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SUMMARY / RELATED TOPICS

Radiation pattern

In the field of antenna design the term radiation pattern refers to the directional dependence of the strength of the radio waves from the antenna or other source. In the fields of fiber optics and integrated optics, the term radiation pattern may be used as a synonym for the near-field pattern or Fresnel pattern; this refers to the positional dependence of the electromagnetic field in the near-field, or Fresnel region of the source. The near-field pattern is most defined over a plane placed in front of the source, or over a cylindrical or spherical surface enclosing it; the far-field pattern of an antenna may be determined experimentally at an antenna range, or alternatively, the near-field pattern may be found using a near-field scanner, the radiation pattern deduced from it by computation. The far-field radiation pattern can be calculated from the antenna shape by computer programs such as NEC. Other software, like HFSS can compute the near field; the far field radiation pattern may be represented graphically as a plot of one of a number of related variables, including.

Only the relative amplitude is plotted, normalized either to the amplitude on the antenna boresight, or to the total radiated power. The plotted quantity may be shown on a linear scale, or in dB; the plot is represented as a three-dimensional graph, or as separate graphs in the vertical plane and horizontal plane. This is known as a polar diagram, it is a fundamental property of antennas that the receiving pattern of an antenna when used for receiving is identical to the far-field radiation pattern of the antenna when used for transmitting. This is proved below. Therefore, in discussions of radiation patterns the antenna can be viewed as either transmitting or receiving, whichever is more convenient. Note however that this applies only to the passive antenna elements. Active antennas that include amplifiers or other components are no longer reciprocal devices. Since electromagnetic radiation is dipole radiation, it is not possible to build an antenna that radiates coherently in all directions, although such a hypothetical isotropic antenna is used as a reference to calculate antenna gain.

The simplest antennas and dipole antennas, consist of one or two straight metal rods along a common axis. These axially symmetric antennas have radiation patterns with a similar symmetry, called omnidirectional patterns; this illustrates the general principle that if the shape of an antenna is symmetrical, its radiation pattern will have the same symmetry. In most antennas, the radiation from the different parts of the antenna interferes at some angles; this results in zero radiation at certain angles where the radio waves from the different parts arrive out of phase, local maxima of radiation at other angles where the radio waves arrive in phase. Therefore, the radiation plot of most antennas shows a pattern of maxima called "lobes" at various angles, separated by "nulls" at which the radiation goes to zero; the larger the antenna is compared to a wavelength, the more lobes there will be. In a directive antenna in which the objective is to direct the radio waves in one particular direction, the lobe in that direction is larger than the others.

The axis of maximum radiation, passing through the center of the main lobe, is called the "beam axis" or boresight axis". In some antennas, such as split-beam antennas, there may exist more than one major lobe. A minor lobe is any lobe except a major lobe; the other lobes, representing unwanted radiation in other directions, are called "side lobes". The side lobe in the opposite direction from the main lobe is called the "back lobe". Minor lobes represent radiation in undesired directions, so in directional antennas a design goal is to reduce the minor lobes. Side lobes are the largest of the minor lobes; the level of minor lobes is expressed as a ratio of the power density in the lobe in question to that of the major lobe. This ratio is termed the side lobe ratio or side lobe level. Side lobe levels of −20 dB or greater are not desirable in many applications. Attainment of a side lobe level smaller than −30 dB requires careful design and construction. In most radar systems, for example, low side lobe ratios are important to minimize false target indications through the side lobes.

