Radio frequency is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is between the upper limit of audio frequencies and the lower limit of infrared frequencies. Different sources specify different upper and lower bounds for the frequency range. Electric currents that oscillate at radio frequencies have special properties not shared by direct current or alternating current of lower frequencies. Energy from RF currents in conductors can radiate into space as electromagnetic waves; this is the basis of radio technology. RF current does not penetrate into electrical conductors but tends to flow along their surfaces. RF currents applied to the body do not cause the painful sensation and muscular contraction of electric shock that lower frequency currents produce; this is because the current changes direction too to trigger depolarization of nerve membranes.

However this does not mean. RF current can ionize air, creating a conductive path through it; this property is exploited by "high frequency" units used in electric arc welding, which use currents at higher frequencies than power distribution uses. Another property is the ability to appear to flow through paths that contain insulating material, like the dielectric insulator of a capacitor; this is. In contrast, RF current can be blocked by a coil of wire, or a single turn or bend in a wire; this is. When conducted by an ordinary electric cable, RF current has a tendency to reflect from discontinuities in the cable such as connectors and travel back down the cable toward the source, causing a condition called standing waves. Therefore, RF current must be carried by specialized types of cable called transmission line, such as coaxial cables; the radio spectrum of frequencies is divided into bands with conventional names designated by the International Telecommunications Union: Frequencies of 1 GHz and above are conventionally called microwave, while frequencies of 30 GHz and above are designated millimeter wave.

More detailed band designations are given by the standard IEEE letter- band frequency designations and the EU/NATO frequency designations. Radio frequencies are generated and processed within many functional units such as transmitters, computers and mobile phones, to name a few. Radio frequencies are applied in carrier current systems including telephony and control circuits. RF circuit technology is used in wireless telecommunications, such as mobile communication. A typical smartphone contains a number of metal–oxide–semiconductor integrated circuit RF chips, including RF CMOS chips such as a baseband cellular modem, RF transceiver, wireless communication chips, as well as LDMOS RF power amplifiers. Radio frequency energy, in the form of radiating waves or electrical currents, has been used in medical treatments for over 75 years for minimally invasive surgeries using radiofrequency ablation including the treatment of sleep apnea. RF energy known as solid-state RF energy, is an electronic technology that uses solid-state electronics to provide RF electromagnetic radiation in a controlled manner for a wide range of applications, such as heating and home appliances.

RF energy was introduced in the 2010s, as a replacement of traditional cavity magnetron tubes used for appliances such as microwave ovens. The basis for RF energy technology is the LDMOS transistor. Common applications of LDMOS-based RF energy technology include the following. Automotive electronics Drying Heating Electric heating — RF heating microwave heating Kitchen appliances — countertop appliances, cooking appliances, RF cooking, microwave cooking, RF defrosting, frozen food defrosting, refrigerators, ovens LightingSmart lighting — RF lighting and wireless light switch Medical technology Smart appliances Test apparatus for radio frequencies can include standard instruments at the lower end of the range, but at higher frequencies the test equipment becomes more specialized. While RF refers to electrical oscillations, mechanical RF systems are not uncommon: see mechanical filter and RF MEMS. Amplitude modulation Electromagnetic interference Electromagnetic radiation Electromagnetic spectrum EMF measurement Frequency allocation Frequency bandwidth Frequency modulation Plastic welding Pulsed electromagnetic field therapy Spectrum management Definition of frequency bands IK1QFK Home Page Radio and sound waves, conversion between wavelength and frequency RF Terms Glossary

Jermaine Wattimena is a Dutch darts player who competes in Professional Darts Corporation tournaments. Wattimena won the first event he entered as he claimed the 2008 Malta Open by beating Vincent Busuttil in the final, he made his British Darts Organisation debut in a major event at the World Masters and won four games to reach the last 24 where he lost 3–0 to Steve Douglas. In 2014, Wattimena won the German Gold Cup courtesy of defeating Jan Dekker 3–2 in the final. In the year he qualified for the 2015 PDC World Championship by winning the Central European Qualifier, concluding with a 6–3 victory over Kenny Neyens. Wattimena entered the event in the preliminary round and narrowly lost 4–3 to Robert Marijanović, missing three match darts in the final leg, he entered PDC Qualifying School in January 2015 and was eliminated in the final round of the third day by Steve Douglas. However, Wattimena had done enough through the Order of Merit to not need to play on the fourth day as he finished joint second on the Order of Merit to earn a two-year PDC tour card.

He qualified for the UK Open and defeated Jonny Clayton 5–1 in the first round, but lost 5–4 against Kevin McDine. Wattimena twice lost in the last 16 of Players Championship events during the year and beat Robert Marijanović 6–5 at the European Darts Grand Prix, but was knocked out 6–3 by Peter Wright in the second round. In the first round of the 2016 World Championship, Wattimena lost 3–1 to Mensur Suljović, he overcame Andy Smith 6–5 and Kevin Dowling 6–1 at the UK Open, before losing 9–7 to Alan Norris in the third round. At the 15th Players Championship wins over Jonny Clayton, David Pallett, Peter Wright, Simon Stevenson and Jelle Klaasen ensured Wattimena played in his first PDC semi-final and he was defeated 6–3 by Michael van Gerwen, he qualified for seven European Tour events during the season and, although he didn't get past the second round in any of them, his consistent play saw him make his debut in the European Championship, where he lost 6–1 to Mensur Suljović in the first round.

