The article discusses connection diagrams for street (with built-in amplification board) and passive ones with external ones.
Attention! A TV signal amplifier is not a filter; as a result, it will amplify both the useful signal and the interference.
From the above it follows that it will not help if:
- The signal power is greater than needed for ;
- The antenna, in addition to the useful signal, also catches a strong interfering signal, it will increase sharply after ;
- The antenna signal is critically low (there is nothing to amplify).
To connect equipment according to these diagrams we use:
- Outdoor passive UHF antenna. (gain is usually from 6 to 18 dB)
- (we recommend using it, especially when installing the antenna on a mast)
- for two, three or more TVs (operating frequency from 5 to 1000 MHz, losses from 3.2 to 10.0 dB.)
- TV with DVB-T2 tuner or .
- F connectors by number of connections.
- (gain from 18 to 34 dB.)
- DG 113
So the first and most simple circuit connecting one TV.
To connect two devices we use .
From practice! According to this scheme, a country mini-hotel with 12 rooms was connected. The following equipment was used for connection: Outdoor antenna “Vector-806” gain 16 dB; Amplifier “TERRA HA 126” 34 dB, 117 dBmV; Dividers 1x2 1 pc. 1x6 2 pcs. Lightning protection 1 pc. F connectors 22 pcs. Cable DG 113.
Someone will say why not do the wiring with help and save on?
It is possible, but in the future if you want to connect, then during wiring you will need to replace them with multiswitches. And when used, you will have to change almost all the wiring, or make a new one. Connection diagrams for digital plus satellite television.
- A divider is a device that divides the signal equally among all outputs.
- A coupler (TAP) is a device that provides a small part of the signal as a tap, and passes the majority of the signal further along the cable (depending on the rating).
If you have, then you must additionally have a power supply with a separator. The connection diagram for two or three TVs is shown below. In general, the scheme works, but there are disadvantages:
- Thunderstorms can burn out the amplification board. (grounding the antenna in most cases does not help);
- The power supply included in the kit is not stabilized. It often burns out due to voltage surges.
- When wiring to several devices, the signal drops.
An antenna amplifier for a TV is widely used in the CIS. It is the optimal solution for improving the quality of the TV signal. The antenna's own gain does not play a significant role, but its antenna amplifier seriously affects the picture quality.
The best amplifiers that have proven themselves over the years of operation are considered to be SWA-7, 14, 17, 107, 109, 2000. The SWA-2000 is a newer antenna amplifier that has two additional transistors. The amplifier contains two transistors VT1 and VT2, which are connected in accordance with the circuit to the OE. The signal is collected at the collector in transistor VT2 and is fed through capacitor C9 to the cable. The additional transistors VT3 and VT4 are located in active circuits that provide base bias voltage in transistors VT1 and VT2.
Despite the fact that digital television is being actively introduced, there will always be a demand for antennas with active amplification, since the signal to the television tuner is supplied using antennas with a decimeter range.
So, to improve the television signal, they use an antenna amplifier. The best gain is achieved when the antenna amplifier is installed not next to the television input, but in close proximity to the antenna. To reduce attenuation, it is better to use modern coaxial cables. The amplifier is powered using a coaxial cable. The voltage rating of the power supply in the antenna amplifier is most often 12 V, and the cable attenuation value is 0.1 - 0.5 decibels per m, if we take different television channels.
In rural areas, when television centers are located at great distances, they use amplifiers with a gain of more than 100 dB. If the amplifier was selected incorrectly, or the feeder and antenna are not properly matched, then due to the excitation of the amplifier, the TV screen will display noise and snow.
