Coaxial cable, or coax is a type of electrical cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Many coaxial cables have an insulating outer sheath or jacket; the term coaxial comes from the outer shield sharing a geometric axis. Coaxial cable was used in the first and following transatlantic cable installations, but its theory wasn't described until 1880 by English physicist and mathematician Oliver Heaviside, who patented the design in that year. Coaxial cable is a type of transmission line, used to carry high frequency electrical signals with low losses, it is used in such applications as telephone trunklines, broadband internet networking cables, high speed computer data busses, carrying cable television signals, connecting radio transmitters and receivers to their antennas. It differs from other shielded cables because the dimensions of the cable and connectors are controlled to give a precise, constant conductor spacing, needed for it to function efficiently as a transmission line.
Coaxial cable is used as a transmission line for radio frequency signals. Its applications include feedlines connecting radio transmitters and receivers to their antennas, computer network connections, digital audio, distribution of cable television signals. One advantage of coaxial over other types of radio transmission line is that in an ideal coaxial cable the electromagnetic field carrying the signal exists only in the space between the inner and outer conductors; this allows coaxial cable runs to be installed next to metal objects such as gutters without the power losses that occur in other types of transmission lines. Coaxial cable provides protection of the signal from external electromagnetic interference. Coaxial cable conducts electrical signal using an inner conductor surrounded by an insulating layer and all enclosed by a shield one to four layers of woven metallic braid and metallic tape; the cable is protected by an outer insulating jacket. The outside of the shield is kept at ground potential and a signal carrying voltage is applied to the center conductor.
The advantage of coaxial design is that with differential mode, equal push-pull currents on the inner and outer conductors, the signal's electric and magnetic fields are restricted to the dielectric, with little leakage outside the shield. Further and magnetic fields outside the cable are kept from interfering with signals inside the cable, if unequal currents are filtered out at the receiving end of the line; this property makes coaxial cable a good choice both for carrying weak signals, that cannot tolerate interference from the environment, for stronger electrical signals, that must not be allowed to radiate or couple into adjacent structures or circuits. Larger diameter cables and cables with multiple shields have less leakage. Common applications of coaxial cable include video and CATV distribution, RF and microwave transmission, computer and instrumentation data connections; the characteristic impedance of the cable is determined by the dielectric constant of the inner insulator and the radii of the inner and outer conductors.
In radio frequency systems, where the cable length is comparable to the wavelength of the signals transmitted, a uniform cable characteristic impedance is important to minimize loss. The source and load impedances are chosen to match the impedance of the cable to ensure maximum power transfer and minimum standing wave ratio. Other important properties of coaxial cable include attenuation as a function of frequency, voltage handling capability, shield quality. Coaxial cable design choices affect physical size, frequency performance, power handling capabilities, flexibility and cost; the inner conductor might be stranded. To get better high-frequency performance, the inner conductor may be silver-plated. Copper-plated steel wire is used as an inner conductor for cable used in the cable TV industry; the insulator surrounding the inner conductor may be solid plastic, a foam plastic, or air with spacers supporting the inner wire. The properties of the dielectric insulator determine some of the electrical properties of the cable.
A common choice is a solid polyethylene insulator, used in lower-loss cables. Solid Teflon is used as an insulator, in plenum-rated cables; some coaxial lines have spacers to keep the inner conductor from touching the shield. Many conventional coaxial cables use braided copper wire forming the shield; this allows the cable to be flexible, but it means there are gaps in the shield layer, the inner dimension of the shield varies because the braid cannot be flat. Sometimes the braid is silver-plated. For better shield performance, some cables have a double-layer shield; the shield might be just two braids, but it is more common now to have a thin foil shield covered by a wire braid. Some cables may invest in more than two shield layers, such as "quad-shield", which uses four alternating layers of foil and braid. Other shield designs sacrifice flexibility for better performance; those cables cannot be bent as the shield will kink, causing losses in the cable. When a foil shield is used a small wire conductor incorporated into the foil makes soldering the shield termination easier.
For high-power radio-frequency transmission up to about 1 GHz, coaxial cable with a solid copper outer conductor is available in sizes of 0.25
Robert Scott Jenks is an American former professional baseball pitcher. He played in Major League Baseball for the Chicago White Sox and Boston Red Sox from 2005 through 2011. According to the Baseball Almanac, his fastest pitch was clocked at 102 miles per hour on August 27, 2005, at Safeco Field, he threw a slider, a hard, sharp-breaking curveball. Jenks is third all-time in saves by a pitcher in a White Sox uniform. Jenks is a two-time All-Star who held the major league record for retiring consecutive batters. Jenks was not able to play with his teammates at Timberlake High School, in Spirit Lake, Idaho or Inglemoor High School in Kenmore, because of poor grades. Jenks did play his sophomore year of high school for Lakeland High School before Timberlake High School was opened in 1998. Since Jenks was ineligible to play the remaining years of his high school career due to poor academic performance, he played in the Prairie Cardinals American Legion program where he dominated as both a pitcher and hitter.
