UHF antenna with their own hands. Homemade UHF antenna for digital television
In times of huge tube televisions, a good antenna was in short supply for good reception. Those that could be bought in stores were not of high quality. Therefore, people made television antennas with their own hands. Today, many are interested in homemade devices. And even when very often digital technologies, this interest does not fade.
This era has touched television. Today, T2 broadcasting is developing most widely. It has its own characteristics. In those places where the signal level slightly exceeds the interference, a sufficiently high-quality reception is obtained. There is simply no further signal. There is nothing to interfere with a digital signal, however, in a situation of cable mismatch or various phase distortions, almost anywhere in the transmitting or receiving path, the picture can be square, even with a strong signal level.
There are other changes in modern television.So, all broadcasting is in the UHF range, the transmitters have good coverage. The conditions under which radio waves propagate through cities have changed greatly.
Before you start manufacturing, you need to define some parameters of these structures. They, of course, require in-depth knowledge in various areas of mathematics, as well as the laws of electrodynamics.
So, the gain is the ratio of the power at the input of the reference system to the force at the input of the antenna used. All this will work if each of the antennas creates values of intensity and density of the flow with the same parameters. The value of this coefficient is dimensionless.
The directional coefficient is the ratio of the field strength, which the antenna creates, to the field strength in any direction.
It is necessary to remember that such parameters as KU and KND are not interrelated. There is a UHF antenna for digital TV, which has a very high directivity. However, its gain is small. These designs are directed into the distance. There are also designs with high directivity. Here it comes in combination with a very powerful gain level.
Today you can not look for formulas, but use special programs. They already take into account all the necessary parameters. You just have to enter some conditions - and you get a complete calculation of the UHF antenna, then to collect it.
Any structural element in which the signal currents flow must be connected using a soldering iron or welding machine. A similar knot, if it is outdoors, suffers from contact disturbance. From this, the various parameters of the antennas and the reception level can become much worse.
This is especially true for points with zero potentials. According to experts, they can observe the voltage, as well as the antinode of the current. To be precise, this is the maximum current value. Is it present at zero voltages? This is not surprising.
Such places are best made from solid metal. Creeping currents are unlikely to affect the picture if the connections are made by welding. However, due to their presence, the signal may disappear.
How and what to solder?
Antenna DMV do it yourself is not very easy to make. This involves working with a soldering iron.Modern manufacturers of television cable no longer make it copper. Now there is an inexpensive alloy, resistant to corrosion. These materials are hard to solder. And if they are heated long enough, there is a risk of burning the cable.
Experts recommend using low-power soldering irons, low-melting solders, and fluxes. Do not feel sorry for pasta when soldering. Solder will fall correctly only if it is under a layer of boiling flux.
In order to enjoy digital television, it is enough to purchase a special tuner. But it does not have a built-in antenna. And those that are offered as special digital, too expensive and meaningless.
Now we will learn to catch the T2 on a completely self-made design. Homemade antenna DMV - it's easy, cheap, high quality. Try it yourself.
The simplest antenna
To build this design, you will not even need to go to the store. For the manufacture of its rather ordinary antenna cable. You need 530 mm of wire for the ring and 175 mm of which will be made loop.
The TV antenna itself is a ring of cable. Clean the ends and then connect them to the loop.And to the latter, you need to solder the cable that connects to the T2 tuner. So, on the ring, the screen and the central core are connected to the loop screens. At the last central cores are also connected. And the cable to the tuner is soldered standard to the screen and the central core.
That turned out antenna DMV, made by hand. Its design was very cheap and practical. And it works no worse than expensive store options. It needs to be fixed on plywood or plexiglass. For this perfect construction clamps.
This design is a disc made of aluminum. The outer diameter of the element should be 365 mm, and the inner diameter - 170 mm. The disc must be 1 mm thick. First you need to make a cut in the disc (10 mm wide). In the place where it is cut, you should install a PCB from PCB. It should be 1 mm thick.
The board must have holes for screws MZ. The board must be glued to the disk. Then you need to solder the cable leads to it. The core should be soldered to one side of the disk, the screen to the other. As for quality, such a TV antenna will receive better with two discs, especially if it is far away from the television transponder.
For the manufacture of this design will not be used anything supernatural. We will do it from various scrap materials. However, although it is home-made, it will work fine in the entire decimeter range. So, this antenna DMV, with their own hands quickly manufactured, is not inferior to the store, more expensive designs. For the reception of T2 it will be enough.
So, to assemble this design, you need empty cans of canned food or beer. You need 2 cans with a diameter of 7.5 cm. The length of each is 9.5 cm. You also need to stock up on stripes of textolite or getinaks, always with foil.
Our banks need to be connected to the PCB with a soldering iron. The plate of this material, which will connect the containers at the top, must have a solid coating of copper foil. On the bottom plate, the foil should be cut. This is done for easy cable connection.
It is necessary to assemble the structure in such a way that the total length is not less than 25 cm. This antenna (UHF-band) is a broadband symmetrical vibrator. Due to its surface area, it has large gains.