Although an antenna amplifier for a TV can be purchased at almost any corner, most of them use a standard circuit. That is, they are two-stage aperiodic amplifiers having bipolar high-frequency transistors connected in accordance with the OE circuit. Let's take a closer look at these models: SWA-36 and SWA-49
The SWA-36 amplifier contains broadband amplification stages with transistors VT1 and VT2. The value of the antenna signal, through the matching transformer and capacitor C1, is supplied to the base in transistor VT1, which is included in the circuit with the OE. The operating point in the transistor is determined by the bias voltage, which is determined using resistor R1. At the same time, due to the action of negative feedback(OOS) characteristic in the first stage becomes linear, the position of the operating point stabilizes, however, the gain value decreases.
No frequency correction is applied to the first stage. The second stage is also carried out using a transistor in a circuit with OE and OOS, due to the passage of voltage through resistors R2 and R3. However, there is also a current OOS, through resistor R4, which the emitter circuit has. It stabilizes transistor VT2. To avoid large gain losses, resistor R4 is tongued using capacitor SZ, which has a relatively low capacitance (10 pF).
The result of this is that the lower frequencies in the range of capacitance on the SZ capacitor will be significant and the AC feedback leads to a decrease in gain, due to which the frequency response of the amplifier is corrected. The SWA-36 amplifier has disadvantages, among them the passive loss that the output circuit has.
It implements better isolation of power circuits due to filters L1C6, R5C4 and increased gain thanks to capacitors C5 and C7.
Have you noticed that even if you have a modern and expensive TV, unfortunately, you can only dream of high-quality and stable reception of television channels. With the opening of new channels, more stringent competitive conditions are created due to the use of close frequencies, especially in the decimeter range (DVB-T2). What can be done to improve the reception of TV channels? There are several ways to solve this problem: you can purchase another antenna, an order of magnitude better than the existing one, replace the amplifier with a more efficient one, or use satellite system from any television provider. I decided in favor of replacing the TV antenna amplifier. Poor and weak signal reception is influenced by many factors. Dense urban areas with multi-storey buildings, terrain features along the signal path, a huge distance to the transmitting tower, and often the transmitter itself from the television center is quite weak. All these factors directly affect the signal quality.
In order to significantly improve the quality of reception, and once and for all forget about watching your favorite programs in poor quality, I want to offer a TV antenna signal amplifier that I have tested and tested. Over quite a long period of operation, it has proven itself to be the best, and has made it possible to improve the quality of reception by several times.
There is nothing complicated in making an amplifier; you don’t need scarce and expensive parts to assemble it, and there won’t be any problems in using it, since it easily gets along with all TV receivers.
About the power supply for TV amplifier
The power comes from 12V, which is quite convenient, since it can be powered from the uninterruptible power supply of the TV itself, or from any other suitable source. The amplifier's power supply must have high voltage levels in stabilization and filtering, and in order not to degrade the converted high-frequency signal, and the optimal cable length should be in the region of twenty, thirty meters; a longer cable may affect the quality of reception. The cable used is a regular radio frequency one, with a characteristic impedance in the region of 75-80 Ohms, type RK-75.
The diagram shows the capacitance ratings of all disk capacitors in picofarads, with the exception of C5. Choke L1 type D-0.6, or a similar one with an inductance of 120...200 μH, acts as a cut-off filter. Antenna in in this case the usual UHF (DVB-T2) is used.
All elements of the amplifier are assembled on a PCB board intended for circuits; its size should be 20 by 10 mm. Soldering of pins to isolated sectors on the board occurs. The lower foil PCB substrate should also be connected to the common wire, like the rest of the remaining sections of the circuit board on the working main surface of the board. The length of the leads of all radio elements on the board is also reduced to the minimum possible, and the board itself is placed in a shielded case. It is made from scrap materials, or from the same PCB. According to the size of the board, blanks for the case are cut out of textolite and assembled by soldering from the inside. You should get a closed box, with a removable top cover, the body of which must be connected to a common wire. It is better not to use connectors in the circuit, but to use only soldering for greater reliability. All wiring is routed through a hole prepared in the housing. These shielding actions are mandatory; this allows you to get rid of interference and interference created by different devices, which operate at high purity. It is best to place the amplifier as close as possible to the television antenna, this will maximize the signal amplification and minimize interference.
