Directional antenna . The antennas directional unlike antennas omnidirectional an antenna directional (also called unidirectional or directive) is an antenna capable of concentrating most of the energy radiated so located, thus increasing the power transmitted to the receiver or from the source desired and avoiding interference introduced by unwanted sources.
The directional antennas , such as antennas Parabolic , provide much better performance than the dipole antennas when it is desired to concentrate a large part of the radiation in a desired direction, with a gain of 29 dBi can be mounted for horizontal or vertical polarization. Perfectly designed to operate under the most severe environmental conditions. Its high quality construction allows easy adjustment both in azimuth and elevation, recommended for use in Client or Point-to-Point equipment .
Summary
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- 1 Introduction
- 2 Directional antenna for 144 MHz
- 3 Holding plate
- 4 Image Gallery
- 5 See also
- 6 Sources
Introduction
The Yagi antenna is a directional antenna invented by Dr. Hidetsugu Yagi of Tohoku Imperial University and his assistant, Dr. Shintaro Uda (hence the name Yagi-Uda). This invention, advanced to conventional antennas , produced that by means of a simple dipole structure , combined with parasitic elements, known as reflectors and directors, it managed to build a very high performance antenna .
Use of a Yagi antenna in radio orientation . Dr. Yagi’s invention (patented in 1926) was not originally used in Japan, since the design of the antenna was not to be implemented in communications but to be used in war as a radioactive weapon.
Yagi experimented with mice that he subjected to strong radio waves that were concentrated thanks to the directionality of the antenna . The results were not good for Yagi and he abandoned the project. However, it was accepted in Europe and North America , where it was incorporated into commercial production, broadcast systems, TV and others. Using this antenna in Japan only began to be used during the World War II , when it was discovered that the invention of Yagi , was used as an antenna of radar by armies allies.
Directional antenna for 144 MHz
| Directional antenna |
| Yagi Directional Antenna : Elements A, B and C are the directors, all three are the same and are 92cm long. Element D is the active element, its total length (from end to end) is 94 cm. Element E is the reflector, it has a length of 110 cm. This antenna is of the Yagui type with vertical or horizontal radiation . For the construction of the elements, an aluminum rod of 0.5 cm section can be used (we can get it from the remains of some old TV antenna); For the boon, a 2 X 2 cm aluminum tube will be used. section and 135 long. |
Clamping plate
| The clamping plate of the two arms |
| The plate that supports the two arms of the active element must be made of insulating material (vaquelite, methacrylate, PVC, etc.). The drop line will connect the pipe to the upper arm and the mesh to the lower arm. With a copper wire of 2.5 mm section the two arms will be connected, ensuring that it is isolated from the boon; measurements can be modified to adjust stationary |
Image gallery
| Directional antennas ( Wifi antennas ) | |
| Directional Antenna: Yagi type antenna: they are similar to television antennas | Planares or Panels: These although they do not have as much scope, but it is much easier to orient them and they are not so bulky, so their installation is very simple. |
| Omnidirectional Antennas ( Wifi Antennas )
· The Omnidirectional antennas “send” the information theoretically to 360 degrees so it is possible to establish communication regardless of the point where you are, since they do not require orientation. In contrast, the range of these antennas is less than that of the directional antennas. |
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| Omnidirectional antennas | Omnidirectional antennas | Omnidirectional antennas | Omnidirectional antennas |
| Sector Antennas ( Wifi Antennas )
· Sector Antennas: They are the mixture of directional and omnidirectional antennas. The antennas sectoral emit a broader beam directional but not as broad as omnidirectional . Similarly, its range is greater than an omnidirectional and less than a directional. To have a 360º coverage (like an omnidirectional antenna ) and a long range (like a directional antenna) we will have to install three 120º sector antennas or 4 80º sector antennas. This 360º system with sectors is called ” Array “. Sector antennas are typically more expensive than directional or omnidirectional antennas. |
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| Sector antennas | Sector antennas | Sector antennas |
