British radar antennas that have repeatedly made great achievements in World War II
Everyone must be familiar with the English name of the antenna is generally called Antenna; in fact, its other name is Aerials. The so-called Aerials is a long wire used to transmit or receive radio signals. As can be seen from this name, the experimenters looked like the antenna before they even carried the antenna.
Let's try to understand the antenna in the way of " History as A Mirror". The most important thing is to see the interesting experiment and brainstorming spirit of the antenna. Finally, we should briefly introduce the development history of the antenna...
First, an interesting history of antenna invention
「Whitfield Whire」 discovered the beauty of the wire
We returned to the earliest radio era. Before the power was invented, all machines were supplied with kerosene, such as the kerosene-powered refrigerator.
In the early days, there was an experimenter named "Whitfield Whire". The radio transmitter he invented could make a big spark, but the signal could not be transmitted. In fact, the transmitter he invented was the radio generated by the principle of spark discharge. But what made him most embarrassed was that he tried a myriad of methods, that is, he could not receive the signal transmitted by this transmitter. It was received later, but the signal was weak.
In order to further verify whether the wave can pass through the table, he placed the transmitter under the table. In order to obtain the signal, the receiver was suspended from the ceiling above the table. What surprised him was that the wire of the receiver was hung. It made the receiver much more efficient. Therefore, he left the hanging wire there. From then on, he called his receiver a "radio receiver" (WIRELESS SET), and he took this one. The results were compiled into a report published in the US QST magazine (the world's first amateur radio magazine).
「Garfield Grownd」 Discover the benefits of grounding
After several years, an experimenter named Garfield Grownd found that the table lamp on the table had two wires, but the receiver had only one antenna. Why only one antenna can behave. So good, so he will discuss the issue of this issue.
This problem naturally plagued him, but it was such a coincidence that after he bought a car, he found that the lights were also using a wire, and of course, the other line was the outer casing of the car. This made him think of a question: Would it be better to connect one of the transmitter's wires to a common contact? So he used a metal tube to break into the ground and pulled a line to the top of the transmitter, which made the signal much more powerful. Similarly, he published this important discovery in QST magazine. In this article, he suggested that every amateur radio station needs to have "GROWND".
「Diogenes Dipole」Invented double dipole antenna
The next major breakthrough in the antenna was invented by Diogenes Dipole.
One day, when Depp (Dai Bo's nickname) walked through a playground, he found that the local lion members were playing the seesaw. He found that these lion members were quickly able to maintain balance, presumably, some of them had the capacity to make the seesaw Maintain balance in a short period of time.
When Depp returned home, he immediately took a wire and connected it to the machine casing, and the other wire was connected to the transmitter output, which became a new set of antennas. In fact, this antenna is also known as the "double dipole" (DIPOLE) antenna, which is named after his name in memory of Dai Bai.
Count Herpoise」Inventing the virtual ground of the antenna
After reading the Whire Grownded Balanced-Lion-fed Dipole antenna monograph in QST magazine, a European nobleman named Count Herpoise found that his desk lamp was not just two lines, but three lines. The country's power system uses 330V, which is natural, but he thinks why there are three lines in North America using 220V power. This also led him to invent the "virtual ground line", which is rarely known in theory, and some people even disagree with this theory. However, those who are interested in antennas today must know that virtual grounding is necessary, and these "virtual grounding" is usually called COUNTERPOISE, which is commemorated by the name of the inventor.
「Von Trap」The first one to create a shorter double dipole antenna
I also read the Von Trap of the Whire Grownded Balanced-Lion-fed Dipole antenna monograph on QST. Because his space is not big enough to set up a double dipole antenna, he walks along the antenna every few times. Around the mile, a few turns, the long part is wound up, and the capacitor is connected in parallel with the wound inductor. This is the birth of "TRAP DlPOLE".
「Morries Nimatch」Put forward antenna theory, invention standing wave ratio table
Since the release of QST magazine in the United States, the most legendary about the history of antennas is "Morries Nimatch," whose friends all call him Mo. It is the first to propose an antenna theory to explore the physicist about how much power is fed to the long antenna and how much will not be radiated. In order to thoroughly understand this theory, he wanted to know how much power was emitted and how much it was reflected back. So he invented the "stationary wave ratio table" (the current English name of the standing wave ratio SWR is called Standing Wave Ratio. Abbreviation for See What Returns, meaning how much power is being turned back.)
In order to commemorate this inventor of the standing wave ratio table, some people have previously called the standing wave ratio table as MoNimatch. So far, the production of the standing wave ratio table is still based on this.
