Learn those who want to tune the antenna to television: digital gizmos are not created by nature. There are analog signals in the Universe, the power varies according to the quantum states of electrons. The transitions are so small that they seem continuous to a person. The signal can be represented by a certain number multiplied by elementary energy. We want to make it clear: the nature of a digital signal in the understanding of mankind is deprived, a digital antenna is not designed independently. It is possible to manufacture an antenna for receiving an analog signal carrying digital information.
Antennas for receiving a digital signal
Today it is exclusively digital television. However! Multiplexes, where programs are stamped with frames, contain radio broadcasts. We would like to clarify: in the current state of affairs, radio broadcasting has gone up, capturing the frequencies of the FM band, television has been completely replaced in the UHF. Explained by the features of modern life. The driver wants to listen to the radio, watch TV on the road. Have you seen long radio antennas? 34 MHz. Compare: USSR Channel I broadcast 50 MHz. Should everyone on the roof have an antenna two meters long to watch the center channel?
It's just ridiculous. In contrast to sticks, FM-UHF antennas are relatively small. Easily fit on the roof. Relieving the suffering of moviegoers, the channels carry one frequency. The picture is broken up by frames, it turns out that a lot of programs are available with a single antenna setting. Comfortable. We will see a lot of benefits of a technical solution from the phenomenon called today a digital multiplex. It becomes possible to accurately aim the antenna at the receiving frequency (which is a trivial UHF channel) in order to watch broadcasts, listen to the radio.
To solve the problem, a device that appears to be a "home-made digital antenna" is constructed by some. The antenna is ordinary, - we will add if we are interested in the type - linear. The design was chosen due to its small dimensions. One problem has been highlighted in the digital transmission…
Television is used to using horizontal polarization. Befell the fate of the digital multiplex. It turns out that the signal is caught then amazingly when the antenna line is perpendicular to the beam of the incoming signal. If we break the rule, power starts to be lost, reception worsens.
Reception of a digital signal by an antenna
Those wishing to receive a digital signal must understand the type of polarization of electromagnetic radiation. Discard satellite television broadcasting in frames, polarization, as Vladimir Volfovich says, is unequivocally horizontal. It is customary to catch the type of signal by television on a half-wave vibrator, there are two types of signal:
- Symmetric.
- Asymmetrical.
Let's explain. The first is formed by identical arms equal to a quarter of the wavelength. In total, half the wavelength is obtained. The signal core of the cable is connected to one shoulder, the shield is connected to the opposite. Shoulders in a row form a line, separated by a gap of 20 mm. To match, equalize the resistance of the antenna and cable, take the trouble to symmetrical. The first condition is ideally fulfilled, the second at UHF frequencies with decreasing wavelength plays a smaller value.
To make a digital antenna on your own, it is enough to equip the mast with a carrier plate, attach horizontally symmetrically two wire arms 3 mm thick, each quarter-wave long.
The resulting device is soldered onto a coaxial with a wave impedance of 75 ohms, as indicated above, the length of the drop cable is taken as low as possible, each meter eats up part of the useful power with losses. Only the length to the first amplifying stage plays a role. Supplying the roof with power, putting a purchased unit of the desired frequency, a bay in the corner, rolled up behind the TV, we make it impossible to spoil the reception. The overamp effect sometimes introduces unpleasant visual effects, the most famous being ghosting.
Another negative is possible. First, you should try the antenna without an amplifier. Reception will not be distorted by excess power. If unpleasant side effects are observed, it is worth trying to fight for quality improvement. It is important to direct the antenna more precisely. In the city, due to the multipath effect, in the village, due to the deviation of the direction of the wave from a straight line, the beam exit point is not where the compass points (according to the map). You should slightly move the antenna, setting the right direction, finding the best position.
Antenna reception
The half-wave vibrator of the design described above forms two main lobes in the radiation pattern. Spread 180 degrees. The radiation pattern is symmetrical in the horizontal plane. Therefore, we will improve the performance by installing a screen. An obvious solution, rarely seen for a simple reason: the antenna must catch a wide range, it is difficult to find the right distance. For a half-wave vibrator, the screen will not be a piece of conductive material - a pair of pieces of wire from which the arms are made. The distance between them is not so important, it should not be large. It is quite enough 5 centimeters up and down from the plane of the shoulders. The length of the screen exceeds the span of both, electrically located on the cable sheath.
The distance between the screen and the half-wave vibrator becomes important. We find it difficult to answer the correct answer, what abyss separates the details, for zigzag loop antennas, the value is 0.175 of the signal wavelength. We believe that amateurs have the right to try to experimentally choose the right distance, professionals have a chance to simulate the MMANA system. The former will get an acceptable result faster, the latter will be able to predict the final alignment of an arbitrary wavelength, which is preferable. Antenna modeling is not within the scope of the authors' interests, enthusiastic people are able to post the finished file, flavoring the comments with the fruit of technical thought. We believe the alignment will reduce the amount of interference.
