Modern terrestrial television broadcasting is digital, that is, the broadcast of a TV signal is carried out by electromagnetic waves. But in order for certain channels to be available to the population, indoor antennas for TVs are needed. There are a large number of them. How are they different and how to use them?
What is the specificity?
Indoor antennas are installed indoors and are able to receive signals in areas of reliable reception. Most modern models can pick up a signal in the most popular ranges, besides, they are cheap, so they are popular with buyers. In order for the chosen accessory to really help catch the signal, several factors must be taken into account when choosing:
- distance from the repeater;
- transmitter power;
- building density;
- landscape features;
- floor;
- the level of interference (domestic and industrial).
The closer indoor TV antennas are to the transmitting station, the better signal reception will be.
Passive or active?
Depending on the type of signal amplification, all antennas are passive, active and directional, which are distinguished by a high gain. When using passive designs, signal reception and amplification will be provided by the geometry of the antenna itself. Its features include:
- independence from the electrical network and the absence of active amplification elements and electronic components;
- does not create interference and noise when receiving a signal.
But in some cases, the capabilities of a passive antenna are insufficient to receive a high-quality signal. A passive indoor antenna for a TV receives mixed reviews, since it is only suitable for receiving a signal at short distances and provided that the buildings are low-rise.
The peculiarity of active antennas is that they amplify the received signal not only due to the design features, but also thanks to the electronic amplifier that is supplied in the kit. It is mounted either in the antenna housing itself, or separately, and power is supplied from the mains through an adapter.
If you want to receive digital terrestrial TV, you need an amplifier for the TV indoor antenna. This option is good even if the distance from the transmitting center is significant. On the other hand, the amplifier may generate its own noise and interference.
What are the frequencies?
Depending on the received frequencies, antennas are channel, band or all-wave. The first ones receive separate frequency channels and are used in special conditions. Band antennas can receive signals from MV or UHF - this version is sufficient for receiving digital television. All-wave indoor antennas for TVs are capable of receiving signals of both ranges - both MV and UHF, and therefore are suitable for use in our country.
Specifications
Any antenna is characterized by special technical data and parameters. When buying, you need to pay attention first of all to the gain, which is measured in decibels: the higher it is, the better the antenna will amplify the television signal. True, this does not always affect the image quality.
To make the TV indoor antenna workable, it is important to connect it correctly. For this, a coaxial cable is used, which is supplied in the kit. The cable must have a characteristic impedance of 75 ohms and be made of high quality materials with a dense sheath.
The high demand for indoor antennas is due to the fact that they are small in size, conveniently located on the TV or next to it, simply connect and provide high-quality signal reception.
Popular models
The best is considered to be a conventional T2 antenna, which is suitable for UHF frequencies. Its popularity is due to the fact that digital terrestrial channels are transmitted in HD quality. Among the popular and affordable ones, the following designs can be noted:
- REMO BAS-5315USB. This active antenna is designed to be placed in a room and provides reliable signal reception. Sophisticated design features ensure optimal performance with analog and digital TV signals. Powered by a TV USB injector or power supply. The antenna has a shell made of high quality materials, which are durable and safe to use. The cost is 1199 rubles.
- REMO BAS-5310USB HORIZON. This antenna stably receives the signal of television broadcasts in the range from 21 to 69 channels. An interesting design allows you to effectively fit this structure into the interior of the room. The cost of the model is 799 rubles.
- DENN DAA210 is the cheapest antenna, which costs only 290 rubles. Ideal for compact installation in a room, it has an active amplifier and built-in noise cancellation, so it receives a high quality signal without interference.
- VIVANCO. For 1300 rubles, you can buy a VIVANCO universal indoor antenna with an amplifier, which copes with the reception of digital and analog signals at various frequencies.
These are the most popular brands of antennas that are in demand among buyers and have proven to be the best. The best indoor TV antenna is one that can receive a digital signal while maintaining good picture and sound quality.
