80-meter band
| 80-meter band | |
|---|---|
| Frequency range | 3.500–4.000 MHz (ITU Region 2, including the US) 3.500–3.800 MHz (Region 1) |
| Wavelength | About 80 m |
| Group | HF |
| US license | Technician (CW on 3.525–3.600 MHz); General and above for CW, data and voice |
| Operating | |
| Common modes | SSB (lower sideband), CW, FT8 and other digital modes, AM |
| Voice segment (US) | 3.600–4.000 MHz, often called 75 meters |
| FT8 frequency | 3.573 MHz |
| Half-wave dipole length | About 125 feet (38 m) |
| Best time | Evening and night; winter is best |
The 80-meter band, 3.500 to 4.000 MHz in the Americas, is the evening and nighttime band for regional contacts. After dark it reliably covers several hundred miles, which makes it the home of state and regional nets, late-night ragchews and a good share of emergency traffic handling. The upper, voice portion of the band is usually called 75 meters, since a signal near 3.9 MHz has a wavelength closer to 75 meters than 80, and the band as a whole is often written "80/75".
Propagation
By day, the D layer of the ionosphere absorbs most of an 80-meter signal, so daytime range is short, often a couple of hundred miles at most, and less in summer. After sunset the D layer fades and the band comes alive. Contacts of several hundred to a thousand miles or more are routine through the night, and in winter, with long nights and low noise, signals cross oceans. Intercontinental contacts are most likely along the gray line, around sunset at one end of the path and sunrise at the other.
Eighty meters is also a classic band for near-vertical incidence skywave (NVIS). A low horizontal antenna sends its signal almost straight up, and the ionosphere returns it over a circle a few hundred miles across, with no skip zone. Emergency groups use 80 meters this way in the evening and at night and 40 meters by day, changing bands as the ionosphere changes.
The band's main enemy is noise. Thunderstorms hundreds of miles away produce static crashes, known as QRN, that can make summer evenings tiring, and noise from power lines and household electronics is stronger here than on the higher bands. Winter is the quiet season.
What you'll find on the band
- 3.500–3.600 MHz is CW and the digital modes. The bottom 25 kHz is reserved for Amateur Extra licensees and is where most CW DX is found; FT8 sits at 3.573 MHz.
- 3.600–4.000 MHz is voice, on lower sideband by convention. Every evening brings a long list of state, regional and traffic nets, many of which have met on the same frequency for decades.
- AM voice, a favorite of operators who restore vintage transmitters, is also heard on 75 meters.
- Outside the Americas the band often ends at 3.800 MHz or lower, so many overseas voice stations transmit below 3.800 MHz. US General licensees, whose phone privileges begin at 3.800 MHz, can work them "split", transmitting in their own segment while listening lower.
US privileges
| License class | CW and data | Voice and image |
|---|---|---|
| Technician | 3.525–3.600 MHz (CW only, 200 W PEP) | None |
| General | 3.525–3.600 MHz | 3.800–4.000 MHz |
| Advanced | 3.525–3.600 MHz | 3.700–4.000 MHz |
| Amateur Extra | 3.500–3.600 MHz | 3.600–4.000 MHz |
CW may be used anywhere within a licensee's privileges, and General and above may run up to 1,500 watts PEP. Under Part 97, data modes are confined to 3.500–3.600 MHz. A Technician's only 80-meter privilege is Morse code between 3.525 and 3.600 MHz; voice and data need a General license. Compared with a General, the Amateur Extra class adds the bottom 25 kHz and the phone segment from 3.600 to 3.800 MHz.
Antennas
Everything on 80 meters is big. A half-wave dipole is about 125 feet long, and a full-size quarter-wave vertical about 65 feet tall, so most verticals for the band are shortened with loading coils or top hats. A dipole or inverted-V between 30 and 50 feet up is the usual antenna for regional work and NVIS; working DX takes either much more height or a vertical with a good set of radials.
The band is also wide for its frequency: 500 kHz is about 13 percent of the center frequency, and a simple dipole shows a low SWR across only part of it. Many hams cut the dipole for the end of the band they use most and add an antenna tuner for the rest. End-fed half-wave wires, sloping or bent dipoles and shortened loaded antennas fit 80 meters onto smaller lots, at some cost in efficiency. Mobile operation is possible with a large loading coil, but expect a narrow bandwidth and modest results.