For a complete proof, see the reciprocity article. Here, we present a common simple proof limited to the approximation of two antennas separated by a large distance compared to the size of the antenna, in a homogeneous medium; the first antenna is the test antenna. The second antenna is a reference antenna; each antenna is alternately connected to a transmitter having a particular source impedance, a receiver having the same input impedance. It is assumed that the two antennas are sufficiently far apart that the properties of the transmitting antenna are not affected by the load placed upon it by the receiving antenna; the amount of power transferred from the transmitter to the receiver c

Stela of Shamshi-Adad V

The Stela of Shamshi-Adad V is a large Assyrian monolith erected during the reign of Shamshi-Adad V. The stela was discovered in the mid nineteenth century at the ancient site of Kalhu by the British archaeologist Hormuzd Rassam. Dated to between 824-811 BC, the sculpture is now part of the British Museum's collection of Middle East antiquties; this stela was found by Rassam in 1855 near the Temple of Nabu at Nimrud. It was shipped to London the following year to become part of the British Museum's Assyrian collection, where it is displayed alongside the Kurkh Monoliths and adjacent to the Black Obelisk of Shalmaneser III and the White Obelisk of Ashurnasirpal I; the stela portrays the Assyrian King worshipping five gods in a format similar to the Stela of Ashurnasirpal II. The monarch is shown wearing a conical hat and full beard in archaic style, with his right hand extended snapping his fingers, his left hand holding a mace, symbol of royal authority; the five deities are represented symbolically in the top left hand corner of the stela: Ashur by a horned helmet, Shamash by a winged disk, Sin by a crescent, Adad by a forked line and Ishtar in the form of a star.

A large amount of cuneiform text written in an earlier, obsolete style covers the sides of the stela, recording the king's military campaigns. J. E. Reade, Assyrian Sculpture A. K. Grayson, Assyrian Royal Inscriptions J. E. Curtis and J. E. Reade and empire: treasures from A. H. Layard, Discoveries in the ruins of Nineveh and Babylon

Wieden

Wieden is the 4th municipal District of Vienna, Austria. It is near the centre of Vienna and was established as a district in 1850, but its borders were changed later. Wieden is a small region near the city centre. After World War II, Wieden was part of the Soviet sector of Vienna for 10 years; the name Wieden was first recorded in 1137, is thus the oldest Vorstadt of Vienna. The main street is even older; the district was the site of the former royal Summer residence, completed under Ferdinand II, was expanded many times until Maria Theresa sold it to the Jesuits. Today it is the Theresianum, a prestigious private boarding school, while the Diplomatic Academy of Vienna resides in a wing of the building. In the beginning of the 18th century, the development of Wieden as a suburb began. Many palaces and other buildings were built. Two small Vorstädte in the area of the present fourth district were Hungelbrunn and Schamburgergrund; these three areas along with a number of others were incorporated into the city of Vienna as the fourth district on March 6, 1850.

Because of social and economic differences, Margareten was separated from the fourth district to form the fifth district in 1861. The so-called Freihaus, built in 1700 and the largest apartment building/tenement of the time, was located in this area, although by 1970 its state had deteriorated; the name has been rehabilitated in recent years to give an identity to the local bars and independent retailers. During the occupation by the allies, Wieden was part of the Soviet sector of Vienna; the Vienna University of Technology is located in this district with its main administration buildings being located in Karlsplatz and a nearby satellite campus in the 6th district across the Wienzeile. Johannes Brahms, German composer, lived here Christoph Willibald Gluck, lived here Ferdinand Bloch-Bauer, sugar manufacturer and art lover, lived here Karl Kraus, an Austrian writer and journalist, one of the foremost German-language satirists of the 20th century, lived here Rosa Mayreder, an Austrian freethinker, painter and feminist Emanuel Schikaneder, a German impresario Johann Strauss II.

Composer of light music dance music and operettas, lived here Nicholas Treadwell, art collector and performer Cäcilia Cordula Weber, née Stamm, the mother of Constanze Weber, wife of Wolfgang Amadeus Mozart, died here Josephine Haas, a female German-Austrian philanthropist and died here Joseph Ulrich Danhauser, Austrian furniture maker, father of Josef Danhauser Josef Feid, Austrian painter, born here Adalbert Nikolaus Fuchs, Austrian agricultural scientist, born here Karl Lueger, Viennese mayor, born here Johann Matthias Ranftl, Austrian artist, born here Johann Heinrich Steudel, born here Freihaus Karlskirche: a famous and special baroque church Naschmarkt: the famous and the largest market of Vienna Karlsplatz Stadtbahn Station: Art Nouveau building constructed by Otto Wagner Theresianum Vienna Museum: museum covering Vienna's history ORF building The headquarters of the national broadcaster's radio stations. "Wien - 5. Bezirk/Wieden", Wien.gv.at, 2008, webpage: Wien.gv.at-wieden

