160 meters refers to the band of radio frequencies between 1,800 and 2,000 kHz, just above the mediumwave broadcast band. 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.
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. 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.
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.
Effective operation on 160 meters can be more challenging than most other amateur bands because of the sizes involved. Full-sized antennas (on the order of a quarter-wavelength or more) are over 130 feet for monopoles, which is also the recommended height for a horizontal dipole antenna, and square half-wave loops are nearly 70 feet high. If high power is used to compensate for an under-sized antenna, even the small antenna will require a similar-sized safety zone around it, free of people and animals. That much real estate may not be feasible for many amateurs, and even with space available, erecting and securing such a large antenna is a challenge. Nevertheless, many radio amateurs successfully communicate over very long distances with relatively small antennas. 160 meters is populated by many dedicated experimenters, as it is a proving ground for ingenuity in antenna design and operating technique.
During the day propagation is limited to local contacts, 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 also encountered on the AM broadcast band – occur on 160 meters. Many of these phenomena have been investigated in the scientific community also.
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.
A website dedicated to layman level explanations of "seemingly" mysterious 160 meter (MF) propagation occurrences.
The 15-meter band (also called the 21-MHz band or 15 meters) is an amateur radio frequency band spanning the shortwave spectrum from 21 to 21.45 MHz. Almost all countries permit amateur communications on the entire band.The 15 meter band is considered a DX band (i.e., used for long-distance communications). Since signals on 15 meters propagate primarily via reflection off of the F-2 layer of the ionosphere, the band is most useful for intercontinental communication during daylight hours, especially in years close to the solar maximum. However, the band also sees long-distance openings during solar minima, and into evening hours, and does not require high-power station equipment to make contacts even at these times.
Because the 15-meter wavelength is harmonically related to that of the 40-meter band, it is often possible to use an antenna designed for 40 meters on the 15-meter band, as well.LORAN
LORAN, stand for long range navigation, was a hyperbolic radio navigation system developed in the United States during World War II. It was similar to the UK's Gee system but operated at lower frequencies in order to provide an improved range up to 1,500 miles (2,400 km) with an accuracy of tens of miles. It was first used for ship convoys crossing the Atlantic Ocean, and then by long-range patrol aircraft, but found its main use on the ships and aircraft operating in the Pacific theatre.
LORAN, in its original form, was an expensive system to implement, requiring a cathode ray tube (CRT) display. This limited use to the military and large commercial users. Automated receivers became available in the 1950s, but the same improved electronics also opened the possibility of new systems with higher accuracy. The US Navy began development of Loran-B, which offered accuracy on the order of a few tens of feet, but ran into significant technical problems. The US Air Force worked on a different concept, Cyclan, which the Navy took over as Loran-C. Loran-C offered longer range than LORAN and accuracy of hundreds of feet. The US Coast Guard took over operations of both systems in 1958.
In spite of the dramatically improved performance of Loran-C, LORAN, now known as Loran-A (or "Standard LORAN"), would become much more popular during this period. This was due largely to the large numbers of surplus Loran-A units released from the Navy as ships and aircraft replaced their sets with Loran-C. The widespread introduction of inexpensive microelectronics during the 1980s caused Loran-C receivers to drop in price dramatically, and Loran-A use began to rapidly decline. Loran-A was dismantled starting in the 1970s; it remained active in North America until 1980 and the rest of the world until 1985. A Japanese chain remained on the air until 9 May 1997, and a Chinese chain was still listed as active as of 2000.
Loran-A used the same frequencies as the amateur radio 160-meter band, and radio operators were under strict rules to operate at reduced power levels; depending on their location and distance to the shore, US operators were limited to maximums of 200 to 500 watts during the day and 50 to 200 watts at night.OpenHPSDR
The OpenHPSDR (High Performance Software Defined Radio) project dates from 2005 when Phil Covington, Phil Harman, and Bill Tracey combined their separate projects to form the HPSDR group. It is built around a modular concept which encourages experimentation with new techniques and devices (e.g. SDR, Envelope Elimination and Restoration) without the need to replace the entire set of boards. The project has expanded from the original group, and several additional people have been involved in recent HPSDR module designs.
The core modules of the project are the Atlas passive backplane, the Ozy interface which provides a USB 2.0 data channel between the HPSDR system and the host PC, and the Mercury and Penelope receiver and exciter boards, which use high speed ADCs and DACs for direct conversion of received or transmitted signals in the DC to 55 MHz frequency range.