If suddenly you can not find suitable banks, then you can use containers with a smaller diameter. However, then the foil will have to be cut on the upper connecting plate.
Do you like to drink beer? Do not throw away jars. From them you can make a good antenna. To do this, you need to fix two beer cans on any dielectric material.
First you need to choose the appropriate cable, and then bring it to mind. For this cable must be cleaned. You will see shielding foil. Under it will be a protective layer. But under it you can directly observe the cable.
For our antenna, you need to strip the top layer of this wire by about 10 cm. The foil must be gently screwed in order to eventually branch out. The protective layer for the central core should be stripped 1 cm.
On the other hand on the cable you need to solder the plug for the TV. If you were a subscriber of cable networks, then this part and cable will not even have to be purchased separately.
Now for the cans. It is advisable to use beer containers with a volume of 1 l. However, good German beer in such banks is expensive, and domestic is not sold.
Banks need to be uncorked very carefully. Then you need to free the container from the contents, and then dry well. Further follows by means of the self-tapping screw to connect our screen on a cable and bank. To the second you need to fasten the central core.
For a higher quality image, it is better to connect the capacitance and the cable with a boot.
It is necessary to fasten the banks on any dielectric material. It should be noted that they should be located in one straight line. The distance between them depends on the capacity. All this is selected only by experience.
The zigzag antenna UHF has the simplest design. The item itself is broadband. Its device allows you to allow various deviations from the original design parameters. At the same time its electrical parameters are almost not violated.
Its input resistance in a certain range depends on what sizes will be the conductors that will form the basis of the canvas. There is a dependency. The greater the width or thickness of the conductors, the better the antenna will be matched to the feeder. In general, for the manufacture of cloth, you can use any conductors.For this fit and plates, and tubes, and corners, and much more.
In order to increase the directivity of such an antenna, it is permissible to use a flat screen that will play the role of a reflector. The latter will reflect in the direction of the antenna high-frequency energy. Such screens often have serious dimensions, and the phase depends mainly on the distance.
On the practical side, the reflector is only rarely made from a single sheet of metal. More often it is made in the form of conductors, which are connected in the same plane. For constructive reasons, do not make the screen too tight. The conductors from which the screen itself will be made are joined by welding or soldering to the metal frame.
This construction is made very simply. It works well in the UHF range. In the USSR, it was a real popular irreplaceable model. It has a small size, so it can be used as a UHF indoor antenna.
The material will be copper tubes or aluminum sheet. The side parts can be made of solid metal. Often they are tightened with a net or covered with a tin. If one of the indicated methods is used, in this case the structure should be soldered along the contour.
The cable can not bend sharply.How to carry out this element, you can see on the pictures.
It must be conducted in such a way that it reaches the lateral angle, but does not extend beyond the antenna or the lateral square.
MW UHF indoor antenna
This design is designed for easy and confident reception of digital television signals. It can be made easily and very quickly. To do this, you need an aluminum or copper bar. Its length should be up to 1800 mm. This antenna can also be used as an outdoor one.
The design is a frame in the form of a diamond. There should be two. One plays the role of a vibrator, the second works as a reflector. For the reception of T2, it is necessary that the side of our diamond is approximately 140 mm, and the distance between them is 100 mm.
After the frame is made, and the design will gain rigidity, a dielectric is mounted between the two ends of our bar. It could be anything. The shape and size are completely irrelevant. The distance between two points of the bars should be approximately 20 mm. The tops of our lozenges need to be joined.
Feeder can be made from cable. It must be connected to brass or copper petals, which should already be attached to the output of the antenna.
If the resulting construction does not meet your expectations, for example, poor reception quality or the repeater is far away, you can equip the antenna with an amplifier - and as a result you will receive an active UHF antenna. It is used both in the city and in the country.
The simplest frame antenna UHF
This design resembles the number "zero". By the way, this is its gain. It is ideal for taking T2. This item is able to work better than the products that are offered in stores.
It is also called digital, because with it you can perfectly catch digital broadcasting. She narrowband, and this is a significant advantage. It works on the principle of a selective valve, which allows to speak about reliable protection against interference.
For assembly, you will need an ordinary coaxial cable with a resistance of 75 Ohms, as well as a regular television plug. Best of all to choose a cable with a large diameter. As a stand, you can use a cardboard box or something else.
How long the frame will be is determined using programs for calculating the parameters of the antennas. The material for making the frame can be used the same as in the cable.By the way, for calculations you need to know the frequency of digital broadcasting in your city.
The core cable in the frame design is not needed. The stripped wire is twisted together with the core and the sheathing of the frame. Then this connection needs to be soldered.
The design must be placed on a dielectric base. Better to keep her away from your tuner. It is important that there is no voltage at the antenna input.
So, we figured out how to do the UHF antenna with their own hands. As you can see, this is not a very difficult task. But now you can watch your favorite TV shows in digital quality. And such a structure is installed in the same way as a usual shop - on the roof. You can use screws or bolt connection. It should be installed in a safe place so that during gusts of wind it does not fly off with a piece of slate. It is desirable that the antenna was attached at the highest possible height. In this way, you will eliminate interference during cable or digital television.