That's all. If you have comments or suggestions regarding this article, please write to the site administrator.
The receiving television antenna receives from the television center electromagnetic radiation, which induces currents flowing into the coaxial cable on its conductive elements. Depending on the design of the antenna with directional properties, it is possible to obtain a signal of different strengths. In this regard, the concept of the directional coefficient of a TV antenna is introduced, which shows how many times the signal at its output exceeds the signal from a half-wave vibrator if it is placed in the same place in space.
TV antenna with amplifier
The actual power gain taking into account losses will be:
K p = KND∙η,
where η – coefficient useful action, taking into account losses.
Application
The level of the electrical signal coming through the TV antenna input does not always suit the user. To improve the performance of the receiver, you need a signal amplifier located nearby. It is especially required outside the city, where there is no cable network.
At the dacha, signal reception conditions are worse than in the city. It is affected by interference and distance from the television center. Despite the fact that a TV amplifier slightly distorts the input signal, experts recommend using it.
In high-rise buildings, the signal comes from top to bottom and weakens significantly at the end. If it has low power, it is largely attenuated to the connection socket. In the cable, the signal is lost by 0.2-0.7 dB/m.
Amplifier selection
The antenna amplifier is connected as close as possible to the TV antenna. Placing it near the receiver will increase the noise along with the transmitted signal, and the image will be worse. The power supply can be placed near the amplifier, or separately.
Home antenna made together with an amplifier
The parameters that determine the correct choice of amplifier are as follows:
- distance from the television center;
- required frequency range;
- the type of antenna for which the signal is amplified.
The maximum distance to the signal transmission source should not exceed 150 km. At a distance of less than 10 km, an amplifier is usually not installed, since the signal level is quite high. To obtain a normal signal, it is advisable to choose a good antenna. How to make a TV antenna with your own hands from wire.
The gain should not be too high, otherwise significant noise may appear from self-excitation. Many models produced have different characteristics. Here it is worth contacting a specialist who knows how to improve reception and will help you choose the necessary device. Installing a broadband amplifier on the antenna makes it possible to cover the entire television broadcast range.
In Russia, antennas with amplifiers made in Poland (ANPREL) are common. Their own gain is small, and the parameters are mainly determined by the additional amplifier. It has the following disadvantages: self-excitation, high level generated noise, overload from powerful VHF signals, damage from lightning discharges, passive output losses.
In most TV amplifiers, they operate according to a standard two-stage circuit based on bipolar transistors high frequency with a common emitter.
Amplifiers on two stages: SWA-36 (a) and SWA-49 (b)
The amplifier stage captures the wideband band. The input signal is fed to the base of the transistor (T1) through a capacitor (C1). The necessary linear characteristic in it is created by applying a bias voltage through a resistor (R1). But at the same time the gain decreases. The next stage is created according to a similar circuit with stabilization of the transistor (T2) in the emitter circuit by feedback through a resistor (R4).
It is not recommended to significantly increase the Kp of the antenna amplifier, since it creates its own noise, which increases along with the input signal. It is not difficult to make the circuit yourself.
You can improve the circuit using the SWA-49 model. This is ensured by using filters L1C6, R5C4 and increasing K p by adding capacitors (C5) and (C7).
Other ANPREL models differ slightly from the above circuits in the presence of frequency correction circuits at the output and the organization of feedback, on which the gain value depends. If it is close to the stability threshold, there is a high probability of self-excitation of the amplifier.
TVs themselves have significant signal amplification. The larger it is, the higher the intrinsic noise becomes. Therefore, it is necessary to understand that reception capabilities may be influenced to a greater extent by their own noise interference than by a weak signal at the input. The signal must be at least 20 times higher than the noise voltage. Closer to this value the image becomes poor and fine details can no longer be distinguished.