Features of operation
Indoor TV antennas are presented in a wide variety. But in order for them to show a stable signal, a competent installation plays an important role. First, the structure should be directed towards the TV tower. Secondly, you should first connect the antenna without an amplifier. If the image and signal reception are of high quality, you can do without amplification.
In general, indoor antennas are the most budgetary ones; they attract attention with their compact size, ease of transportation and ease of installation. Most modern models are either frame or rod, and they differ in the range: the first work in decimeter, the second - in meter. The right choice will allow you to watch your favorite shows and movies in high quality.
- do not use purchased when your grandfather went to first grade;
- don't buy the cheapest one with virtually no braid. Choose normal ones;
- do not shorten as much as possible;
- do not make sharp creases;
- do not twist the excess into a bay.
Even if you connect the pieces with a standard coaxial connector, the signal quality is guaranteed to deteriorate.
Using the amplifier
This inexpensive summer cottage antenna gives a good result. If you plan to receive this antenna only, then two of its long side "mustaches" can be unscrewed.
Wave channel
They give good results, especially for remote signal reception when it is weak enough.
Polish
Many TV viewers use a "Polish" antenna - a grid and four rows of antennae. It doesn't matter where it was made, they used to call it "Polish", and sometimes "mesh". Very often, it demonstrates not the best characteristics for receiving a digital signal.
In general, for admission to the country , very sensitive. If the reception of a digital signal on it in your area turns out to be normal, then you are just in luck. The amplifier of this antenna can be powered by a 5 volt power supply, which can be taken from a digital tuner, and then you do not need to use an additional power supply.
Zigzag
indoor antenna performs well for. Even if you paid dearly for it, the result may be zero.
If you want only a room antenna as a terrestrial antenna for a summer residence, you may be "advised" to buy it at a higher price and "better". But if you hope that she will start giving you a wonderful signal in your room, then this hope is in vain. If the signal in the house is bad, no antenna will help. External is the solution to the problem if there is no reception in the room.
Satellite
Remember? We're talking ethereal, so forget satellites. You will not receive terrestrial television in the DVB-T2 standard through a satellite tuner. You will not be connecting a T2 tuner to. We receive the T2 signal from the nearest broadcasting tower in the decimeter range. On an ordinary terrestrial antenna for a summer residence, not a "plate".
Let's describe in a few words the wonderful qualities of digital television. The technology differs from the traditional form of the transmitted signal. Analog systems change the field strength continuously, digital each pixel value is encoded with ones, zeros. An indoor digital TV antenna accepts any signal. Reception does not care about coding, polarization plays a decisive role.
Reason for mastering digital broadcasting
The digital signal is very stable. The ones and zeros are sometimes additionally encrypted with a code known to the recipient. Against the background of noise, the equipment is scanning the received signals, the correspondence of the sample to the incoming wave gives a peak that is many times higher than the noise level. Digital broadcasting will allow the power of the transmitters to be reduced.
It is clear that in conditions of an increased background of electromagnetic radiation, quality is very important. This explains the obvious fact: digital television is gaining popularity.
Let's discuss quality separately. The encoded signal faithfully reproduces the colors of the pixels. The picture looks real, similar performance is difficult to achieve using analog transmission. Billions of colors can be recognized from the signal received by the antenna for digital television. You may not notice the differences on the screen just because it is not profitable for free channels to increase the cost of equipment, purchase a double frequency band in order to please the user with the Diamond Color shades presentation system.
Digital television has succeeded in narrowing the signal spectrum. Let us discuss the physical meaning of the spectrum. The fact of conversion means: previously there were 10 analog channels, now there will be about 35 digital standard definition.
There are three side effects that are useful to both sides of the client-provider property link:
- Protection of the channel from viewers who have delayed the subscription fee. A valuable plus given by digital television antennas. Watch the necessary, cutting off the unnecessary.
