Yagi antenna is one of the directional antennas or directional antennas. In contrast to the isotropic antenna, which emits radiation in various directions, up, down, left, right, front and back, with the same strong beam strength. While the Yagi Antenna adds passion in a certain direction, so that the radiation power is only strong in certain directions.
So the Yagi Antenna created by Hidetsugu Yagi is suitable for transmitting and receiving television and radio radiation. Yagi antennas are different from Omni antennas, in which the power of radiation or radiation in all directions remains only at the bottom and is not strong at the top.
In short, the difference between these three antennas is that the isotropic antenna radiates power in all directions so that the radiation pattern is like a ball, while the omni antenna only has power below the bottom so that the radiation pattern is like a donut, while the Yagi antenna radiates in a certain direction so that the radiation pattern is straight.
Thus the Yagi Antenna is a directional antenna because it is directed directly in a certain direction. This antenna like this part that is behind the reflector will have a much smaller gain when we compare it to the front of the antenna which is the director.
Antenna like this does have a risk, namely the beam in other directions outside of the intended direction becomes small. However, such a directional antenna is indispensable when conducting long-distance communication, so there is no need for relay stations in various directions.
In addition, the Yagi Antenna is also very necessary if you want to strengthen the internet modem signal, whether it uses GSM, CDMA, GPRS 3G frequencies or to strengthen the Wireless LAN signal.
Hidetsugu Yagi from the University of Tokyo invented the directional antenna in 1926. There are simple antennas consisting of two elements, some are more complicated. In a directional antenna consisting of two elements, it consists only of a radiator and a guide. The gain strength of this Hidetsugu Yagi antenna can reach 15 dB.
However, the power of this gain will decrease if one part is installed with a reflector. However, more and more elements are installed, requiring calculations that are not simple, especially to determine the spacing and length of each of these directional antenna elements.
If you are going to build this directional antenna yourself, please note that the length of the element is affected by the connections and the diameter of the element itself. Likewise, the number of connections and the diameter of this element will also affect the capacitance.
The formula for calculating the distance between elements and the element length of a Yagi Antenna with two elements is for the driven element 145/f (meters), then spacing 36.6/f (meters) and director 137/f (meters).
Yagi Antenna Parts
To know more about the workings and advantages of this antenna, it's good to know in advance the parts of this antenna. In a Yagi Antenna there are four important parts, namely the driven, director, boom and reflector parts.
These four elements are the basis or the most important part of a directional antenna. The length and distance of these elements will also amplify the transmitting antenna gain as well as determine the exact direction desired.
Driven is a supply point located on the antenna cable. Physically, the length of the driven is half the wavelength of the radio frequency received or transmitted. The second part of this directional antenna is the director section.
The director section is the most important part because this is the part that leads the antenna to a certain point. Physically the size of the director or director is shorter than the driven section. The gain strength of the antenna is also affected by the number of these directions.
But it must be remembered that the more guide rods, the antenna gain will indeed increase or increase but the alignment pattern becomes narrower. Thus, if you want a very precise direction at a certain point with a narrow beam width or not radiating to the left and right too wide, then you can increase the number of director bars.
The next part of the directional antenna is the reflector and boom. The reflector is located at the back of the antenna which functions as a signal reflector. Physically the length of this reflector is 0.55 times the wavelength or longer than the driven length.
The boom itself is the place where the three elements of the directional antenna are placed. Usually the boom is a piece of metal that is physically the same length as the antenna.
How to Arrange a Yagi Antenna
One of the uses of a Yagi Antenna is to strengthen the modem signal, be it GSM, CDMA, Wireless LAN or GPRS 3G. The directional antenna that is prepared is the one that uses an induction system.
A Directional antenna with an induction system is very appropriate for those of you who use a modem or are not equipped with an external antenna connector.
The materials needed to make a directional antenna with this induction system include brass wire with a diameter of 2.5 mm as needed. This brass wire serves as an element for the directional antenna of this induction system.
Brass wire is often used for welding and is available at hardware stores. Then another material needed is a telephone connection box to store the driven and coaxial cable connections.
The next material needed transistor insulator beads. This material is used to prevent electrical and mechanical connections between the element wire and the boom. Then, you also need a 50 ohm coaxial cable which is 15 meters long. You also need a 1 mm cross-section of enamel wire as a material for making a signal induction coil.
Clamps for joining the antenna with the support pole, insulation and hot glue. In addition, you also need G glue and other supporting equipment. When all the materials are available and the supporting equipment has been prepared, you can start working on making a directional antenna to strengthen your internet modem signal.
Try to do it you take into account in accordance with the provisions so that the results can really strengthen the signal as you want. The accuracy of calculating and cutting the length of each element and storing it at a predetermined distance, is the secret to the success of making this antenna.
How to make it is to cut aluminum tubing measuring 0.5 inches along 99 cm as a driven. Mark this aluminum part with a marker at the center distance. Then cut 3/8 inch aluminum as the reflector material. Also cut 1 inch aluminum as the antenna boom material.
If you want to make an 8 element amplifier antenna, the boom length is 2.65 meters. But you have to give tolerance on the left and right sides of 5 cm, so that what must be cut is 275 cm. The next step is to install all the reflector and director elements in place.
Meanwhile, to create a driven element, you must first create a gamma match. When the gamma match has been completed, all you have to do is insert the boom and elements in their respective places in the order.
You attach the antenna reflector to the boom which is 5 cm from the boom end, then place the last director part on the boom end which is 5 cm from the boom front end.
It should be noted that between the director and the last reflector are in the same plane, tighten all bolts when you are sure there are no misaligned parts.
The final step is to re-check and ensure that the director, driven and reflector elements are on a level plane. Good luck!