Unbalanced digital antenna
As for the asymmetrical half-wave vibrator, it represents one shoulder. The second is replaced by "earth" (an infinite plane of zero potential), in practice there is simply nothing in this place. The manufacture of a half-wave asymmetric vibrator has been repeatedly shown by forums, the VashTechnik portal, and the network. Usually, the antenna serves as a room addition to a digital receiver, which is afraid to catch it on its own. To make the adjustment, the wavelength of the channel is calculated, divided by four. The cable screen is cleaned along the segment, the internal insulation is preserved - it will not interfere with reception.
An F-connector is screwed onto the end bent 90 degrees, which is inserted into the receiver, the TV socket (contain the receiving part of terrestrial digital television of the desired generation of the microcircuit). Almost all modern plasma panels have what they need inside. Tuning will take time, the channel frequency is known. You need to find out the number - visit the site http://rtrs.rf, look at the region, call the desired phone number. E-mail inquiries are accepted. Of course, if the region is deprived of digital television, no information can be found.
The given site is the official resource of the state unitary enterprise, which is entrusted with the task of digitizing the space of the Russian Federation. Ask, is a log-periodic digital antenna made by yourself? The answer is no need. The log-periodic antenna covers a large range, if you want to watch three Moscow multiplexes, take it. Having discarded the fear, use a wave channel type antenna, which differs from the log-periodic one in slightly worse range characteristics, and in a simpler design. The manufacturing technique was discussed, the provinces did not make much sense to waste time.
Readers understand: the device of a digital antenna is identical to the usual one. Polarization is linear horizontal, the frequency is determined by the channel. The principle of operation of a digital antenna is similar. Converting an electromagnetic wave into current inside a conductor. A feature of digital antennas is that they are precisely tuned to one frequency. The design is simple and efficient. Promising quality viewing (no visual or audio interference). Naturally, the TV, set-top box must decode the signal.
It remains to say goodbye to the readers. Today the amateur radio industry is a thing of the past, who will predict the awaiting humanity of tomorrow...
Television antenna - when the need arises for a choice, many find it difficult to decide which antenna to purchase to receive free digital television. Many are bought for publicity stunts for this reason, and there is a high probability of acquiring an unimportant antenna for a lot of money.
Hello dear readers! The author of this blog, Vitaly, is in touch! In my previous article on this topic, I talked about the antenna known as the "Key to Digital Television" And readers of this article very often ask the question of which antenna they should choose?
In order to answer most of these questions at once, it was decided to write another article in which there will be a selection of antennas recommended by me and other specialists. As well as some explanations and recommendations. Please read them carefully, perhaps this will remove some of your questions.
P.S. The article provides the names of the antennas, but please note that they may differ from manufacturer to manufacturer. This means that antennas of similar type and characteristics can be named LOCUS, DELTA, MERIDIAN, ETHER, etc. Therefore, it is not necessary to focus on the given names, look at the appearance!
All images in the article will be numbered, but this is only so that I can easily indicate the recommended antennas if this is asked in the future. There is no rating in this numbering! Just for convenience. So! Go!
Quick article navigation
indoor antennas
Indoor antenna Sirius 2.0 without amplifier. Designed for use in a stable signal area. These are settlements in which transmitting towers are located and at a short distance from them, 5-15 km. With line of sight. Signal gain 5 dB. Such antennas can also be made with an amplifier, but this does not make them suitable for difficult signal reception conditions.
Indoor antenna with amplifier DVS-Z2. Although this antenna has a large gain, up to 32 dB (due to the amplifier), there will be little sense from it. I also recommend using it in areas of reliable reception and at short distances from the tower of 5-15 km. With line of sight. It is good to use such an antenna in the city, to receive the reflected signal, an amplifier can be useful in this. And it is powered by a 5 volt antenna plug.
The next group of indoor antennas
They have approximately the same characteristics. These are passive (without amplifier) antennas. Signal gain 4-7 dB. But they will be somewhat more efficient than the antennas provided above.
These are not bad antennas, they can be successfully used to receive digital television in areas of both a strong signal and at some distance from TV towers. For example, I receive a signal on antennas of this kind from a distance of about 20 km. and from the first floor, but not everyone is so lucky!
All this depends on many factors. Transmitter power, terrain, clutter with high-rise buildings .... In general, if there is nothing very close on the way from you to the TV tower, then these antennas can quite cope.
Amplifier indoor antennas
These antennas do the same job as those without an amplifier. But an amplifier in some cases is useful and helps to stretch the attenuated signal to an acceptable level. They can be used not only in areas of good signal, but also, let's say, a slightly complicated or reflected signal.
But still, these are indoor antennas and this limits them. For example, if your windows do not face the TV tower, and there is no way to catch the reflected signal from the opposite side, they may be useless.
By the way! There is no need to evaluate the reflected signal, you can watch digital television perfectly on it.
