are frequency allocations for use within the shortwave
radio spectrum (the upper MF band and all of the HF band). They are the
primary medium for applications such as marine communication, international
broadcasting, and worldwide amateur radio activity because they take advantage
of ionospheric propagation to send data around the world. The bands are
conventionally stated in wavelength, measured in meters. Propagation behavior
in the shortwave bands depends on the time of day, the season, and the level
of solar activity.
The band frequencies below are derived from multiple sources, and different
radios can have different numbers. Most international broadcasters use
amplitude modulation with a stepping of 5 kHz between channels; a few use
single sideband modulation.
The World Radiocommunication Conference (WRC), organized under the auspices
of the International Telecommunication Union, allocates bands for various
services in conferences every few years. The last WRC took place in 2007.
At WRC-97 in 1997, the following bands were allocated for international
||2300 - 2495 kHz
||3200 - 3400 kHz
||3900 - 4000 kHz
||shared with the North American amateur radio 80m band
||4750 - 5060 kHz
||5900 - 6200 kHz
||7200 - 7450 kHz
||shared with the amateur radio 40m band
||9400 - 9900 kHz
||Currently most heavily used band
||11,600 - 12,100 kHz
||13,570 - 13,870 kHz
||substantially used only in Eurasia
||15,100 - 15,800 kHz
||17,480 - 17,900 kHz
||18,900 - 19,020 kHz
||almost unused, could become a DRM band
||21,450 - 21,850 kHz
||25,600 - 26,100 kHz
||may be used for local DRM broadcasting
- 120m band – Mostly used locally in tropical regions, with time
stations at 2500 kHz. Notice that though this is regarded as being
shortwave, it is not in the HF band, it is in the MF band.
- 90m band – Mostly used locally in tropical regions, with limited
long-distance reception at night.
- 75m band – Mostly used in Eastern Hemisphere, not widely received
in North and South America.
- 60m band – Mostly used locally in tropical regions, though usable
at night. Time stations use 5000 kHz.
- 49m band – Good year-round night band; daytime reception is poor.
- 41m band – Reception varies by region – reasonably good night
reception, but few transmitters in this band are targeted to North America.
According to the WRC-03 Decisions on HF broadcasting, in Region 1 and 3, the
portion of 7100 kHz to 7200 kHz is reserved for amateur radio use and there
are no new broadcasting portions in this portion of the band – 7350 to
7400 kHz is newly allocated; in Regions 1 and 3, 7400 to 7450 kHz is also
allocated. This decision is effective from March 29, 2009.
- 31m band – Good year-round night band; seasonal during the day,
with best reception in winter. Time stations are clustered around 10 MHz.
- 25m band – Generally best during summer; said to be ideal during
the period before and after sunset.
- 22m band – Similar to the 19m band; best in summer.
- 19m band – Day reception good, night reception variable, best
during summer. Time stations such as WWV use 15 MHz.
- 16m band – – Day reception good, night reception varies
seasonally, with summer being the best.
- 15m band – – Seldom used.
- 13m band – Somewhat shaky day reception, very little night
reception. Similar case to 11 meters, but long distance daytime broadcasting
keeps this band active in the Asia-Pacific region.
- 11m band – This band is seldom used. Day reception tends to be
poor when the solar cycle is low but potentially excellent when the solar
cycle (generally indicated by number of sun spots) is high. Night reception
is nonexistent except for local ground wave propagation. Digital Radio
Mondiale has proposed that this band be used for local digital shortwave
broadcasts and conducted an extensive test of the concept in Mexico City in
2005. The Citizens' Band allocation in most countries is within this band.