160 meters
From Wikipedia, the free encyclopedia
Just above the mediumwave broadcast band, 160 meters is the lowest radio frequency band allotted for use by amateur radio operators in most countries. Seasoned operators refer to 160 meters as Top Band; it is also referred to sometimes as the "Gentleman's Band" in comparison to the often-freewheeling 80 and 20 meter band allocations.
Contents |
[edit] History
160 meters has an interesting history in Amateur Radio. It is one of the oldest amateur bands, and was the staple of reliable communication in the early days of Amateur Radio, when the majority of communications were relatively short distance.
As the higher frequency bands were developed, along with the associated smaller, more convenient antennas, 160 meters fell in to a period of relative disuse. Although there has always been activity on the band, fewer and fewer hams were willing to put up the sort of antennas necessary to take advantage of the band's unique properties. The H.F. bands were much easier to use, and antennas used up a lot less real estate.
Additionally, after World War II, a large part of the American 160 band was allocated on a primary basis to LORAN navigational beacons. Amateurs were relegated to secondary, non-interfering status, and regional power restrictions for the remaining sections of the band were put in place as well. Many older hams recall, with no great fondness, the ear-shattering racket of nearby LORAN stations. Great ingenuity was used to eliminate the pulse noise of the powerful beacons through such famous cicuitry as the "Select-O-Ject" of the late 1950s, the technology of which 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 the small but dedicated number of 160 operators enabled the band to survive. With the demise of LORAN, the band experienced a rebirth. The regional power restrictions were removed, and 160 is no longer regarded as the "orphan" band it was for nearly half a century.
[edit] Technical Characteristics
Effective 160 meter operation can be particularly challenging, as full sized antennas (on the order of a half-wavelength or more), are difficult to erect for many amateurs with limited space. Nevertheless, many radio amateurs successfully communicate over extremely long distances with relatively small antennas. 160 meters is populated by many hightly dedicated experimenters, as it is a proving ground for ingenuity in antenna design and operating technique.
Much about ionospheric propagation on 160 meters is still unknown. Phenomena such as "chordal hop" propagation are frequently observed on "top band" as well as several unexplained long-distance openings. Also, inexplicable radio blackouts, such as are sometimes encountered on the AM Broadcast band, can occur on 160 meters. Much speculation about these events has been put forth by the scientific community, and 160 meter operators are in a unique position to investigate such fascinating mysteries. The original "magic of radio" is very much alive and well on 160 meters.
[edit] Frequency allocation
The International Telecommunications Union allocated the frequencies from 1800 - 2000 KHz to amateur radio operations.
[edit] US Allocation Table
| US License Class | 1.800 – 2.000 |
|---|---|
| General, Advanced, Extra |
[edit] Key
| = CW, RTTY, data, phone and image |
[edit] US Band Plan
By "Gentlemen's agreement", US amateurs voluntarily limit their 160 meter emissions according to the following suggested bandplan:
| 1.800 MHz–1.830 MHz | CW, RTTY and other narrowband modes |
| 1.830 MHz–1.840 MHz | CW, RTTY and other narrowband modes, Intercontinental QSOs only |
| 1.840 MHz–1.850 MHz | CW, SSB, SSTV, other wideband modes, Intercontinental QSOs only |
| 1.850 MHz–2.000 MHz | CW, phone, SSTV and other wideband modes |
[edit] See also
- Shortwave Bands
- KN4LF 160 Meter Propagation Theory Notes. An excellent website dedicated to layman level explanations of "seemingly" mysterious 160 Meter propagation occurrences.
[edit] References
- ARRLWeb: US Amateur Bands. Retrieved on August 03, 2005.
- ARRLWeb: ARRL Band Plans. Retrieved on August 03, 2005.
- Ham Radio QRP. Retrieved on August 03, 2005.
- IARU Region 3 Bandplan. Retrieved on August 03, 2005.
| Medium (MF) and High frequency (HF) Amateur radio bands for ITU Region 2 | |||||||||
| MF | HF | ||||||||
|
|
|
||||||||
| 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 |