Locus L999.06 Next — Active broadband antenna. Supplied disassembled. The amplifier is powered by 12 volts from an external power supply. UHF gain 23-27 dB.
Locus L922.06 Not a bad indoor antenna. It looks neat, there are options with and without an amplifier. The version with the amplifier is equipped with a power regulator, which can be very useful.
Delta K131A.02 and the other two from the above group are also active antennas, but with a 5 Volt amplifier supply voltage. It can be fed directly from the DVB-T2 set-top box or through a special injector from the USB port of the LCD TV. The gain of these antennas is up to 22-27 dB.
Active Antenna Cayman , — can be in two versions 1) Powered via antenna plug. 2) With an already built-in injector for USB power, which is very convenient for use with LCD TVs that have this port. There is no need to purchase an additional 5 volt power supply with an injector and take up another outlet.
Outdoor antennas for digital television
Let's move on to more serious designs, the task of which is to provide a high-quality signal where indoor antennas cannot cope. Gain from 19 dB to 35 dB.
These are antennas that can be used in more difficult conditions and at somewhat greater distances. If you notice, then they are structurally similar to indoor antennas, but only a little larger. And this is the important factor that makes them more powerful. The longer the arrow in the antenna, the greater the coefficient of its own gain. This is the gain that is achieved not due to the amplifier, but due to the design of the antenna. And the installed amplifier only “shakes” this signal even more.
In addition, street installation allows them to be more accurately directed to the TV tower bypassing obstacles in the form of walls.
hummingbird - Interesting antenna. Works in both meter and dmv bands. Its feature is an unusual design, which, with small dimensions, provides quite good signal reception. It is very convenient in urban environments and for searching for a reflected signal, the short length allows you to install it in a limited space. It has several modifications and can be supplied with an amplifier powered by both 12 and 5 volts.
Locus-14AF - This antenna also has several modifications, the designation AF - with an amplifier, F - without an amplifier. There is also Locus - 20 AF / F has a longer arrow, and therefore an even greater self-amplification factor. The amplifier operates on a voltage of 5 volts.
Delta H3111.02 - There are also options with and without an amplifier, in addition, it may be under a different name (depending on the manufacturer) and differ in the way the television cable is connected to it.
Meridian - 07 AF — Made from aluminium.
Antennas numbered 11-14 These are good antennas, and affordable, only Hummingbird will be a little more expensive
They can be used at distances up to 30 km. But then again, if there are factors that interfere with the passage of the signal, then even at shorter distances, an even more powerful antenna may be needed.
Powerful digital TV antenna
These antennas are good for long distances and even more difficult conditions, for example, if your house is in a strong lowland.
At what distance can they be used? For example, I had to put Ether 18AF (by the way, not the strongest in this trio) on a house located 45 kilometers from the TV tower. At the same time, the house stood in a lowland, and fixed the antenna on the ridge of the roof of the house, some kind of pin stuck out there, and fixed the antenna on it. Everything is well received!
Ether 18 — Antenna steel, painted with powder paint, there are options with an amplifier and without it. The letter A in the name indicates that the antenna is active, with an amplifier. If there is only F in the name, then this is an antenna without an amplifier. Meridian -12 AF / F antennas are also marked
Meridian-12 and Triton - Made of aluminum and even more powerful than Ether-18. The reason is not only in the material, but also in the design. For example, the Meridian antenna is about 1.5 meters long. And the "Triton" has short arrows, but there are already three of them. It adds up to one long one.
Active antennas from this trio have amplifiers powered by 5 volts. Which is convenient for use with DVB-T2 set-top boxes. The Triton antenna also has an injector for power supply via USB, which is indicated on the label. The gain of these antennas reaches 35 dB. by the amplifier. But thanks to their design, the amplifier has something to strengthen)))
THOSE. the antenna itself draws a signal from the air with a level of about 10-12 dB (this is called the antenna's own gain) And the amplifier already accelerates it to a level of 35 dB.
The most powerful antenna for DVB-T2
Well, if you carefully read the previous descriptions, then you should understand why these antennas are the most powerful ones presented in this review.
For example, the GoldMaster-GM500 antenna is a passive antenna, without an amplifier. But the coefficient of its own gain, only due to the design of as much as 22 dB. Such amplification is given by mid-range antennas, and then at the expense of the amplifier. Here it is in its purest form!
The following antennas from this "red zone" are just as effective, plus they are also active. Their amplifiers are powered by 5 volts. Ie they are sharpened for digital set-top boxes. Or, if you don’t use a set-top box, since you bought a TV set with DVB-T2, then you will need either a separate power supply for antennas, 5 volts or an injector for USB power.
This is the class of antennas that you need to take if you live at a distance of 50 km or more from the transmitting tower and have a very difficult area for receiving a TV signal.
Why you shouldn't aim for an antenna with an amplifier
It is noticed that the word "Amplifier" has some kind of magical property! And when a person chooses an antenna, he prefers just such active antennas. Why is this an erroneous point of view?
