themselves (a radio with SSB makes them readable)
• And the odd mystery, like the stations that read out only numbers

In most countries you need no licence just to listen. A radio only receives: nothing leaves it.

How it travels

From about 60 to several hundred kilometres up, the Sun's ultraviolet light turns the thin air into the ionosphere, layers of electrically charged gas. Its highest part, the F layer, bends shortwave signals back down to Earth. The ground bounces them up again, and hop by hop a signal can go around the world. A single hop can span up to about 4,000 km.

That's why the time of day matters. The rule of thumb: high bands by day, low bands by night, and the hours around sunrise and sunset, in between, are often the best of all.

The seasons change it too, and so does the Sun's 11-year cycle: more sunspots make the ionosphere stronger and open the higher bands. The current cycle peaked in October 2024. A solar flare can black out the daylit side of the Earth for minutes or hours, and a geomagnetic storm can bring the aurora and quiet the bands for a day or more. Radio Companion's Conditions screen reads all this for you, in plain words.

A short history

1. 1912

   Long waves are thought to be the only ones that travel far. In the United States, a new law leaves radio amateurs the “useless” short waves, 200 metres and below.

2. 1923

   In November, amateurs in the United States and France talk across the Atlantic on about 100 metres. Short waves, it turns out, go further with far less power.

3. 1927

   The first international broadcasts on shortwave begin, among them Philips' PCJJ from the Netherlands and an experimental station of the BBC.

4. 1931

   Vatican Radio goes on the air, built by Guglielmo Marconi.

5. 1932

   On 19 December the BBC starts its Empire Service, the forerunner of today's World Service.

6. 1939–1991

   Through the Second World War and the Cold War, shortwave carries news and propaganda across every border, and governments jam the stations they don't want heard. Millions listen: it's the golden age, and the age of the QSL card.

7. 1990s–2010s

   With satellites and the internet, many big broadcasters cut back or leave shortwave altogether.

8. 2022

   When war comes to Ukraine and news is blocked, the BBC World Service brings shortwave back for listeners in Ukraine and parts of Russia, on 5875 and 15735 kHz.

9. Today

   Fewer stations than in the golden age, but still from every continent, day and night, along with digital broadcasts (DRM), and the same thrill of a voice from far away.

Why it still matters

• Nothing in between

  No internet, SIM card, account or subscription between you and the station. A radio and batteries are all it takes, even in a blackout or after a storm.

• Across borders

  A signal from thousands of kilometres away can't be switched off at your end. That's why it matters most where news is censored.

• Private

  A radio only receives. No one, not even the station, knows you're tuned in.

• A hobby that travels

  Listeners chase faraway stations (that's DXing), send reception reports and collect the QSL cards the stations send back.

What you need

• A radio with shortwave. A portable “world-band” radio that covers about 2.3 to 26 MHz is plenty, and one with a keypad makes finding a frequency easy. SSB is a bonus, for radio amateurs. An old set from the attic works too.
• An antenna. Pull the telescopic one all the way out. By a window or outdoors is far better than deep inside a building, and a few metres of wire clipped to the antenna helps even more.
• Some quiet. LED bulbs, phone chargers, TVs, routers and solar inverters fill the bands with buzz. Run the radio on batteries and move away from them, or step outside.
• Headphones, to hear the weak ones.
• A schedule. Stations give their hours in UTC, world time, and change them twice a year: the A season starts on the last Sunday of March, the B season on the last Sunday of October. Radio Companion carries the EiBi and Aoki schedules and works out your time for you.
• A little patience. Signals come and go; that's part of the fun.

Your first night

1. Wait until after dark and sit by a window, with the antenna all the way out.
2. Start on 49 metres, between 5900 and 6200 kHz, then try 41 and 31 metres (see the table).
3. Tune slowly. Broadcasters sit every 5 kHz, so step 5 kHz at a time and pause on each.
4. Give a signal a minute. It will rise and fall (that's fading, the sky moving), and most stations say who they are on the hour or the half hour.
5. Hearing nothing? In the Americas, the time station WWV on 5, 10 or 15 MHz ticks the seconds and announces the time, so you know your radio works.
6. Write down what you hear: the time, the frequency, the language. Or catch it with Radio Companion.

The times are a guide: they shift with where you are, the season and the Sun.

Words you'll hear

kHz, MHz

Units of frequency, what your radio's display shows. 1 MHz is 1000 kHz, so 6070 kHz and 6.07 MHz are the same spot.

Band

A stretch of frequencies set aside for broadcasting, named in metres: 49 m, 31 m, 19 m.

UTC

World time, the clock the schedules use. It's London's winter time, with no daylight saving.

Propagation

How a signal travels from the station to you. Listeners call it “conditions”.

Skip

The jump a signal makes off the ionosphere, and the quiet gap it leaves: too far for the signal along the ground, too close for the first hop.

Fading

A signal's slow rise and fall as the ionosphere shifts.

DX

Distance. A DX station is a far one; DXing is chasing them.

Reception report

A letter or email to a station saying what you heard, when and how well.

SINPO, SIO

Short codes for how well you heard: Signal, Interference, Noise, Propagation and Overall, each from 1 to 5. SIO keeps three of them.

QSL

The card or letter a station sends back to confirm your report. From the radio code for “I confirm receipt”.

SSB

Single sideband, a narrow kind of transmission used by radio amateurs and ships. It needs a radio that can decode it.

DRM

Digital Radio Mondiale, digital shortwave with clear sound. It needs a DRM receiver.

Jamming

Noise transmitted on purpose to drown out a station.

A and B seasons

The schedules for the northern summer and winter, changed on the last Sundays of March and October.