The transistor of the first stage has the maximum influence on the self-noise level of the antenna amplifier. Amplifiers should be selected correctly based on noise level, which should not exceed 2 dB. It may not be indicated in the instructions, but it can be found on the Internet or company catalogs.
The gain is needed mainly to compensate for losses in the cable. They are especially large on channels 21-60 and amount to 0.25-0.37 dB/m. An industrial splitter adds losses, which are indicated on the housing. It should be taken into account that the indicated signal attenuation value (usually 3.5 dB) may differ at different wavelength ranges. This may be the maximum or average value. In any case, you need to take a factory product, not a homemade one. Then 12-14 dB should be added to the total attenuation so that weak signals are captured.
What does an antenna splitter look like?
Antenna signal power
There may be several reasons for the weakening of the signal from a satellite dish:
- Failure to adjust the antenna position. Sometimes it is enough to turn it just a little. If the fastening screws are loose, they should be tightened.
- The appearance of an unexpected obstacle that must be removed or the antenna location changed.
- Cable failure. The best option is its replacement. It is important to make a good fastening so that it does not dangle from the wind.
- Excessive cable length. A better quality one is selected or an amplifier is installed.
- If everything is in order, but the signal is not enough, you should purchase an antenna with a larger diameter.
A signal amplifier for a satellite TV antenna is installed between it and the receiver. With a cable length of 40 m, the signal attenuation will be 40x0.37 = 14.8 dB, and with a splitter - 18.3 dB. The receiver input level is 48-75 dB. If it is close to the lower limit, an amplifier will be needed. If we take a 20dB IF model, it has a gain of 20 dB, which is sufficient to compensate for attenuation.
The frequency range of satellite antennas is 950-2400 MHz, for which this amplifier is suitable (Fig. below a). You can also purchase the Gecen A05-20 model with similar parameters (Fig. b).
Satellite antennas (a) and amplifier for them (b)
You should purchase amplifiers designed for the frequency range of a television antenna. Upper limit for terrestrial television is 950 MHz, and for satellite – 2400 MHz.
DIY amplifier
Even a beginner can assemble a simple device on a microcircuit with his own hands. It does not create much interference, consumes virtually no energy and operates at frequencies up to 900 MHz.
Amplifier chip that you can assemble yourself
The basis of the circuit is a low-noise low-voltage amplifier microcircuit (power supply 2.7-5.5 V). The circuit consumes only 3 mA current. Voltage is supplied to input (1). Offset in work area creates a resistor (R1) connected to input (2). The input signal from the antenna arrives at pin (6), and the amplified signal is removed from pin (3) and goes to the receiver. Capacitors (C1-C3) are added to the microcircuit, separating alternating signals from the direct component of the power source voltage. If assembled correctly, the circuit does not need to be configured.
You can also make devices with your own hands according to the previously given schemes, for example, such as SWA amplifiers.
How to improve the signal. Video
The video below will tell you how to improve the signal of a television antenna.
It is better to purchase factory-made antennas and TV amplifiers, since they are made according to calculations. If you make the devices yourself, their quality will be an order of magnitude lower. For TV reception in the country you need to have devices High Quality due to the distance from the television center and the presence of a large amount of interference.
After working at your site during the day, in the evening you want to relax and watch an interesting film or evening concert on television.
But often, especially for summer cottages remote from large cities, the pleasure of viewing is sharply reduced due to the poor quality of television signal reception. In this case, more attention needs to be paid to the television antenna. Let's figure out when you might need an amplifier for a TV antenna in the country and how to choose it.
Currently, satellite antennas or terrestrial television antennas are used to receive television signals in suburban areas.
Satellite dishes
A good solution to the problem of obtaining a high-quality signal is to use a satellite dish. Satellite television channels broadcast television programs from satellites and do not depend on terrestrial television transmission centers. Modern satellite television covers the entire globe. You only need to purchase and install a satellite dish with the appropriate equipment.