- In the zone of reliable reception, the amplifier can lead to the fact that your TV / set-top box will not receive anything at all! Cause, overamplification of the signal!
- The amplifier amplifies not only the useful signal, but also radio noise. And it is the design of the antenna that draws the useful signal!
- The amplifier is always the weak link in the design of the antenna. It breaks down, it is hit by a thunderstorm, it oxidizes from moisture. As a result, periodic intervention in the repair of the antenna is required.
- It is required to provide power to the amplifier located in the antenna, and this is another additional weak link, adapters fail and require replacement. In addition, one more connection point, socket or USB port is required, and this is not always convenient!
- In the case of connection, this is much easier to do with an antenna that does not have an amplifier.
When You Need an Amplifier
- If the total length of the television cable exceeds several tens of meters.
- If you live at a great distance from the transmitting tower, in a weak signal area, and the design of the antenna itself does not allow you to “pull out” the signal to the desired level.
Conclusion! - If at your place of residence it is possible to confidently receive a signal on an antenna without an amplifier, always strive for an antenna without an amplifier!
How to supply power to an active antenna amplifier
There are several ways to supply power to the antenna amplifier.
- If you use a digital set-top box, then power is supplied directly from it, via the antenna cable. You don't have to be smart about anything. Just go to the set-top box menu and find the item “Ant power. on "In different models of set-top boxes, this inscription may differ, but the essence is the same. Turn on the power to the antenna! Even if the amplifier in the antenna is 12 volts, often 5 volts from the set-top box will be enough.
- If you do not use a set-top box, then to power the active antenna you will need either a special adapter with an injector that can be connected to the USB port of the TV and power the antenna in this way. Or purchase a USB-powered antenna. These methods are very convenient for LCD TVs, especially those hanging on the wall.
- The classic way, through a power supply for antennas with a voltage corresponding to the amplifier.
Well, I guess I'll end here! In the "Television" section of this blog, there are many more articles on the topic of antennas, digital set-top boxes and television.
Dear readers of the NskTarelka.ru blog, if you are interested in the answer to the question - Which antenna to choose for digital terrestrial TV? Well, this article is just for you.
Before we start talking about choosing a television antenna for DVB-T2 digital television, let's talk a little about terrestrial television itself.
Terrestrial television - broadcasting formats, signal broadcasting
Television free channels, which we watch by receiving a signal on indoor or outdoor (street) antennas, are the same terrestrial television. The television (radio) signal is broadcast from the repeater to the air, that is, to the surrounding space, by means of electromagnetic waves. We, as users, using terrestrial antennas, receive this television signal.
To transmit a television signal, meter MV (VHF) and decimeter UHF (UHF) waves are used.
Digital terrestrial television of the DVB-T2 standard is broadcast on the air via UHF decimeter waves (UHF). Accordingly, in order to watch the "figure" you need to have the "correct" antenna. It must be either all-wave (MV (VHF) + UHF (UHF)), or UHF decimeter range (UHF). With an antenna receiving only MV (VHF), the range of viewing digital terrestrial television will not be possible.
MV and UHF are the ultra-short wave (VHF) bands allocated for the transmission of a television signal. Frequency band from 48 to 862 MHz with conditional division into 5 bands combined into two groups:
- 1-12 meter channels or MV (VHF), bands I, II, III (47-160 MHz);
- 21-60 channels decimeter, in a different way UHF (UHF), bands IV, V. (470-862 MHz).
Broadcasting of analog terrestrial television is in both bands, both in MV and UHF. Previously, it was planned to turn off analog TV in Russia until the end of 2015, but now the deadlines have been moved to 2018.
Which antenna to choose for digital TV?
Since we choose an antenna for digital TV, it is understood that we have a DVB-T2 set-top box, or a TV with a built-in DVB-T2 tuner. We have accurate information that in the place we are interested in, where we want to enjoy watching digital television, it is already available.
Not that I am “Captain Obvious” or as if for those who are “in the tank”, but you never know, just in case. Suddenly, one of the readers is not in the know, and thinks that to watch digital television, the “necessary” antenna is enough. No, it's not.
So, before spending money on an antenna, we check what is available. It is quite possible, it is enough to connect to the old antenna and everything will work.
If your antenna previously received channels of analog terrestrial television going in the UHF range, respectively, digital television, it is quite possible that it will work without problems. It is enough to connect everything and scan the channels.
Why did I write quite possibly? Because there are some nuances. There are such concepts as the difference in altitude between your location and available repeaters that transmit a television signal.
Collective Antenna
First of all, if you live in an apartment building and it uses a collective antenna, try to connect through it. If everything works, great.
If not, contact the organization serving you with a request to deal with the television signal or install your own.
indoor antenna
Whether a room antenna is enough for high-quality digital television reception depends on the remoteness of the repeater (transmitter), as well as its power. The power of the transmitter of interest can be found at the counseling center.