Ancestral shrine

An ancestral shrine, hall or temple called lineage temple, is a Chinese temple dedicated to deified ancestors and progenitors of surname lineages or families in the Chinese traditional religion. Ancestral temples are linked to Confucian culture and the emphasis that it places on filial piety. A common central feature of the ancestral temples are the ancestral tablets that embody the ancestral spirits; the ancestral tablets are arranged by seniority of the ancestors. Altars and other ritual objects such as incense burners are common fixtures. Ancestors and gods can be represented by statues; the temples are used for collective rituals and festivals in honor of the ancestors but for other family- and community-related functions such as weddings and funerals. Sometimes, they serve wider community functions such as local elections. In traditional weddings, the ancestral temple serves a major symbolic function, completing the transfer of a woman to her husband's family. During the wedding rites, the bride and groom worship at the groom's ancestral shrine, bowing as follows: first bow - Heaven and Earth second bow - ancestors third bow - parents fourth bow - spouseThree months after the marriage, the wife undertakes worship at the husband's ancestral shrine, in a rite known as miaojian.

Ancestral temples have been secularized to serve as village schools or granaries during the land reform of the 1950s and the Cultural Revolution. They have experienced a revival since the economic liberalization of the 1980s; the revival of the ancestral temples has been strong in southern China where lineage organization had stronger roots in the local culture and local communities are more to have members living overseas who can support rebuilding of the shrines through donations. Notable ancestral temples in Hong Kong include: Tang Ancestral Hall and Yu Kiu Ancestral Hall, along the Ping Shan Heritage Trail King Law Ka Shuk Tang Chung Ling Ancestral Hall Ancestral shrines or similar concepts are common in other religions and cultures. Other East and Southeast Asian but traditional African religions have ancestral shrines and or tombs. Ancestor worship is an important and common element in native African religions and is still common and practiced by followers of folk religions but Christian and Muslim Africans.

Chinese folk religion—Confucianism Chinese lineage associations Ancestral home Chinese kin Zupu Guanxi Kongsi China Ancestral Temples Network Ancestral halls in Tai Po, Hong Kong

2013–14 2. Liga (Slovakia)

The 2013–14 season of the 2. Liga was the 21st season of the second-tier football league in Slovakia, since its establishment in 1993. Twelve teams competed in the league, with bottom side will play the relegation play-offs. DAC Dunajská Streda was promoted to the Slovak First Football League after the 2012–13 season. 1. FC Tatran Prešov was relegated from the Slovak First Football League after the 2012–13 season. Spartak Trnava juniori and FK Pohronie were promoted from the Slovak Third Football League after the 2012–13 season. MFK Dolný Kubín and Ružiná were relegated to the Slovak Third Football League after the 2012–13 season. MFK Tatran Liptovský Mikuláš, who finished 12th, faced ŠK Futura Humenné, the 10th-placed 2013–14 3. Liga side for a one-legged play-off. Updated through matches played 31 May 2014. 2013–14 Slovak First Football League 2013–14 3. Liga List of transfers summer 2013 League table, recent results and upcoming fixtures at Soccerway

Earle School District

Earle School District is a public school district based in Earle, United States. The school district encompasses 135.16 square miles of land, including portions of Crittenden County and Cross County serving Earle and most of Jennette. Founded in 1919, the district proves comprehensive education for more than 700 pre-kindergarten through grade 12 students while employing more than 140 teachers and staff; the district and its schools are accredited by the Arkansas Department of Education. In 2017 the district had 560 students. In November 2017 the district was placed under the control of the Arkansas Department of Education. Earle High School, located in Earle and serving more than 325 students in grades 7 through 12. Earle Elementary School, located in Earle and serving more than 375 students in pre-kindergarten through grade 6. Official website