Advantages of satellite dishes:
- accept a large number of TV channels;
- reception does not depend on the terrain;
- have a low weight structure;
- do not require special maintenance.
A typical receiving satellite antenna consists of a reflector, which is a so-called dish (paraboloid of rotation) and an irradiator (receiver) installed at its focus. Offset antennas are more often used, in which the focus is located below the geometric center of the antenna, which increases its stability and sensitivity. The received high-frequency signal is amplified and converted, and then transmitted through cables for further conversion into a television signal.
A satellite antenna can have a diameter from 0.55 to 5 m. Depending on this diameter, the sensitivity of the antenna also changes.
To receive programs from various satellites, sets of satellite receiving systems are available. For example, satellite dish kits are sold that allow you to connect to the most popular television satellites “Tricolor” or “NTV-Plus”.
Installing and configuring a satellite dish is quite a complex job, so in most cases it is better to contact a specialized company to install a satellite dish, although this is an expensive undertaking. For example, a set satellite television“Tricolor TV” with the GS 6301 receiver costs 7,190 rubles, and with installation - 9,700 rubles.
Terrestrial television antennas
More common for country houses and cottages are terrestrial television antennas.
Terrestrial television antennas can be indoor or outdoor.
Indoor
can be used if the cottage is located close to the repeater and the level of the received signal is quite high. When receiving a signal with an indoor antenna, there are a number of features. These features include:
- weakening of the signal inside the building;
- multiple reflections of this signal from various objects.
As a result of reflections at different points in the room, the signal has different magnitudes. Therefore, when using an indoor antenna, it is necessary to determine the most effective location for its installation.
Indoor antennas come in frame and rod types. The former operate in the decimeter range, and the latter in the meter range.
External
If you are far away from the repeater, you must use an external antenna.
Main characteristics of antennas:
- operating frequency range;
- antenna radiation pattern;
- gain;
- input resistance.
The operating frequency range of the antenna determines the range in which the antenna provides all specified characteristics. The radiation pattern determines the directional actions of the antenna and is measured by the width of the main lobe at some given level. Gain shows how much a given antenna amplifies the signal compared to a simple antenna. Gain is measured in decibels.
Antenna input impedance varies by design and affects matching with the rest of the circuit. If this impedance differs from the standard characteristic impedance of 75 Ohms, then a special high-frequency transformer is used to match the antenna.
External antennas come in the following types:
- half-wave vibrator;
- wave channel;
- log-periodic;
- common mode antenna array.
Half-wave vibrator represents the simplest antenna with a gain of 1 dB and a figure-of-eight pattern in the plane of the antenna.
Antenna - wave channel consists of an active vibrator, reflector and large number directors, which form a narrow antenna radiation pattern.
To cover a wide decimeter range it is used log periodic antenna, consisting of a large number of vibrators of different lengths. A wide operating band in such an antenna is ensured by the fact that at each frequency its own vibrators are excited, ensuring reception of a given frequency. Other vibrators do not affect the operation of the antenna at this frequency.
Example common mode antenna array The so-called “Polish” antennas of the ASP-8 type, which were very common in dachas back in the 90s and continue to be sold today, can serve. Such an antenna is a system of omnidirectional antennas spaced apart in space. Due to the phase difference, a narrowly directional diagram is formed. The antenna covers the range of television channels from No. 6 to No. 69, has a gain of 14 dB and an input impedance of 75 Ohms.
Combined
In order to cover the meter and decimeter wavelength ranges, combined antennas are also used. For example, in antennas such as “Locus” or “Delta” a vibrator is used for the meter wavelength range, and a log-periodic antenna for the decimeter wavelength range.
Factors affecting television signal deterioration
Outside the city, even a very expensive TV sometimes produces poor image quality. The reasons for poor image quality may be the following:
- long distance of the TV from the broadcaster;
- poor quality connecting cable;
- presence of artificial or natural interference.