Or, as an option, on the RTRS website, in the upper right corner, click on "Select Region", select your region (republic, region, district). After that, click on "Digital TV" in the menu. On the page that opens, click on the link "Objects of digital broadcasting of the RTRS-1 package". In the table that opens, there will be information about the power of the transmitters.
On average, the radius of the coverage area of a DVB-T2 digital transmitter in the decimeter range, under the most ideal conditions (the height of the receiving antenna is 10 m, flat terrain, line of sight):
- 10 W - about 3 km.
- 50 W - about 5 km.
-100 W - about 15 km.
- 500 W - about 25 km.
-1 kW - about 30-35 km.
- 2 kW - about 35-40 km.
- 5 kW - about 40 - 50 km.
RTRS group VKontakte
When the TV tower is in direct line of sight from the window, even reception without an antenna is possible. It is enough to connect a piece of coaxial cable, popularly called antenna.
When connecting one TV, choosing between the options of a passive antenna or an active one, we give preference to a passive one. Passive is the one without an amplifier. Active with amplifier.
To broadcast the DVB-T2 standard to several TVs, an active antenna is purchased. Since the signal is diluted with a divider to two or more TVs, losses occur that are compensated by the amplifier. If there is a choice, an antenna with adjustable signal gain is purchased. Thanks to this, we can control the signal amplification power.
The proposed choice of indoor antennas can give you a headache. Which one to buy?
The upper price range is usually not good. Many expensive ones are not good at all.
No need to focus on those promoted as specialized for DVB-T2. Often this is beautiful trash for big money. There are no specialized DVB-T2 antennas - this is a marketing ploy.
As I said above, the television signal broadcasts at the frequencies of the meter - MV (VHF), and decimeter UHF (UHF) VHF bands. To date, the UHF range has been allocated to the DVB-T2 digital terrestrial television standard. And the UHF band antenna will be correct, and not the DVB-T2 antenna.
Therefore, if a super-duper for DVB-T2 is written on the box, this does not mean anything.
If the TV tower is not visible from your window, but it is relatively close, it is advisable to purchase a directional indoor antenna. The signal in this case comes to you reflected from other houses - a directional indoor antenna is the best option here.
In terms of price and quality ratio, an excellent option would be to purchase one of the brands - LOCUS (Locus) Moscow or Delta St. Petersburg.
If possible, before buying an indoor antenna, try to borrow it to test the signal from friends. Or if you buy in a specialized store, you may be able to agree on a return with a replacement for a street one.
Outdoor (street) antenna
When it’s impossible to catch a room antenna or, due to the distance, it doesn’t even make sense to try, we use an outdoor (street) antenna. If there is an old one that is already on the roof or on the balcony, or outside the window, first we try to catch it. No antenna, let's go to the store.
What should be guided by when choosing an outdoor (street) antenna? To begin with, using the DVB-T2 digital television coverage area map, we determine the distance from the antenna installation site, to the repeater from which we plan to catch the signal.
When choosing an antenna, we take into account the signal strength of the repeater. The power of the tower determines its reception area.
If the terrain is not flat, it makes sense to find out the height difference between your location and the available repeaters transmitting a television signal.
When connecting one TV, as in the case of an indoor antenna, choosing a passive outdoor antenna is preferable to choosing an active one.
When wiring a signal to two or more TVs, we use an active antenna, that is, with an amplifier. If possible, we purchase it with adjustable gain.
When buying, we prefer an antenna made only for the decimeter range - UHF (UHF). If you plan to watch analog channels in parallel with digital ones, until they are turned off, purchase an all-wave channel that supports both ranges. And meter - MV (VHF), and decimeter UHF (UHF).
In addition to the moment of choosing the parameters of the antenna, remember the equally important thing to consider during installation. It is about the height of the installed antenna. There are cases, and they are far from isolated, when the most powerful antenna for receiving a signal will not help either. But it is enough to raise the antenna a couple of meters in height, and it turns out that the old, less powerful one would be enough.
International standards for the zone of reliable reception of television broadcasting are published based on the calculation of the height of the antenna suspension:
For rural areas at least 10 m
- suburb, not less than 20 m
- city 30 m
Therefore, the best solution for hanging the antenna is the highest point, i.e. the roof.
And at the end of the article, I bring to your attention a video from RTRS - How to set up an antenna for receiving digital terrestrial TV. Possible problems and ways to solve them.
In contact with
Analogue broadcasting, which was used earlier, has been completely discontinued since 2009. The change in format to digital created the need for an appropriate receiving device. Digital TV broadcasting is carried out in the UHF range, which is capable of accommodating many channels, with compactness and high signal quality. The increased transmission level reduced the maintenance costs of the equipment, made it more resistant to interference, although not all problems were completely solved. In rural areas, signal reception is almost impossible, and in a big city it becomes more difficult due to the ability of reinforced concrete structures of multi-storey buildings to shield the signal. For confident reception, it is quite possible to make an antenna for digital TV with your own hands, since its cost in the store is quite high.