- Integration of broadcasting with the Internet. Now it is permissible to use special provider keys without buying additional equipment (receiver). The satellite passcode is transmitted by the internet network by the service provider's server. Usually there is a free test mode for watching satellite digital television.
- We will consider interactivity as a novelty of video playback technologies. Digital options given out on DVD live.
A dozen of advantages are demonstrated by digital TV antennas. If logical arguments do not convince you to choose a number, know: by 2015, 100% of broadcasting was planned to be digital.
Why conventional antennas cannot be used
Wide-range devices underestimate the gain by catching a larger spectrum of frequencies. Lack does not always turn into a disaster. Residents of problem regions with a weak signal will have to think.
Signal polarization
A constant electric field is not carried by the ether. Only dynamic systems are characterized by the property of mobility. The world allows a change in the electric field to cause an adequate magnetic response. It turns out a wave that resembles a New Year's garland twisted, cut along the paper. It narrows and expands.
The electromagnetic wave, detect the phenomenon of the human eye, looks similar. Two school sine waves, mutually perpendicular. The first chose a horizontal plane, the other - a vertical one. One is the amplitude of the electric field, the other is the magnetic. It is customary to divide the polarization:
- Vertical.
- Horizontal.
Polarization is characterized by a spatial figure that describes the vector of the electric field amplitude. Owners of smart TVs catch the horizontal or vertical (radio) plane. Digital broadcasting uses the simplest waveform.
The polarization formation process is performed entirely by the transmitting antenna. The reception area must have equivalent characteristics. Identity is called electromagnetic compatibility.
The case is not limited to the considered case, spiral antennas are circularly polarized, right-left. Determined by the direction of the twist of the turns. Helix antennas are not compatible with linear antennas.
Elliptical polarization occurs, circular is considered a special case. You see - simple information. It remains to add - the vectors of the amplitude of the electric, magnetic fields do not occupy perpendicular planes, continuously rotating. It resembles a picture of a human DNA strand.
Frequency band
Let's consider the concept of frequency. Schoolchildren saw a sine wave. The period of the function is contained in the denominator, the unit is in the numerator, together the frequency is obtained. Shows the rate of change of the amplitude of the electric, magnetic fields. Occupies perpendicular planes. Circular polarization is characterized by frequency, the relationship is more complex.
Real signals differ from sinusoidal waveforms. A short time interval allows you to consider the field approximately (short time). The real satellite signal occupies a fixed frequency interval. The total is summed up by adding the elementary harmonics (sinusoids). The graph represents the process as a function of the amplitude of single sinusoids (volts) versus frequency (hertz). The representation is called the spectrum of the signal, the horizontal segment occupied is the bandwidth of the signal. Let's add - in digital television, harmonics are separated by a strictly defined distance. The spectrum is discrete.
Antenna for receiving digital television is characterized by polarization, operating frequency band. You cannot use arbitrary modification. It is impossible to cover the frequency band occupied by digital television with one antenna.
Digital broadcasting is satellite, terrestrial, cable. Today the second type of television is being touched upon. The satellite signal is received by parabolic, toroidal antennas.
Nominal broadcasting frequencies are prescribed by GOST 7845-92. According to the manuscript, 5 bands are assigned to digital television. Stay within the range of 48 - 790 MHz. This swing corresponds to sixty channels. Antennas for digital terrestrial television can overlap this list 100% or catch one broadcast, VHF or UHF.
The standard clearly indicates the carrier frequencies for picture and sound. The polarization in digital television antennas is horizontal, but the standard also regulates the use of vertical polarization. But in any case, linear. The image carrier is modulated in amplitude and the carrier in frequency is modulated. In this, digital television is not far from analog. The lower sideband is suppressed to save power and reduce the bandwidth of the transmitter and receiver paths.
A 75 ohm coaxial cable is required for device connections. Accordingly, both the input and output resistances of the devices are close to this value.
Antennas
Antennas for digital television follow the requirements specified in the previous section. Available models:
- room;
- street;
- hybrid.