OST magazine reported that it was extremely successful Monimatched Whire Grownded Count Herpoise Balanced-Lion-fed Trap Dipole Antenna。From the above ranks, it has developed like a Hindu mentor.
「Raoul Random」Found antenna matching
Later, Raoul Random found that the objects on both sides of the slab were different, but the adjustment distance could be balanced. The antenna should also be manually adjusted to achieve balance (match).
「Hertz」 Establishes the first antenna system
In 1865, the German physicist Hertz (1857-1894, 37 years old) established the first antenna system. The assembly equipment of the time can now be described as a complete radio system operating at the wavelength of the meter wave, which uses a terminal-loaded dipole. The sub-transmission antenna uses a resonant square ring as the receiving system.
Hertz antenna system
「Marconi」 Pioneered commercial radio and transoceanic communications
In December 1901, Italian Bologna researcher Marconi added a tuned circuit to Hertz's system, equipped with a large antenna and grounding system for longer wavelengths, and received a message from Bordeaux, England, in St. John's, Newfoundland. 2.5km radio report. Commercial radio was developed and transoceanic communication was created.
In these initial studies, antennas have gained widespread attention and application, and their development can be roughly divided into three historical stages.
Sencond,Antenna development history
1.Line antenna period (late 19th century to early 1930s)
In 1901, Marconi's trans-Atlantic exchange in Newfoundland, Canada, was launched by the British “Consulphate Peninsula” letter, which opened up a new era of radio long-distance communication. The transmitting antenna used at that time was a fan-shaped structure formed by obliquely pulling 50 copper wires from a 48 m high traverse line. It can be considered as the first practical monopole antenna, and the oscillating source is a 70 Hz spark generator. Subsequently, a four-story wooden tower was used to erect a wire mesh to form a square single-cone antenna, as shown in the figure, with an emission wavelength of 1000 m.
Single cone antenna
With the invention and development of electron tubes in the early 20th century, this period began with long-wave communication, and then developed into China-wave communication. Due to the discovery of the ionosphere, short-wave communication and long-distance broadcasting began around 1924. This period also established the basic theory of wire antennas.
2.Antenna period (early 1930s to late 50s)
On the eve of World War II, the invention of microwave klystrons and magnetrons led to the emergence of microwave radars, and the centimeter wave became popular, and the radio spectrum was more fully utilized. Parabolic antennas or other forms of reflector antennas have been widely used during this period. These antennas are planar antennas or antennas. In addition, waveguide slot antennas, dielectric rod antennas, helical antennas, and the like have appeared. Applications such as microwave relay communication, broadcasting and radio astronomy have further developed and improved the area antenna and line antenna technology. During this period, the aperture antenna and basic theory, such as geometric optics and aperture field method, were established. The antenna test technology was invented and the integrated technology of the antenna array was developed.
3.Great development period (from the 1950s to the present)
In 1957, the man-made earth satellite marked the beginning of a new era of human development, and also put forward many high requirements on the antenna, such as high gain, precision tracking, fast scanning, wide frequency band, low side lobes and so on. At the same time, advances in electronic computers, microelectronics and modern materials have provided the necessary foundation for the development of antenna theory and technology. In 1957, the United States made a single-pulse antenna for precision tracking radar AN/FPS-16, up to 0.1 mil. In 1963, a high-efficiency dual-mode horn feed was introduced. In 1966, a corrugated horn was invented. In 1968, a high-power phased array radar AN/FPS-85 was fabricated. In 1972, the first practical microstrip antennas were fabricated. And as a conformal antenna for rockets and missiles, applications have begun.
In recent years, there have also been forms of miniaturized antennas such as fractal antennas. Another important development has been the development of antenna signal processing capabilities. The theoretical progress is: the establishment of the moment method (MOM), the finite difference time domain method (FDTD) and Analytical methods such as Geometric Diffraction Theory (GTD) have been developed into commercial software. In the aspect of antenna measurement technology, microwave darkroom and near-field measurement technology were developed, and the test technology of tightening antenna test field and using radio source was developed, and an automated test system was established.
Phased slot array antenna of AN/APG-68 fire control radar on American F-16 fighter plane
Spiral antenna array on GPS
Third, Future prospects
Today, antennas are widely used in mobile communications, radar, navigation, satellite, meteorology, car networking, Internet of Things era, remote interactive teaching, remote ultrasound, UAV remote sensing, wireless virtual projection and other fields. Antenna technology has many of the characteristics of a mature science and remains a dynamic technology field. The main development directions are: multi-functional (more than one generation), intelligent (providing information processing capabilities), miniaturization, integration and high performance (wideband, high gain, low sidelobe, low cross polarization, etc.) .
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