The principle of operation of a digital antenna
A digital signal differs from an analog one in that it transmits not the wave itself, but information about it.. That is, it consists of a continuous stream of "coordinates" of points of a specific graph of a sinusoid transmitted by conventional analog devices. This makes it possible to significantly reduce interference and improve the quality of signal transmission, since a failure in the transmission of information does not cause big problems and is easily corrected when the signal is decoded in the receiver. Otherwise, the transmission technology remains the same - electromagnetic oscillations are radiated from the transmitter into space, they are received by antennas in the line of sight, on the circuits of which a small voltage appears, which is transmitted to the decoding device of the TV and turns into an image and sound.
To receive decimeter waves, a small antenna size is required, which distinguishes the devices from the previously used huge antennas that filled the roofs of houses. The dimensions of digital antennas are quite compact, so they can be freely placed in an apartment, on a balcony or in another place convenient for the owner and providing high-quality reception. A homemade antenna has a simple design and is quite affordable for people without special training, who have only basic knowledge.
We make a loop antenna with our own hands
The round antenna for digital TV has the highest input impedanceThe loop antenna is one of the simplest options. At the same time, the resistance to interference of such a device is very high, because the design combines a receiving antenna and an interference filter. The name "framework" speaks of a specific configuration - it is a closed contour in the form of a round or rectangular frame. Made from copper wire. Also, as an option, you can use a piece of antenna cable (RG6), freed from vinyl insulation.
Calculation
To calculate the loop antenna, you only need to determine the length of the wire from which the frame is made. The calculation formula looks like this:
where LR is the length of the wire in the loop,
f - wave coefficient, which is the arithmetic mean between the values of the boundaries of the wave range. For example, if broadcasting is carried out in the range of 568–720 MHz, then f = 568 + 720 / 2 = 644.
You can find out the required ranges on the websites of transmission companies or from other sources - this information is freely distributed. The start and end frequencies are used for the calculation. If there is no final frequency, then the value of f is taken equal to the initial frequency.
Some experts give another version of the formula, according to which the side of the square frame is 0.254 of the wavelength (or f). That is, the value obtained from the calculation according to the first formula must be increased by 1.5%. The difference is insignificant, but in some cases it is important.
To make an antenna you will need:
- pliers;
- Ruler;
- soldering iron;
- A clerical knife for stripping insulation (if an antenna cable is used).
Only the most basic tools are listed, depending on the skills and capabilities of the user, other devices that are more suitable for any purpose can be used.
Manufacturing instructions
Making a loop antenna is not difficult. You will need to do the following:
- Cut a piece of wire to the desired length. Experienced users are advised to first cut off a piece a little longer than the calculation requires, so that it is possible to more accurately adjust the length when forming the antenna configuration.
- Give the antenna the desired shape. If a round loop is used, then it is necessary to make the circle as even as possible; for a square frame, the length of the sides must be precisely maintained.
- The ends of the frame are connected to the antenna wire from the TV: one end to the braid, the other to the central core. A soldering iron or a mounting block with terminal clamps is required for this task.
- It remains to install the device in the most suitable place for reception and adjust the position.
How to make a Kharchenko antenna
You can make such an antenna with your own hands for receiving Wi-Fi The design was proposed by K.P. Kharchenko in 1961. The main task is to receive television programs, but practice has shown the high suitability and versatility of the invention. Kharchenko's external antenna has the shape of a figure-eight with an open middle. It consists of two squares, and the connection to the antenna wire is made at midpoints. Thus, we have a closed loop of thick copper wire, which has a specific shape. The difference from the frame structure lies precisely in a more complex configuration, which allows you to get a stable and confident signal reception, noise immunity and reliability. Its feature is broadband and the ability to receive both television and radio signals. It all depends on the location of the antenna - the vertical one receives the TV signal, the horizontal one - the radio.
The shape of the eight is not the only possible option, you can increase the number of squares formed. Variants with the formation of circles, triangles, etc. are also known. The figure eight is used because of the ease of manufacture and configuration, as well as the absence of interference.
Calculation
Self-calculation of the Kharchenko antenna is not difficult, but includes the determination of many quantities. You will need to calculate the length of the side of the square, the size of the reflector (reflector), the total length of the eight from the top to the bottom, the gap between the reflector and the antenna, etc. Therefore, the simplest and most reliable solution will be to use an online calculator, of which there are many on the network. To get a more accurate result, you can try to calculate on several services and compare the data.
Necessary tools and materials
To assemble the Kharchenko antenna you will need:
- Thick copper wire with a cross section of about 4 mm 2;
- Aluminum plate for reflector (reflector). In its absence, a metal grate (mesh) can be used as a reflector;
- Pliers, hammer, screwdriver;
- Electric drill with a set of drills;
- Soldering iron, terminal block;
- A metal pipe or wooden long bars for the manufacture of a supporting structure (mast).