When the signal is weak, noise appears on the TV screen that is usually invisible. If they look like “snow,” then this is the noise of the television amplifier itself. In order to increase the signal in this case, it is necessary to adjust the orientation of the antenna or increase its installation height. If these measures do not help, then if you are far away from the transmitter, you can try using an antenna signal amplifier.
The signal at the TV input may be weakened due to poor quality connecting cable. For example, when connecting cable sections by twisting. In any case, connections can only be made by soldering. And it is best that the cable is intact from the antenna to the entrance to the television receiver. If the cable has worked for more than 20 years, it is recommended to replace it.
If stripes, loss of synchronization, or shaking images appear on the TV screen, then, apparently, interference is passing through to the TV. This interference may be due to the operation of household electrical appliances and the operation of external sources, such as radio stations, cellular transmitters, electric train sparking and the like. If household appliances can be turned off, then you can tune out external sources by using antennas with a narrow radiation pattern.
Using an antenna amplifier
If the TV is located at a great distance from the TV broadcaster, the weak TV signal can be increased using an antenna amplifier.
Most commercially available television antennas are active. This means that they include an antenna amplifier.
An example is a Polish-made antenna of the ASP-8 type. This antenna offers several amplifier options with different gains. The type of amplifier is selected depending on the distance between the broadcaster and the television antenna.
The gain of the amplifier in the UHF range (21-60 channels) is 30-40 dB, in the meter range (1-12 channels) it is about 10 dB, and the noise figure of the amplifier is 3 dB. Power is supplied from a separate stabilized source of 12 V with a current consumption of 65 mA.
When choosing an antenna amplifier, you need to consider the following parameters:
- gain in decibels (dB);
- noise figure in dB;
- supply voltage;
- current consumption.
To reduce the influence of loss noise in the supply cable, the amplifier is mounted directly on the antenna. Power is supplied to the amplifier transistor through a coaxial cable. The price of such an amplifier is only 120 rubles.
Setting up the amplifier is done by selecting the appropriate type of amplifier. At the same time, sellers usually give a couple of weeks to check the amplifier in the antenna. During this time, it is allowed to replace the purchased amplifier with another. Experience shows that sometimes when tuning it is necessary to slightly change the gain by adjusting the supply voltage. But this must be done carefully so as not to damage the amplification device.
DIY antenna amplifier
If you wish, you can assemble the antenna amplifier yourself. For example, a broadband amplifier circuit for the range 30-850 MHz using imported S790T transistors is proposed. The amplifier is a two-stage resistor-based amplifier. Each stage provides a gain of 10 dB.
The amplifier is powered from a source direct current with a voltage of 9−12 V. The circuit is designed as printed circuit board. It can be installed near the TV.
Antenna for digital television reception
In accordance with the Federal program, the country is transitioning to digital television. Recently, such television masts have been installed in different parts of the country. For example, in the city of Zaraysk, Moscow region, a digital broadcasting mast was installed, with the help of which free transmission of RTRS-1 channel packages is carried out on channel 59 with a frequency of 778 MHz. The package includes 10 of the most famous channels.
In order to receive digital television at the dacha there is no need to upgrade it to an antenna operating in the UHF wavelength range. If you have a TV with a built-in DTV-T2 tuner, no changes need to be made. In other cases, the upgrade concerns the TV, to which you need to connect the DTV-T2 tuner set-top box.
- When receiving television programs in a country house, various interference often occurs and the image deteriorates.
- To receive high-quality TV programs in your dacha, you must have good antenna— satellite dish or high-quality outdoor antenna.
- To increase the value of the received signal, it is necessary to use antenna amplifiers, and to tune out interference, an antenna with a narrow radiation pattern.
- Outdoor UHF antennas are quite suitable for receiving digital television, but for an old TV you need to connect a DTV-T2 tuner set-top box.
The following video will help you decide on the choice of antenna amplifier: