160-meter band

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Just above the mediumwave broadcast band, 160 meters refers to the band of radio frequencies between 1800 and 2000 kHz. For many decades the lowest radio frequency band allocated for use by amateur radio, before the adoption, at the beginning of the 21st century in most countries, of the 630 and 2200 meter bands. Older amateur operators often refer to 160 meters as the Top Band[a]. It is also sometimes referred to as the "Gentleman's Band" in contrast to the often-freewheeling activity in the 80 and 20 meter bands.

History[edit]

The 160 meter band is the oldest amateur band and was the staple of reliable communication in the earliest days of amateur radio, when almost all communications were over relatively short distances. The band was allocated on a worldwide basis by the International Radiotelegraph Conference in Washington, D.C., on 4 October 1927.[1] The allocation at that time was 1715–2000 kHz. The International Radio Conference of Atlantic City reduced the allocation to 1800–2000 kHz under the provision that amateurs must not interfere with LORAN operation.[2]

As the high frequency (HF) bands were developed in mid-1920s – along with their smaller, more feasible antennas – 160 meters fell into a period of relative nonuse. Although there has always been activity on the band, fewer and fewer hams are willing (or able, due to lack of sufficient real estate) to put up the antennas necessary to take advantage of the band's unique properties. For most amateurs, the HF bands are much easier to use, and HF antennas need a lot less real estate.

After World War II, the 160 meter band was apparently not coming back. A large part of the U.S. 160 meter band was allocated on a primary basis to the LORAN radio-navigation system that began operating in and around the 160 meter band in 1942. Amateurs were relegated to secondary, non-interfering status, with severe regional power limitations and restricted day/night operations on just a few narrow segments of the band.

Many older hams recall, with no great fondness, the ear-shattering buzz-saw racket of high power LORAN stations that began in 1942 until LORAN-A was phased out in North America on 31 December 1980, and most of the world by 1985. LORAN-A was still operating in China and Japan in 1995.

Great ingenuity was used to eliminate the pulse noise of the powerful LORAN-A transmitters through such famous circuitry as the "Select-O-Ject" of the late 1950s. The technology was adapted to modern noise blanking circuits used in current amateur receivers and transceivers.

Despite many obstacles and threats from commercial and military spectrum users, the efforts of a small number of determined 160 meter operators enabled the band to survive. In the UK it was the primary band for mobile operation for many years. The band experienced a rebirth with the demise of LORAN-A in the United States in December 1980, and the removal of power restrictions below 1900 kHz soon thereafter. Power restrictions above 1900 kHz were removed in March 1984, and 160 meters was then no longer regarded as the "orphan" band, as it had been for more than half a century.[citation needed]

Technical Characteristics[edit]

Effective 160 meter operation can be particularly challenging, as full sized antennas (on the order of a quarter-wavelength or more, over 130 feet) are difficult to erect for many amateurs with limited space. Nevertheless, many radio amateurs successfully communicate over very long distances with relatively small antennas. 160 meters is populated by many highly dedicated experimenters[citation needed], as it is a proving ground for ingenuity in antenna design and operating technique.

Propagation is limited to local contacts during the day, but long distance contacts are possible at night, especially around sunrise and sunset and during periods of sunspot minima. Much about ionospheric and propagation on 160 meters is still not completely understood. Phenomena such as "chordal hop" propagation are frequently observed, as well as other unexplained long-distance propagation mechanisms. Inexplicable radio blackouts - sometimes encountered on the AM broadcast band - also occur on 160 meters. Many of these phenomena have been investigated in the scientific community also[citation needed].

Frequency allocation[edit]

The International Telecommunication Union allocated the frequencies from 1810–2000 kHz to amateur radio operations in ITU Region 1 (Europe, Greenland, Africa, the Middle East west of the Persian Gulf and including Iraq, the former Soviet Union and Mongolia) and 1800-2000 kHz in the rest of the world.[3]

See also[edit]

Notes[edit]

  1. ^ "Top band" possibly refers to the position of 2000 kHz very nearly at the top of the medium frequency band (MF); it is the highest amateur band within MF.

References[edit]

  1. ^ "International Radiotelegraph Conference" (PDF). 
  2. ^ "International Radio Conference of Atlantic City (1947)" (PDF). Archived from the original (PDF) on 10 July 2012. 
  3. ^ "Amateur HF Bands". Retrieved 28 May 2013. 

External links[edit]