There are many design options for the manufacture of which you can use various additional devices. If necessary, they are involved in the working order.
Manufacturing instructions
- According to the calculated data, an eight is made.
- The connection at the middle point is soldered, the second point is tinned for subsequent power connection.
- Holes are drilled in the reflector plate, into which bosses are installed for mounting the antenna.
- It is fixed on the support bosses, a wire is soldered to the central points.
- The reflector plate is attached to the mast. For this, screws or clamps are used if it is made of a metal pipe.
- The mast with the antenna is installed in the allotted place.
- Connected to the TV, the optimal position is adjusted.
Other options
Design variant of the Sotnikov antenna of three squares The options discussed are not the only possible ones. There are many designs of antennas for receiving a television signal.
The following can be distinguished:
- Three-element wave channel. It is a rather complex structure made of a horizontal bar, on which two transverse strips and a T-shaped frame are installed. A variant of this design is a four-element wave channel containing three crossbars and one T-shaped structure.
- Double square (Sotnikov antenna). It has a gain factor of 10–13 dB; it consists of two square frames arranged in parallel and connected to each other by a cross member. A variant of the design is a triple square, the authorship of which belongs to the same Sotnikov. The amplifying ability is higher - in the region of 14–15 dB.
- Antenna Turkina. The gain that this design has is more than 15 dB. It consists of six rings of different diameters, fixed on a horizontal dielectric support rod. The device requires a rather careful calculation of the diameter of the rings and the distance between them.
Video: How to make a do-it-yourself digital TV antenna
The transition of television to digital format occurred in order to eliminate interference, increase the quality of transmission, more confident reception and compact equipment. The need to use your own antenna is due to a large amount of interference or distance from the repeater. In the absence of the possibility of acquiring a factory-made sample, which is quite expensive and not always available for sale, it is quite possible to make a home-made device, since this is not particularly difficult.
In the days of huge tube TVs, a good antenna for high-quality analog TV reception was in short supply. Those that could be bought in stores were not of high quality. Therefore, people made UHF television antennas with their own hands. Today, many are interested in homemade devices. And even when digital technologies are everywhere, this interest does not fade away.
Digital era
This era also affected television. Today, T2 broadcasting is developing especially widely. It has its own characteristics. In those places where the signal level slightly exceeds the interference, a fairly high-quality reception is obtained. There is simply no further signal. The digital signal does not care about interference, however, in a situation of cable mismatch or various phase distortions, almost anywhere in the transmitting or receiving path, the picture can go in squares even with a strong signal level.
In modern television, other changes have taken place. So, all broadcasting is carried out in the UHF band, the transmitters have good coverage. The conditions under which radio waves propagate through cities have changed dramatically.
Antenna parameters
Before you start manufacturing, you need to determine 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 power at the input of the antenna used. All this will work if each of the antennas creates the values of the intensity and flux density with the same parameters. The value of this coefficient is dimensionless.
The directional factor is the ratio of the field strength that the antenna produces to the field strength in any direction.
It must be remembered that parameters such as KU and KND are not interconnected. There is a UHF antenna for digital TV, which has a very high directivity. However, its enhancement 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 level of amplification.
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 will receive a complete calculation of the UHF antenna, so that you can then assemble it.
Manufacturing nuances
Any structural element in which signal currents flow must be connected using a soldering iron or a welding machine. Such a node, if it is in the open air, suffers from a breakdown in contact. From this, various antenna parameters and the reception level can become significantly worse.
This is especially true for points with zero potentials. According to experts, voltage can be observed in them, as well as current antinode. To be more precise, this is the maximum current value. Is it available at zero voltages? No wonder.
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?
Do-it-yourself UHF antenna is not very easy to make. This involves working with a soldering iron. Modern television cable manufacturers no longer make it copper. Now there is an inexpensive alloy that is resistant to corrosion. These materials are difficult 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 spare the paste when soldering. The solder will lie correctly only if it is under a layer of boiled flux.
Catch T2
In order to enjoy digital TV, 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 ones are too expensive and meaningless.
Now we will learn how to catch T2 on a completely homemade design. Homemade UHF antenna - it's simple, cheap, high quality. Try it yourself.
The simplest antenna
To assemble this design, you will not even need to go to the store. For its manufacture, a conventional antenna cable is sufficient. You need 530 mm of wire for the ring and 175 mm from which the loop will be made.
The TV antenna itself is a ring of cable. The ends must be stripped, and then connected to the loop. And to the latter you need to solder a cable that connects to the T2 tuner. So, on the ring, the screen and the central core are connected to the screens of the loop. At the last, the central veins are also connected. And the cable to the tuner is soldered as standard to the screen and the central core.
So we got the UHF antenna, made with our own hands. Its construction turned out to be very cheap and practical. And it works no worse than expensive store options. It must be fixed on plywood or plexiglass. For this, construction clamps are perfect.
"People's" antenna
This design is an aluminum disc. 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 disk (10 mm wide). In the place where he drank, you should install a printed circuit board made of textolite. It should be 1 mm thick.
