The 80-meter or 3.5 MHz band is a band of radio frequencies allocated for amateur radio use, from 3.5 to 4.0 MHz in IARU Region 2 (consisting mostly of North and South America), and generally 3.5 to 3.8 or 3.9 MHz in Regions 1 and 3 (the rest of the world) respectively. The upper portion of the band, which is usually used for phone (voice), is sometimes referred to as 75 meters. In Europe, 75m is a shortwave broadcast band, with a number of national radio services operating between 3.9 and 4.0 MHz. Because of high D layer absorption that persists until sunset, 80 meters is usually only good for local communications during the day, and hardly ever good for communications over intercontinental distances during the day. But it is the most popular band for regional communications networks from the late afternoon through the night time hours. At night, "80" is usually reliable for short to medium distance contacts, with average distances ranging from local contacts within 200 miles/300 km out to a distance of 1,000 miles/1,600 km or more – even worldwide – at night, depending on atmospheric and ionospheric conditions. Summary The 80-meter band is favoured for ragchews between amateurs within a range of 500 miles/800 km. During contests the band is filled with activity beginning before sunset and continuing all through the night. The 80 meter band begins at 3.5 MHz and goes up to 4.0 MHz. The upper part of the band, mostly used for voice, is often referred to as 75 meters, since the wavelength is between 80 and 75 meters. Antennas at this frequency are large: A quarter-wave vertical, for example, is approximately high. Erecting the large antennas and ensuring the antennas radiate significant power at low angles are two of the challenges facing amateurs wishing to communicate over long distances. Amateurs interested in regional communication can use low wire antennas, such as horizontal dipoles, inverted vee dipole antennas or loop antennas on this band. Horizontally polarized antennas closer than a quarter-wave to earth produce predominantly high-angle radiation, which is useful for short-distance propagation modes, such as near vertical incidence skywave. Nonetheless, with occasionally favorable propagation conditions substantial distances can still be covered with modest height antennas. 80 meters can be plagued with noise, with the rural noise floor set by propagated noise from distant thunderstorms and man-made noise sources. Urban and suburban noise