Which antenna you need for digital television is relatively easy to choose. If the repeater is outside the window, then the indoor option is preferable. It is enough to buy a couple of meters of coaxial wire in addition, and this is enough for the installation of equipment. An indoor antenna is cheaper, equipped with a stand, often instructions allow placing it near the window.
Outdoor options are required where the signal is relatively weak. On the rooftop, the reception is incomparably better, and this fact can be used to enjoy digital broadcasting. Passive antennas for the street did not come across, but if there are any in nature, then it is worth considering that the signal level at the TV input will greatly depend on the length of the cable. Those living on the second floor are more likely to need an active antenna.
Hybrid options allow you to install yourself both in the room and on the roof without sacrificing quality. Well, and the price, of course, will be higher than that of the room.
When choosing your equipment for receiving a signal, make sure that the antenna and broadcast bands match. Check with your digital TV provider for the latter. They produce both varieties that completely cover the channels and selective antennas.
NPP Ost manufactures a product that is attractive to Russians. Delta is an antenna for digital television, but looking for products through Yandex is a bad job. The St. Petersburg manufacturer distributes products through dealers. And everything that the consumer only needs is available.
Moreover, there are any performances on the counter in terms of installation locations, but also the construct shines with variety. It is based on logarithmic and frame elements, but the external form is so amazing that it is recommended to visit the site at least to simply admire this splendor. The wealth of engineering solutions is striking. Unlike foreign products that look the same.
Self-taught people have chosen the simplest method of making devices. Coaxial cable is chosen as the material. Use a television characteristic impedance of 75 ohms. Enough to ensure reliable reception of a single broadcasting frequency. Three multiplexes are available to Muscovites, the spectrum is constantly expanding.
Good luck! Read our reviews, watch digital TV.
Digital terrestrial television is a good budget satellite TV alternative. Its main advantages are the perfect picture and sound quality and the absence of a monthly fee. For reception, you only need a set-top box (receiver) and an antenna for digital television, and an excellent picture is guaranteed with any TV. A flawless image is achieved due to a qualitatively different method of signal transmission than in the case of analog television. The digital signal is not subject to interference and interference and is much less dependent on the distance to the transmitter.
What channels can be received with the DTV antenna?
The first and second channels, which are already available today in Moscow and in many regions for free reception, include 20 federal channels (Channel One (1TV), "Russia-1", "TVC", "NTV", "Channel 5" (St. Petersburg), "Russia-2", "Russia-24", "Russia-Culture", "Karusel", "OTR" (1st multiplex); "REN-TV", "STS", "Domashny "," TV-3 "," SPORT-PLUS "," SPAS "," ZVEZDA "," MIR "," TNT "," MUZ-TV "(2nd multiplex). The broadcasting zone of the third federal multiplex from 10 channels During 2015, the third multiplex was launched, with a total of at least 10 channels, including HD Digital television is already broadcast in more than 80 regions of Russia.
Antenna for digital television - how to choose?
At the place of installation, the antennas are indoor and outdoor, respectively for the house and for the summer cottage. They are also divided into active and passive, depending on the presence of a built-in signal amplifier, powered by the network. If you live near a TV tower, a passive (without an amplifier) indoor antenna is recommended for reception: signal amplification can distort it. At a distance from the TV tower, for example, in a country house or in a country house and there are obstacles (trees, buildings), an external antenna with a built-in or external signal amplifier is required. The main condition when choosing an antenna for digital television should be reliable reception in the UHF range. Attention outdoor antennas can be found in the section Outdoor antennas for digital television
Is it possible to make the antenna work for two TVs?
Two or more TVs can be connected to one antenna for digital television. However, if you use one receiver for reception, then the same channel will be shown on each TV. To watch different channels at the same time, you need to purchase receivers for other TVs.
The delivery department will bring the goods of your choice to any point in Moscow and the Moscow region.
The era of digital signals has arrived. All broadcasting TV companies began to work in a new format. Analog TVs are living out their days. They are still in working order and are available in almost every family.