The board must have holes for the M3 screws. The board must be glued to the disk. Then you need to solder the cable leads to it. The central core should be soldered to one side of the disk, the screen to the other. In terms of quality, such a TV antenna will receive better with two discs, especially if it is far from the TV repeater.
Universal Antenna
Nothing supernatural will be used to make this design. We will make it from various improvised materials. However, although it is homemade, it will work perfectly in the entire decimeter range. So, this UHF antenna, quickly made with your own hands, is in no way inferior to store-bought, more expensive designs. To receive T2, it will be enough completely.
So, to assemble this design, you will 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 strips of textolite or getinax, always with foil.
Our cans need to be connected to the textolite strips using a soldering iron. The plate of this material, which will connect the containers at the top, must be completely covered with 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 cannot find suitable jars, then you can use containers with a smaller diameter. However, then the foil will have to be cut on the upper connecting plate as well.
"Beer" antenna
Love to drink beer? Don't throw away cans. You can make a good antenna out of them. To do this, you need to fix two beer cans on any dielectric material.
First you need to choose the right cable, and then bring it to mind. To do this, the cable must be stripped. You will see shielding foil. There will be a protective layer underneath. 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 carefully twisted to end up with a branch. The protective layer for the central core must be cleaned by 1 cm.
On the other hand, you need to solder the plug for the TV to the cable. 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 liter. However, good German beer in such cans is expensive, and domestic beer is not sold.
Banks must be opened very carefully. Then you need to free the container from the contents, and then dry it well. Next, use a self-tapping screw to connect our screen on the cable and the jar. To the second you need to fasten the central core.
For a better image quality, it is better to connect the containers and the cable with a soldering iron.
It is necessary to fix the banks on some dielectric material. It should be noted that they should be located on the same straight line. The distance between them depends on the capacity. All this is selected only by experience.
Zigzag
The UHF zigzag antenna has the simplest possible 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 the size of the conductors that will form the basis of the web. There is a dependency here. The greater the width or thickness of the conductors, the better the antenna will be matched to the feeder. In general, any conductors can be used to make a web. For this, plates, and tubes, and corners, and much more are suitable.
In order to increase the directivity of such an antenna, it is permissible to use a flat screen, which will play the role of a reflector. The latter will reflect high-frequency energy towards the antenna. Such screens are often large, 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 that are connected in the same plane. For design reasons, it is not necessary to make a screen that is too dense. The conductors from which the screen itself will be made are attached by welding or soldering to a metal frame.
This design is made very simply. It works well in the UHF range. In the USSR, it was a real folk 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, then the structure should be soldered along the contour.
The cable must not be bent sharply. How to carry out this element, you can see in the pictures presented.
It must be guided in such a way that it reaches the side corner, but does not go beyond the antenna or side square.
Indoor antenna MV UHF
This design is designed for easy and reliable 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 antenna.
The design is a frame in the form of a rhombus. There should be two. One acts as a vibrator, the second works as a reflector. To receive T2, it is necessary that the side of our rhombus is approximately 140 mm, and the distance between them is 100 mm.
After the frame is made and the structure becomes rigid, a dielectric is mounted between the two ends of our rod. It could be anything. Shape and size are completely irrelevant. The distance between two points of the bars should be approximately 20 mm. The upper parts of our rhombuses need to be connected.
The feeder can be made from a cable. It must be connected to brass or copper petals, which should already be fixed on the antenna output.
If the resulting design does not meet your expectations, for example, poor reception quality or the repeater is far away, you can supply the antenna with an amplifier, and as a result you will get an active UHF antenna. It is used both in the city and in the country.
The simplest UHF loop antenna
This design resembles the number "zero". By the way, this is the coefficient of its amplification. It is ideal for T2 reception. This part 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 broadcasts. It is narrowband, and this is a significant advantage. It works on the principle of a selective valve, which allows us to talk 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 TV plug. It is better to choose a cable with a large diameter of all options. As a stand, you can use a cardboard box or something else.
How long the frame will be, we determine using programs for calculating antenna parameters. The material for the manufacture of the frame can be used the same as in the cable. By the way, for calculations you need to know the frequencies of digital broadcasting in your city.
The central core of the cable in the frame design is not needed. The stripped wire is twisted together with the core and braid of the frame. Then this connection must be soldered.
The structure must be placed on a dielectric base. Better to keep it away from your tuner. It is important that there is no voltage at the antenna input.
So, we found out how the UHF antenna is made with our own hands. As you can see, this is not such a difficult task. But now you can watch your favorite TV shows in digital quality. And such a design is installed in the same way as a regular store - on the roof. You can use screws or bolted connection. It should be installed in a safe place so that during gusts of wind it does not fly off along with a piece of slate. It is desirable that the antenna is mounted at the highest possible height. Thus, you will exclude the appearance of interference during the display of cable or digital television.
