80 meters
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In telecommunications, 80 meters is a shortwave radio band used by amateur radio operators. The band spans frequencies from 3.5 to 4.0 MHz, at most, although only a small number of countries permit amateur radio activity on the whole 500 kHz.
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[edit] Summary
In amateur circles, 80 meters is most heavily used for relatively local or intra-continental communication, being the favoured home of nets from the same country or region and for long ragchews between relatively local amateurs. Many amateurs use low dipoles or loops on this band, which produce predominantly high-angle radiation, which is particularly useful for using Near Vertical Incidence Skywave and other relatively short distance propagation modes. During the daytime, a station in middle or high latitudes using 100W and a single element antenna would likely have a maximum communication range of 500–800 km, perhaps extending to 1500 km for a station using a kilowatt and antennas with some gain. These ranges are lower closer to the equator due to higher solar radiation which produces D-layer absorption.
As the maximum usable frequency for long distance communication seldom sinks below 3.5 MHz anywhere on the planet, the main propagation barrier to long distance communication is heavy D-layer absorption during the daytime, ensuring that DX paths must be largely, although not entirely, in darkness. In practice, the large physical size of antennas at this frequency – a quarter-wave vertical, for example, is over 20 metres high – and the difficulty of ensuring significant low angle radiation from antennas to maximise the distance of "hops" are more important constraining factors.
At higher latitudes, a noticeable skip zone sometimes appears on the band in during darkness hours in midwinter, which can be as much as 500 km, rendering communication with some nearby stations impossible. This is not generally a problem at middle or equatorial latitudes, or for large parts of the year anywhere, but it does interfere with the heavy local wintertime traffic on the band in areas such as Northern Europe and Canada.
[edit] Frequency allocation
The International Telecommunications Union allocated the whole 500 kHz from 3.5 to 4 MHz to amateurs in the Americas, and 3.5 to 3.8 MHz to amateurs in other parts of the world. However, amateurs must share this useful piece of spectrum with other users, usually on a joint primary basis. As a result, authorities in many parts of the world can and have restricted amateur allocations.
Some allocations are as follows (in MHz):
- Argentina 3.500–3.750, 3.790–3.800
- Australia 3.500–3.700, 3.766–3.800
- Canada 3.500–4.000
- Europe 3.500–3.800
- Japan 3.500–3.575, 3.747–3.805
- New Zealand 3.500–3.900
- United States 3.500–4.000
[edit] United States bandplan
Effective 12:01 a.m. EST, December 15 2006
Maximum transmitter output power is 200 watts PEP for Novice / Technician, 1500 watts PEP for all others, regardless of frequency.
| US License Class | 3.500 – 3.525 | 3.525 – 3.600 | 3.600 – 3.700 | 3.700 – 3.800 | 3.800 – 4.000 |
|---|---|---|---|---|---|
| Novice / Technician | |||||
| General | |||||
| Advanced | |||||
| Extra |
[edit] Key
| = CW, RTTY and data (US: < 1 kHz Bandwidth) | |
| = CW, RTTY, data, MCW, test, phone and image | |
| = CW, phone and image | |
| = CW and SSB phone | |
| = CW, RTTY, data, phone and image | |
| = CW (US: Novice/Technician 200 watts PEP only) |
[edit] Band plan
[edit] United States
| 3.560 | CW QRP calling frequency |
| 3.579 | CW QRP calling frequency (colorburst crystal frequency) |
| 3.590 | RTTY/data DX (< 1 kHz Bandwidth) |
| 3.570–3.600 | RTTY/data (< 1 kHz Bandwidth) |
| 3.790–3.800 | DX window |
| 3.845 | SSTV |
| 3.885 | AM calling frequency |
| 3.985 | SSB QRP calling frequency |
[edit] See also
[edit] References
- ARRLWeb: US Amateur Bands. Retrieved on 03 August, 2005.
- ARRLWeb: ARRL Band Plans. Retrieved on 03 August, 2005.
- Ham Radio QRP. Retrieved on 03 August, 2005.
- IARU Region 3 Bandplan. Retrieved on 03 August, 2005.
| Medium (MF) and High frequency (HF) Amateur radio bands for ITU Region 2 | |||||||||
| MF | HF | ||||||||
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| 160 m | 80 m | 60 m | 40 m | 30 m | 20 m | 17 m | 15 m | 12 m | 10 m |
| 1.8 MHz | 3.5 MHz | 5 MHz | 7 MHz | 10.1 MHz | 14 MHz | 18.068 MHz | 21 MHz | 24.89 MHz | 28 MHz |
| 2 MHz | 4 MHz | region | 7.3 MHz | 10.15 MHz | 14.35 MHz | 18.168 MHz | 21.45 MHz | 24.99 MHz | 29.7 MHz |