In order for the old models to successfully finalize their resource, and people can use them when watching digital broadcasting, it is enough to connect the DVB-T set-top box to the TV receiver and catch the TV wave signals with a special antenna.
Any home craftsman is able not to buy an antenna in a store, but to make it with his own hands from available tools for watching digital TV programs at home or in the country. The two most affordable constructs are described in this article.
A bit of theory
Principle of operation of an antenna for digital packet television
Any television signal propagates in space from the emitters of the transmitting television tower to the television antenna by a sinusoidal electromagnetic wave with a high frequency measured in megahertz.
When an electromagnetic wave passes through the surface of the receiving antenna beams, a voltage V is induced in it. Each half-wave of a sinusoid forms a potential difference with its own sign.
Under the influence of the induced voltage applied to the closed receiving circuit of the input signal with resistance R, an electric current flows in the latter. It is amplified and processed by the digital TV circuitry and output to the screen and speakers as picture and sound.
For analog models of TV receivers, an intermediate link works between the antenna and the TV - the DVB-T set-top box, which decodes the digital information of the electromagnetic wave into its usual form.
Vertical and horizontal polarization of digital TV signal
In television broadcasting by state standards, it is customary to emit electromagnetic waves in only two planes:
- horizontally.
In this way, the transmitters direct the emitting signals.
And users just need to rotate the receiving antenna in the desired plane to maximize the removal of the power potential.
Digital Packet TV Antenna Requirements
TV transmitters spread their signal-waves over short distances, limited by the line-of-sight from the top point of the TV tower emitter. Their range rarely exceeds 60 km.
For such distances, it is sufficient to provide a small power of the emitted TV signal. But, the intensity of the electromagnetic wave at the end of the coverage area should form a normal voltage level at the receiving end.
A small potential difference is induced at the antenna, measured in fractions of a volt. It creates currents with small amplitudes. This imposes high technical requirements on the assembly and workmanship of all parts of digital reception devices.
Antenna design should be:
- made accurately, with a good degree of accuracy, excluding the loss of electrical power of the signal;
- directed strictly along the axis of the electromagnetic wave coming from the transmitting center;
- oriented by the type of polarization;
- protected from extraneous interference signals of the same frequency coming from any sources: generators, radio transmitters, electric motors and other similar devices.
How to find out the initial data for calculating the antenna
The main parameter influencing the quality of the received digital signal, as can be seen from the explanatory first figure, is the length of the electromagnetic radiation wave. Symmetrical arms of vibrators of various shapes are created under it, the overall dimensions of the antenna are determined.
The wavelength λ in centimeters can be easily calculated using a simplified formula: λ = 300 / F. It is enough just to find the frequency of the received signal F in megahertz.
We will use the search for GUGL for this and ask him for a list of regional TV communication points for our area.
As an example, a fragment of the data table for the Vitebsk region is shown with a red rectangle highlighting the transmitting center in Ushachi.
Its wave frequency is 626 megahertz, and the type of polarization is horizontal. This data is quite enough.
We carry out the calculation: 300/626 = 0.48 m. This is the length of the electromagnetic wave for the antenna being created.
We divide it in half and we get 24 cm - the required half-wave length.
The maximum value of the tension reaches in the middle of this area - 12 cm. It is also called the amplitude. A whip antenna is made for this size. It is usually expressed by the formula λ / 4, where λ is the length of the electromagnetic wave.
The simplest TV antenna for digital television
It requires a piece of coaxial cable with a characteristic impedance of 75 ohms and an antenna plug. I managed to find a ready-made two-meter piece in the old stock.
From the free end, I cut off the outer shell with an ordinary knife. I take the length with a small margin: when setting up it is always easier to bite off a small piece.
Then I remove the shielding layer from this section of the cable.
The work is done. It remains to insert the plug into the connector on the TV signal set-top box and direct the bare wire of the inner core across the incoming electromagnetic wave, taking into account the horizontal polarization.