Mercury has attracted wide interest within the HPSDR community as a general-coverage, high performance, HF receiver. It uses a 16-bit 135MSPS analog-to-digital converter that provides performance over the range 0 to 55 MHz comparable to that of a conventional analog HF radio. The receiver will also operate in the VHF and UHF range using either mixer image or alias responses. The host computer uses DSP techniques to process the digital bitstream it receives from the HPSDR system. Currently, the HPSDR hardware has been interfaced with the Flex-Radio PowerSDR Windows-based software, which is licensed under the GPL.As of February, 2011, the following HPSDR modules have been released:
Magister control board
Janus I/Q interface board
Mercury Direct Down-conversion receiver
LPU linear power supply
Excalibur frequency reference board
PennyWhistle 20 watt RF power amplifier
Hercules 100 watt RF power amplifier
Metis 1Gigbit (1000T) PC interface boardOther modules nearing release include:
Alex RX/TX filter bankReplaced by newer modules:
Ozy USB control board (replaced by Magister)
Penelope Direct Up-conversion exciter (replaced by PennyLane, not provided by TAPR but by new commercial organisation)In cooperation with the HPSDR group, TAPR has provided (or will provide) all the modules listed above. Most have been made available as either fully assembled units or as bare circuit boards; a few are available as kits of parts.
Several other modules are under development. A web site and Wiki provide further information about the HPSDR projects.
.The HPSDR project is open-source for software and uses a combination of licenses for the hardware.Yaesu FT-101
Yaesu FT-101 is a model line of modular amateur radio transceivers, built by the Yaesu Corporation in Japan during the 1970s and 1980s. FT-101 is a set that combines a solid state transmitter, receiver and a tube final amplifier. Its solid state features offer high-performance, low-current characteristics and its tube amplifier provides an almost mismatch-resistant transmitter and tuner stage. FT-101’s were made with plug-in circuit boards that could be sent to the dealer or factory for replacement or repair. Until then, modular design was unprecedented in the amateur community. This also explains the fact why so many FT-101's are still in use today. The rig was sold worldwide as Yaesu FT-101 and in Europe as Yaesu FT-101 and as Sommerkamp FT-277. Because of its reliability it earned its nickname "the workhorse".
|Range||Band||ITU Region 1||ITU Region 2||ITU Region 3|
|LF||2200 m||135.7 kHz – 137.8 kHz|
|MF||630 m||472 kHz – 479 kHz|
|160 m||1.810 MHz – 1.850 MHz||1.800 MHz – 2.000 MHz|
|HF||80 / 75 m||3.500 MHz – 3.800 MHz||3.500 MHz – 4.000 MHz||3.500 MHz – 3.900 MHz|
|60 m||5.3515 MHz – 5.3665 MHz|
|40 m||7.000 MHz – 7.200 MHz||7.000 MHz – 7.300 MHz||7.000 MHz – 7.200 MHz|
|30 m[w]||10.100 MHz – 10.150 MHz|
|20 m||14.000 MHz – 14.350 MHz|
|17 m[w]||18.068 MHz – 18.168 MHz|
|15 m||21.000 MHz – 21.450 MHz|
|12 m[w]||24.890 MHz – 24.990 MHz|
|10 m||28.000 MHz – 29.700 MHz|
|VHF||6 m||50.000 MHz – 52.000 MHz[x]||50.000 MHz – 54.000 MHz|
|4 m[x]||70.000 MHz – 70.500 MHz||N/A|
|2 m||144.000 MHz – 146.000 MHz||144.000 MHz – 148.000 MHz|
|1.25 m||N/A||220.000 MHz – 225.000 MHz||N/A|
|UHF||70 cm||430.000 MHz – 440.000 MHz||430.000 MHz – 440.000 MHz|
(420.000 MHz – 450.000 MHz)[y]
|33 cm||N/A||902.000 MHz – 928.000 MHz||N/A|
|23 cm||1.240 GHz – 1.300 GHz|
|13 cm||2.300 GHz – 2.450 GHz|
|SHF||9 cm||3.400 GHz – 3.475 GHz[y]||3.300 GHz – 3.500 GHz|
|5 cm||5.650 GHz – 5.850 GHz||5.650 GHz – 5.925 GHz||5.650 GHz – 5.850 GHz|
|3 cm||10.000 GHz – 10.500 GHz|
|1.2 cm||24.000 GHz – 24.250 GHz|
|EHF||6 mm||47.000 GHz – 47.200 GHz|
|4 mm[y]||75.500 GHz[x] – 81.500 GHz||76.000 GHz – 81.500 GHz|
|2.5 mm||122.250 GHz – 123.000 GHz|
|2 mm||134.000 GHz – 141.000 GHz|
|1 mm||241.000 GHz – 250.000 GHz|
|THF||Sub-mm||Some administrations have authorized spectrum for amateur use in this region;|
others have declined to regulate frequencies above 300 GHz, leaving them available by default.
[w] HF allocation created at the 1979 World Administrative Radio Conference. These are commonly called the "WARC bands".
|See also: Radio spectrum, Electromagnetic spectrum|