Antennas are an indispensable part of wireless transmission. In addition to our use of optical fibers, cables, network cables, etc. to transmit wired signals, as long as it is a signal that uses electromagnetic waves to propagate in the air, various forms of antennas are needed. Today we come to understand the antenna according to the shape to understand the classification!
Duck rubber/Whip antenna
Generally, the work is not high. In the U/V band, there are many deformed forms, such as rod antennas, spring antennas, etc., an omnidirectional antenna often used in automobiles, wireless WIFI, and walkie-talkies. The gain is not high, generally within 10dBi. A higher performance index can be achieved through multiple arrays (PHS rod antennas).
Mobile communication base stations use the most antennas. The advantages of this antenna are: high gain, good sector pattern, small backlobe, convenient vertical pattern depression angle control, reliable sealing performance and long service life.
Generally used in indoor wireless coverage scenarios. According to their different radiation forms, they can be divided into directional ceiling antennas and omnidirectional ceiling antennas. Omni-directional ceiling antennas can be divided into single-polarized ceiling and dual-polarized ceiling. kind.
Yagi antenna / log periodic antenna
Yagi antennas are mainly used for link transmission and repeaters, and have the advantages of high gain, light structure, convenient installation, and low price. The greater the number of antenna elements, the higher the gain. Generally, Yagi directional antennas with 6-12 elements are used, and the gain can reach 10-15dBi. The old TV receiving antenna used a Yagi antenna. Log-periodic antennas are similar to Yagi antennas. By adjusting the frequency of each radiating unit, it has a wide-band coverage capability and is mainly used for link relay and radio direction finding.
A highly directional antenna specially used for long-distance communication has an extremely narrow beam width and a high gain value. It can also be called a high-gain directional antenna. There are also various variants, including feed-forward paraboloids, rear-fed Cassegrain antennas, and grid antennas for weight reduction and low frequency use. This kind of antenna is usually used for point-to-point communication. The antennas must be precisely aimed at each other, and there must be no obstructions between the antennas (Light of Sight).
The parabolic antennas we have seen are large and small. The small ones are like household “pot lids”, and the larger ones are like the “big pot lids” of satellite receiving stations with a diameter of more than ten meters. This size is called the caliber. The larger the caliber, the antenna The higher the gain.
PCB antenna: PCB antenna is the most common planar antenna, which can be small pieces or small loops, spiral or linear. Their BOM cost is negligible, they only take up PCB space, are low in cost, do not need to assemble the antenna separately, are not easy to touch and damage, and the whole machine is easy to assemble, but at a cost — sacrificing performance.
Dielectric ceramic antenna: Because the size of the antenna is related to the working wavelength, one of the disadvantages of PCB antennas is that if better performance is required, the size will increase. Dielectric ceramic antennas can better solve this problem. The dielectric constant is very high and it takes up a small space. Typical applications are GPS and Bluetooth antennas.
Conformal antennas: Planar antennas have another significant advantage: if a flexible printed board is used, the antenna can be closely attached to the surface of the object, and even the antenna can be fabricated on the surface of the object, resulting in conformal antennas, aircraft, missiles, etc. Both surfaces can be used; combined with laser engraving technology, conformal antennas (FPC antennas, LDS antennas) can be made on the phone shell.
The horn antenna is a kind of microwave antenna, which belongs to the surface antenna. The circular or rectangular cross-section microwave antenna with gradually expanded wave guide terminal has the advantages of simple structure, wide frequency bandwidth, large power capacity, and convenient adjustment and use. If the horn size is selected reasonably, good radiation characteristics can be obtained.
There are many sub-categories of horn antennas, including standard gain horns, cone horns, pyramid horns, double ridge horns, lens horns, corrugated horns, and so on.