What is shortwave radio?

How does shortwave travel so far?

Shortwave bends back to Earth in the ionosphere, layers of charged gas 50 to 400 km and more above the ground. One hop off the highest layer, F2, covers up to about 4,000 km. The ground and the sea send the signal back up, so it can hop around the globe.5

The layers are peaks of ionization, not hard shells. They change with the Sun, which is why shortwave behaves differently by day and by night.5

Source: Ian Poole, G3YWX, in the ARRL's QST.5

Between the end of the ground wave and the first signal that comes back from the sky lies the skip zone, where nothing is heard. On shortwave it can be a thousand miles wide or more. Raise the frequency far enough and the signal no longer bends back: it goes through the layers into space.5

Why does shortwave change between day and night?

By day the D layer soaks up the lower frequencies, so frequencies below about 10 MHz travel best at night and those above 10 MHz by day. How high you can go depends on the Sun: over its 11-year cycle the upper bands open and close.56

• Maximum usable frequency (MUF). The highest frequency that still bends back between two places. The best working frequency is about 85% of it, and transmitter power does not change it.7
• The solar cycle. Near the low point of the cycle, bands above about 20 MHz may not work at all. Near the peak, even 50 MHz can. NASA and NOAA announced on October 15, 2024 that the Sun had reached the maximum phase of Solar Cycle 25.589 In NOAA's data the smoothed sunspot number peaked at 160.9 in October 2024 and had dropped to 94.4 by March 2026; the month of the peak is only fixed in hindsight.108
• Solar flux (F10.7). Radio noise from the Sun at 10.7 cm, a simple measure of solar activity. It runs from below 50 to above 300 units over a cycle and tracks the ultraviolet that charges the ionosphere.11
• K and Kp index. Disturbance of the Earth's magnetic field, 0 to 9. Kp 5 or more is a geomagnetic storm.12

When the Sun misbehaves, NOAA rates the effect on shortwave on two scales:1314

Shortwave bands and frequencies

International broadcasters work in ten bands between 5.9 and 26.1 MHz, set by the ITU, the UN agency for radio. Listeners call them by wavelength: the 49-meter band is 5.9–6.2 MHz, the 31-meter band 9.4–9.9 MHz. Below 5.1 MHz there are bands for national broadcasting, most of them only in the tropics.23

Source: ITU, bands allocated to broadcasting; band names by convention.23

Broadcasters change frequencies twice a year. Season A runs from the last Sunday in March, season B from the last Sunday in October. The summer schedule A26 ends on October 25, 2026, when B26 begins.15 Ham bands sit between the broadcast bands; they are on the ham radio page.

What can you hear on shortwave?

International broadcasters, time signals, aircraft over the oceans, ships, weather charts, hams and numbers stations. Broadcasting has shrunk: by HFCC counts, international shortwave fell from 107,210 hours a week in 2010 to 61,538 in winter 2025/26, a drop of 43%.15

Some big names have left. Deutsche Welle dropped shortwave in German, Russian, Persian and Indonesian on November 1, 2011, Radio Canada International on June 24, 2012, and Radio Australia on January 31, 2017; the BBC Russian service went off shortwave in 2011.2324425 In March 2025 the US Agency for Global Media shut down its broadcasters; Radio Martí's shortwave went silent, and in January 2026 a former VOA correspondent counted only minutes a day of VOA on shortwave.2122

What is on the air at this minute, by language and area, is in What's on shortwave now.

Why broadcasters stay: in the HFCC's words, shortwave is the only platform that does not need the consent of the country it covers, and a listener cannot be identified.15

What are numbers stations?