The antenna should be placed directly on the windowsill or fixed to the glass, for example, with a piece of tape or tied to the blinds mount. Reflected signals and interference can be shielded with a strip of foil located at a short distance from the central core.
Such a design is done literally in a dozen minutes and does not require special material costs. It's worth trying it. But, it is capable of working in the area of reliable signal reception. My building is shielded by a mountain and a multi-storey building. The transmitting TV tower is located at a distance of 25 km. Under these conditions, the digital electromagnetic wave is reflected many times and poorly received. I had to look for another technical solution.
And for you on the topic of this design, I propose to watch the video of the owner Edokoff "How to make an antenna for digital TV"
Antenna Kharchenko at 626 MHz
To receive analogue TV broadcasting signals of various wave frequency ranges, the design of a zigzag broadband antenna used to work well for me, which does not require complex manufacturing.
I immediately remembered one of their effective varieties - the Kharchenko antenna. I decided to use its design for digital reception. I made the vibrators from a flat copper bus, but it is quite possible to get by with a round wire. This will make it easier to bend and align the ends.
How to determine the dimensions of a specific antenna
Online calculator
Let's use the omniscient Google search. We write in the command line: "Calculation of the Kharchenko antenna" and press Enter.
We choose any site you like and perform an online calculation. I went to the first one that opened. Here's what he calculated for me.
I presented all his data with a picture with the designation of the name of the dimensions of the Kharchenko antenna.
Manufacturing of antenna structure parts
I took the information provided as a basis, but did not exactly maintain all the dimensions. I know from previous practice that the antenna works well in the broadband wavelength range. Therefore, the dimensions of the parts were just slightly overestimated. The half-wave of each harmonic of the sinusoid of the electromagnetic TV signal will fit into the shoulder of each vibrator and will be received by it.
Based on the selected data, I made blanks for the antenna.
Vibrator design features
The connection of the ends of the shank for the figure-eight is created in the center during the bending stage. I soldered them with a soldering iron.
I have it created according to the "Moment" principle, made by hand from old transformers, it has been working for two decades. They even soldered a copper wire 2.5 squares in a thirty-degree frost. Works with transistors and microcircuits without burning them out.
I plan to describe its design in a separate article on the site in the near future for those who also wish to make it with their own hands. Follow the publications, subscribe to notifications.
Connecting the antenna cable to the vibrator
The copper core and braid were simply soldered to the metal of the figure eight from different sides along its center.
The cable was tied to a copper bus, bending it in a loop in the shape of a semi-square vibrator. In this way, the cable and antenna impedances are matched.
Shielding grid design
In fact, Kharchenko's antenna often works fine without shielding the signals, but I decided to show its manufacture. I took a wooden block for the base. I did not paint and saturate with varnish: the structure will be used indoors.
In the back of the block I drilled holes for attaching the screen wires and inserted them, and then jammed them.
The result is a screen for Kharchenko's antenna. In principle, it can be made of a different design: cut out of a piece of frontal armor of a tank or cut out of food foil - it will work in about the same way.
On the reverse side of the bar, I fixed the structure of the vibrator with a cable.
The antenna is ready. It remains to install it on a window to work in vertical polarization.
When a television receiver is located at a great distance from the transmitting generator, its signal strength gradually weakens. It can be increased by special electronic devices - amplifiers.
You just need to clearly see the difference between the signals received by the antenna, which can be:
- just weakened;
- contain high-frequency interference that distorts the shape of a digital sinusoid to the shape of some kind of "karyabola".
In both cases, the amplifier will do its part and raise the power. Moreover, the TV will clearly perceive and display the weakened signal, and with the reinforced "karyabola" there will be playback problems.
To eliminate such interference waves are designed:
- h / h filters;
- screens.
They need to be measured with an oscilloscope, and the ways of using different designs should be analyzed on a case-by-case basis. The antenna is not to blame here.