During his final season for the Prairie Cardinals, Jenks had 123 strikeouts in 92 innings pitched. Jenks was drafted by the Anaheim Angels in the fifth round of the 2000 Major League Baseball Draft. In one minor league game, the radar gun clocked his fastball at 100 mph. During his time with the Angels organization, Jenks spent much of his time on the disabled list because of elbow trouble. Jenks' career with the Angels ended when he was designated for assignment by the team in December 2004. Jenks was claimed off of waivers by the Chicago White Sox for $20,000 and was sent to the club's Double-A affiliate, the Birmingham Barons. Jenks was called up to the major leagues by the White Sox on July 5, 2005; the White Sox made it to the 2005 World Series, Jenks pitched in each of the Series' four games. The White Sox won the series in four straight games over the Houston Astros, Jenks pitched a total of five innings and made the series' final pitch, he recorded saves in Games 1 and 4, had a blown save in Game 2, pitched scoreless 11th and 12th innings in the 14-inning Game 3.
Jenks and Adam Wainwright of the 2006 St. Louis Cardinals are the only rookie closers to earn a save in the clinching game of a World Series. In 2006, Jenks was selected to the American League All-Star team, for the season converted 41 out of 45 save opportunities. Jenks was again selected to the American League All-Star team in 2007. On September 25, 2007, Jenks was named as one of 10 finalist for the "DHL Presents the Major League Baseball Delivery Man of the Year Award". Jenks remains the only White Sox closer to record a save at the All-Star Game, pitching the ninth inning of the 2006 game in Pittsburgh, Pennsylvania. In 2007, Jenks pursued a record streak of retiring consecutive batters. On August 10, 2007, Jenks retired his 38th consecutive hitter, Ichiro Suzuki of the Seattle Mariners, to tie the American League record for most consecutive batters retired in a row, set by David Wells between May 12, 1998, May 23, 1998 with the New York Yankees. On August 12, 2007, in a game against the Seattle Mariners, Jenks retired his 41st consecutive batter, the Mariners' Yuniesky Betancourt, tying the Major League record held by San Francisco Giants pitcher Jim Barr, set over two games on August 23, 1972, August 29, 1972.
On August 20, 2007, Jenks allowed a base hit by Kansas City Royals outfielder Joey Gathright, ending his streak of 41 consecutive batters retired. However, Jenks was still able to get a save during the game. Jenks' record is unique in. Wells' achievement bookended a perfect game that he pitched on May 17, 1998. Barr's achievement was spread across two games, neither of, a no-hitter. In contrast Jenks was perfect for 14 appearances over 27 days, his teammate Mark Buehrle broke the record for most consecutive batters retired on July 28, 2009, ending with 45 in a row. On January 19, 2009, Jenks signed a one-year $5.6 million contract. On December 2, 2010, the White Sox declined to tender him a contract and he became a free agent. After the 2010 season, Jenks signed a two-year, $12 million contract with the Boston Red Sox. Jenks struggled for much of 2011 with injuries, going on the disabled list three times during the season. On September 14, 2011, the Red Sox announced that Jenks had been diagnosed with a pulmonary embolism.
He pitched in 19 games during the season, going 2–2 with an ERA of 6.32. On December 12, 2011, Jenks had this time to remove bone spurs from his back, he was supposed to have only two removed. According to Jenks, Dr. Kirkham Wood, head of the orthopedic bone unit at Massachusetts General Hospital, started to remove a third bone spur and didn't finish it; this created a serrated edge that sliced Jenks' back open in two places, causing him to leak spinal fluid and triggering an infection in his spine. Jenks was forced to undergo emergency surgery on December 28, only two weeks after his first back procedure. Due to his muscles being "torn open," as he put it, Jenks was bedridden for seven weeks; the Red Sox placed Jenks on the 60-day disabled list, ruled him out for at least the first three months of the 2012 season. On July 3, 2012, Jenks was released by the Red Sox, he sued Wood in 2015 for malpractice after learning that Wood was operating on a second patient at the same time as his operation.
Jenks told The Boston Globe that he would have had his bone spur surgery elsewhere had he known about the overlapping schedules. On May 8, 2019, Jenks reached a settlement with MGH and Wood for $5.1 million
The 1975 Copa América Final was the final match to determine the Copa América champion. The first leg was held in Estadio El Campín of Bogotá on October 16, the second leg in Estadio Nacional of Lima on October 22, the playoff match in Estadio Olímpico of Caracas on 28 October; the final was played in a two-legged tie system, the team earning more points would be the champion. A tie on points was resolved in a play-off match to be played at a neutral venue, it happened when Colombia each won a match. Peru would defeat Colombia, 1–0, it was their second title. Hugo Sotil of FC Barcelona scored the goal