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HF Propagations

  • 80 meters – 3.5–4.0 MHz (3500–4000 kHz) – Best at night, with significant daytime signal absorption. Works best in winter due to atmospheric noise in summer. Only countries in the Americas and few others have access to all of this band, in other parts of the world amateurs are limited to the bottom 300 kHz (or less). In the US and Canada the upper end of the sub-band from 3.6–4.0 MHz, permits use of single-sideband voice as well as amplitude modulation, voice; this sub-band is often referred to as “75 meters”.
  • 60 meters – 5 MHz region – A relatively new allocation and originally only available in a small number of countries such as the United States, United Kingdom, Ireland, Norway, Denmark, and Iceland, but now continuing to expand. In most (but not all) countries, the allocation is channelized and may require special application. Voice operation is generally in upper sideband mode and in the USA it is mandatory. The 2015 ITU World Radiocommunications Conference (WRC-15) approved a Worldwide Frequency Allocation of 5.351.5–5.366.5 MHz to the Amateur Service on a secondary basis. The allocation limits amateur stations to 15 Watts effective isotropic radiated power (EIRP); however some locations will be permitted up to 25 W EIRP.
  • 40 meters – 7.0–7.3 MHz – Considered the most reliable all-season DX band. Popular for DX at night, 40 meters is also reliable for medium distance (1500 km) contacts during the day. Much of this band was shared with broadcasters, and in most countries the bottom 100 kHz or 200 kHz are available to amateurs. However, due to the high cost of running high power commercial broadcasting facilities; decreased listener-ship and increasing competition from net based international broadcast services, many "short wave" services are being shut down leaving the 40 meter band free of other users for amateur radio use.
  • 30 meters – 10.1–10.15 MHz – a very narrow band, which is shared with non-amateur services. It is recommended that only Morse Code and data transmissions be used here, and in some countries amateur voice transmission is actually prohibited. For example, in the US, data, RTTY and CW are the only modes allowed at a maximum 200 W peak envelope power (PEP) output. Not released for amateur use in a small number of countries. Due to its location in the centre of the shortwave spectrum, this band provides significant opportunities for long-distance communication at all points of the solar cycle. 30 meters is a WARC band. "WARC" bands are so called due to the 1979 special World Administrative Radio Conference allocation of these newer bands to amateur radio use. Amateur radio contests are not run on the WARC bands.
  • 20 meters – 14.0–14.35 MHz – Considered the most popular DX band; usually most popular during daytime. QRP operators recognize 14.060 MHz as their primary calling frequency in that band. Users of the PSK31 data mode tend to congregate around 14.070 MHz. Analog SSTV activity is centered around 14.230 MHz.
  • 17 meters – 18.068–18.168 MHz – Similar to 20 meters, but more sensitive to solar propagation minima and maxima. 17 meters is a WARC band.
  • 15 meters – 21–21.45 MHz – Most useful during solar maximum, and generally a daytime band. Daytime Sporadic E propagation (1500 km) occasionally occurs on this band.
  • 12 meters – 24.89–24.99 MHz – Mostly useful during daytime, but opens up for DX activity at night during solar maximum. 12 meters is one of the WARC bands. Propagates via Sporadic E and by F2 propagation.
  • 10 meters – 28–29.7 MHz – Best long distance (e.g., across oceans) activity is during solar maximum; during periods of moderate solar activity the best activity is found at low latitudes. The band offers useful short to medium range groundwave propagation, day or night. Due to Sporadic E propagation during the late spring and most of the summer, regardless of sunspot numbers, afternoon short band openings into small geographic areas of up to 1500 km occur. Sporadic E is caused by areas of intense ionization in the E layer of the ionosphere. The causes of Sporadic E are not fully understood, but these "clouds" of ionization can provide short-term propagation from 17 meters all the way up to occasional 2 meter openings. FM operations are normally found at the high end of the band (Also repeaters are in the 29.5–29.7 MHz segment in many countries).
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