He lost 3–1 in the opening round of the World Championship for the second year in a row in the 2017 event, this time to Daryl Gurney. He knocked out Mick Todd, Dave Chisnall, Robert Thornton, Kyle Anderson and Benito van de Pas at the seventh Players Championship to reach his second PDC semi-final, where he was defeated 6–3 by Kim Huybrechts, he reached third PDC semi-final in Players Championships 17, where he beat Alan Tabern, Berry van Peer, Peter Hudson, Steve Beaton and Justin Pipe, before losing to Kevin Painter 6-3. He qualified for five European Tour events over 2017, failing to make it past the Last 32 in any of them, meaning he did not qualify for the European Championships, he made a third Players Championship semi-final of the year in the final weekend in Barnsley, where he knocked out Ross Twell, Ian White, Kevin Painter, Peter Jacques and Michael Smith, before a 6-2 defeat to Adrian Lewis. This was enough for him to qualify for the Players Championship Finals, as the 29th seed.

Wattimena started off with a 6-0 hammering of Keegan Brown, where he averaged 97. He saw off Mickey Mansell 6-3 in the next round to move into his first major TV Last 16 appearance. Here, he was defeated 10-9 in a deciding leg by Steve Beaton after a superb comeback from 9-5 down, he picked up his second biggest pay cheque of his career. Wattimena's consistent improvement and progression up the rankings was rewarded with a'challenger' spot for the 2020 Premier League in Rotterdam. 2015: Preliminary round 2016: First round 2017: First round 2018: Second round 2019: Third round 2020: Second round Player profile on Jermaine Wattimena from Dartsdatabase

The Declaration of the Independence of New Zealand, signed by a number of Māori chiefs in 1835, proclaimed the sovereign independence of New Zealand prior to the signing of the Treaty of Waitangi in 1840. In 1834, James Busby, the official British Resident in New Zealand, drafted a document known as the Declaration of the Independence of New Zealand, which he and 34 northern Māori chiefs—including Tāmati Wāka Nene, Tītore and Bay of Islands brothers. By 1839, 52 chiefs had signed. In the process of signing, the chiefs established themselves as representing a confederation under the title of the "United Tribes of New Zealand". Missionaries Henry Williams and George Clarke signed as witnesses; the Declaration arose in response to concerns over the lawlessness of British subjects in New Zealand, in response to a fear that France would declare sovereignty over the islands. At this time a Frenchman, Charles de Thierry—who titled himself'Charles, Baron de Tierry, Sovereign Chief of New Zealand and King of Nuku Hiva' —was seeking to establish a colony on a 16,000-hectare plot of land he claimed to have purchased in the Hokianga.

The document arose from movements in Māori society. From 1816 onwards, a number of Northern Māori chiefs had made visits to the colonies in New South Wales and Norfolk Island, as well as to England, leading to discussions about unifying the tribes and the formation of a Māori government. Māori had become owned trading ships. In 1834, the chiefs had selected a flag for use on ships originating from New Zealand; the need for a flag of New Zealand first became clear when the merchant ship the Sir George Murray, built in the Hokianga, was seized by customs officials in the port of Sydney. The ship had been sailing without a flag—a violation of British navigation laws. New Zealand had no flag; the ship's detainment aroused indignation among the Māori population. Unless a flag was selected, ships would continue to be seized; the flag, amended when gazetted, became the first distinctively New Zealand flag. As late as 1900 it was still being used to depict New Zealand, it appeared on the South African War Medal, issued to New Zealand soldiers of the Boer War and was inscribed with the phrase "Success to New Zealand Contingent 1899–1900".

The unamended version of the flag, with eight-pointed stars and black fimbriation, is still used by Māori groups. The Declaration is displayed at the National Library of New Zealand, as part of the He Tohu exhibition, along with the Treaty of Waitangi and the 1893 Women's Suffrage Petition; the hereditary chiefs and heads of the tribes of the northern parts of New Zealand declared the constitution of an independent state. They agreed to meet in Waitangi each year to frame laws, invited the southern tribes of New Zealand to "lay aside their private animosities" and join them; the Māori text of the Declaration was made by the tino rangatira of the northern part of New Zealand and uses the term Rangatiratanga to mean independence, declaring the country a whenua Rangatira to be known as The United Tribes of New Zealand. The translation of the second paragraph is "that all sovereign power and authority in the land" should "reside and in the hereditary chiefs and heads of tribes in their collective capacity", expressed as the United Tribes of New Zealand.

The terms Kingitanga and mana were used in claiming sovereignty of the state to the assembly of the hereditary chiefs, it was declared that no government would exist except by persons appointed by the assembly of hereditary chiefs. The signatories sent a copy of the document to King William IV, asking him to act as the protector of the new state; the King had acknowledged the flag of the United Tribes of New Zealand, now recognised the Declaration in a letter from Lord Glenelg, following consideration of the Declaration by the House of Lords, dated 25 May 1836. It read, in part: The Declaration was not well received by the Colonial Office, it was decided that a new policy for New Zealand was needed as a corrective, it is notable that the Treaty of Waitangi was made between the British Crown and "the chiefs of the United Tribes of New Zealand" in recognition of their independent sovereignty. There is some debate as to. Most legal commentators argue that the claim to independence lasted only until the signing of the Treaty of Waitangi in 1840.

In 2010 the Ngāpuhi iwi in Northland requested that the Waitangi Tribunal rule on whether the tribe had in fact relinquished sovereignty in 1840 when they signed the Treaty. Historian Paul Moon has stated that the tribe is unlikely to be able to take the claim much further because "the tribe has misunderstood how treaties work."Article 2 of the Treaty of Waitangi guarantees to the chiefs their continued chieftainship, ownership of their lands and treasures. It specifies that Māori could sell land only to the Crown. Most New Zealanders consider the Treaty of Waitangi to be the nation's founding document, with formal sovereignty vested in the British Crown, but the existence of different versions of the Treaty, in both Māori and English, its brevity, leave this s