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Antennas Systems A system consisting of a transmitting antenna and a receiving antenna. The former is a transmission mode converter for converting a radio wave current or an electromagnetic wave of a traveling wave mode into a spatial electromagnetic wave in a diffusion wave mode, and the latter is a transmission mode converter
The development of the antenna is closely linked to the development of radio technology. Various types of antennas are designed to accommodate the practical requirements that were presented at that time.
The first pair of antennas was designed by the German H.R. Hertz in 1887 to validate the theory of the presence of electromagnetic waves proposed by J.C. Maxwell in the UK. The launch antennas were two balls that were closer to each other, using spark spark between two spheres to produce electromagnetic waves. Receiving antenna with loop antenna. 1901 Italy G. Marconi first use large antenna to achieve ocean communication. Practical first pair of T-type transmission antenna with 50 tapped copper wire, the top connected with the horizontal line, hanging on the two support tower.
The main application of early radio is long-wave ocean communication, antenna research focused on the long wave band. Long wave antenna is characterized by large carrying capacity, large structure, low efficiency.
After 1925, the radio began to prevail, and the omnidirectional wave antenna gradually developed. The earliest mid-wave antenna, is T-shaped, inverted L-shaped and umbrella antenna. In order to overcome the existence of sky-wave interference fading generated over-amplitude distortion, but also designed pull-line and self-propelled tower antenna. The height of this vertical antenna can not only be very high, the energy of the vertically polarized waves can be more concentrated in the direction along the ground to the surrounding radiation, and reduce the high elevation angle of the polarized wave radiation, weakened the decline of the sky Influence, and expand the effective coverage of the ground wave.
1925 years ago, found that the use of ionospheric reflection can be short-wave long-distance communication, and the required power can be greatly reduced, so the directional short-wave antenna has been rapid development. Various types of horizontal antenna and antenna array are designed, including inline horizontal antenna, doubling antenna and wide band traveling wave diamond antenna.
Although in 1927 around Japan Yagi and Yutian proposed wave channel antenna (commonly known as Yagi antenna), until 40 years later, with the oscillation source solution and the development of ultrashort wave communication, Yagi antenna was developed and applied. As early as 1888 H.R. Hertz had proposed a parabolic reflector antenna idea, until 1937 was really put into practical. Horn antenna is in the 20th century, 30 years with the development of waveguide technology. During the Second World War, due to the development of radar technology, microwave antenna corresponding to the rapid development. Parabolic antenna, lens antenna, media bar antenna, slotted antenna and so on in this period have different degrees of progress. Among them, the development of parabolic antenna is particularly prominent, including the design of the irradiator, beam scanning and generate the shape of the map.
Antennas Systems After the end of the Second World War, with the development of microwave relay communication, ultrashort wave mobile radio, television broadcasting and radio astronomy, and the rise of technology such as scattering communication, monopulse radar and synthetic aperture, Antenna, microwave relay periscope antenna, quasi-non-frequency variable logarithmic antenna and isometric helical antenna. In the late 1950s, after the emergence of satellites and intercontinental missiles, the requirements of the antenna, in addition to the high-gain, high-resolution, fast-scan and precise tracking of high-parameter performance, required the antenna due to the urgency of arms competition and the need for electronic warfare Including circular polarization, wide band, multi-function and adapt to the needs of the aircraft conformal embedded and other characteristics. From the 1960s to the early 1970s, the main achievements in the development of the antenna were as follows: (1) the construction and improvement of the antenna of the large earth station, including the application of the jam and the antenna, the feed and the modification of the main and subreflective surfaces, and the beam waveguide; Phased array: due to the improvement of the phase shifter, the application of electronic computer, remote alert rapid response and multi-target simultaneous search and tracking requirements, has been greatly developed; ③ many typical representative of the large radio telescope. In addition, antennas on antennas, such as loading antennas, return antennas, active antennas, and aircraft (including aircraft, rockets, missiles, satellites) have also made significant developments during this period.
Antennas Systems In the 1970s, with the development of radio technology to millimeter-wave, sub-millimeter wave and light wave, frequency reuse, orthogonal polarization, near-field measurement, multi-beam, microstrip antenna, surface wave antenna, coaxial array and reflector antenna And the bitbeat bias and the array antenna signal processing, synthetic aperture and adaptive antenna are also taken seriously and get the corresponding development.
In the 1980s, the development of the antenna in addition to the development of the band to continue to explore the type and performance of the antenna to explore and improve a large number of research work gradually turned to the transmission and reception of transient electromagnetic waves, the target scattering and inverse scattering, The solution of the problem of the problem, the radiation and scattering of the antenna in the special medium
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