Shortwave stations that read out groups of numbers, mostly in a synthetic voice, believed to carry encrypted messages to intelligence officers abroad. No government admits running one. US court records come closest: they describe Cuban intelligence sending encrypted radio messages to its agents, received on shortwave.333738

• UVB-76, "The Buzzer". On 4625 kHz around the clock, a short buzz about 25 times a minute, now and then a live voice in Russian reading a message. The earliest kept recording is from 1982. The name is a misreading of the call sign UZB76; since the end of 2020 it has been NZhTI. No official has confirmed what it is for.3536
• The Lincolnshire Poacher. A British station, mid-1970s to July 2008: bars of the English folk tune, then a woman's voice reading groups of five numbers. Widely attributed to MI6, never confirmed.34
• Cuba's Atención. The first numbers station publicly accused of sending to spies, at the 2001 Wasp Network trial. In 2009 the US Justice Department charged that a former State Department official had received coded messages from Cuba on a shortwave radio.3337

Numbers stations are still on air. The Summer 2026 schedule by EiBi lists the Buzzer and stations it labels E11 (Polish) and E06 and E07 (Russian); those labels are hobbyists' attributions.18

What radio do you need for shortwave?

Any receiver that covers 3–30 MHz. A portable world-band radio with a telescopic antenna hears the big broadcasters. To hear hams, aircraft or ships you need SSB: a plain AM radio cannot make single-sideband voice readable.394047

A few broadcasters, Radio Romania International and CRI among them, also send digital shortwave (DRM), which needs a DRM-capable receiver.3918

What antenna works for shortwave?

Start with the telescopic antenna, then add a length of wire outside. Listeners often use a random wire, any length, strung outdoors away from electrical noise. Below about 14 MHz, where noise is the limit, small loop antennas are common; a loop has a sharp null in one direction.414742

• Noise is the real enemy. The ARRL lists power lines, solar installations, LED lighting and household electronics among the sources of radio interference it deals with.43
• Lightning. An outdoor wire needs a way to disconnect the radio and ground the antenna before storms.4441

DXing, reception reports and QSL cards

DXing is hunting distant stations: DX is old telegraph shorthand for distance. Listeners send stations a reception report with time, frequency and a SINPO score, and many stations confirm it with a QSL card or an e-mail.454746

SINPO rates Signal, Interference, Noise, Propagation and Overall from 1 to 5, a code from 1951. Radio Romania International still prints reports such as "SINPO 45544" in 2026.4619 Utility stations answer too: Canada's NRC asks for reports on CHU, and AirNav Ireland has a QSL page for Shanwick and Shannon.2859

Check what you heard against a schedule, and keep EiBi's warning in mind: "The ONLY 100% ID is that which you hear on the radio yourself."17

Shortwave listening clubs and references

Before the internet, clubs were how listeners swapped logs and schedules, and a few still run. The printed handbook WRTH ends with its 2026 edition, while free schedules such as EiBi are updated every season.50515316

Do you need a license to listen to shortwave?

Licenses are about transmitting; a shortwave receiver only listens. The UK's 1989 receiver regulations, for example, exempted equipment that cannot transmit, except TV sets and sets used to hear unlicensed pirate stations. Rules differ by country, so check your own.57

To talk back you need a ham license and a transceiver. Shortwave listening and ham radio share the same range but use different bands. The differences are on What is ham radio?, and how to get licensed in 14 countries is on How to get a ham radio license.

Is shortwave still useful in an emergency?

Yes, because it needs nothing between the transmitter and your radio. When local networks are down or blocked, broadcasters switch shortwave back on: the HFCC calls it often the only source of news in disaster areas.15

For two-way emergency radio, see What is ARES?.

Can a PoC radio receive shortwave?

No. A PoC radio talks over the mobile network through a push-to-talk app and has no shortwave receiver. The two work the opposite way: shortwave needs no network but only listens, while PoC talks both ways wherever there is mobile coverage. See What is a PoC radio? and types of two-way radio.

Questions

Sources

1. Recommendation ITU-R V.431-8: nomenclature of the frequency and wavelength bands (2015) · ITU (web archive copy)
2. Frequency bands allocated to terrestrial broadcasting services · ITU
3. Shortwave radio · Wikipedia
4. Shortwave radio, chapter 1 (Senate committee report) · Parliament of Australia
5. Radio waves and the ionosphere, QST, November 1999 · ARRL, Ian Poole G3YWX
6. Skywave · Wikipedia
7. Maximum usable frequency · Wikipedia
8. NASA, NOAA: Sun reaches maximum phase in 11-year solar cycle (October 15, 2024) · NASA
9. Joint solar maximum announcement · NOAA Space Weather Prediction Center
10. Observed solar cycle indices (data) · NOAA Space Weather Prediction Center