Homemade antenna for tsv. Instructions for making a television antenna for a DIY

It was always difficult to get high-quality antennas - the Soviet industry practically did not produce them, so people themselves made them from improvised means. Today, the situation has not changed much - in stores you can find only light aluminum Chinese crafts that do not show good results and rarely live more than a year. What to do if you like to watch TV, but there is no high-quality reception? The answer is simple -In the presence of free time and a pair of skillful hands, everyone can handle this.

More recently, analogue television was operating in Russia, but now almost the entire country has switched to digital broadcasting. Its main difference is that it operates in the decimeter range.

Create a homemade antenna for digital range possible at home

This was done for reasons of economy and safety - maintenance of transmitting antenna-feeder stations is practically not required, their maintenance is minimized, the damage from contact with powerful transmitters for the masters is minimal. But such stations have one serious drawback - low power. And if in a big city the signal can often be caught even on a piece of copper wire, then far from the transmitter, reception can be difficult. If you live outside the city, in remote areas or villages, you will have to collect your own antenna and put it out on the street to catch the desired signal.

Attention:a signal problem can occur even in the city center. Decimeter waves are practically not suppressed by other sources, but are reflected from thick reinforced concrete walls. In modern high-rise buildings, there are many places where they completely fade out before reaching the TV receiver.

It is also worth noting that DVB-T2 (the new television standard) offers a fairly constant, but weak signal. At a noise level one and a half to two units above normal, the television reproduces the ether quite clearly, but as soon as the noise exceeds 2 dB, the signal completely disappears. Digital television is not sensitive to electromagnetic interference - it does not interfere with a working refrigerator or microwave. But if there is a mismatch in the system anywhere, then the picture stops or crumbles. Qualitywill solve this problem but in some cases it will have to be led out onto the street or on the roof.

Basic Antenna Requirements

Television standards in force in the USSR are not suitable for modern realities — today, the coefficients of protective and directed action practically do not affect signals. The air in the cities is clogged and contains a lot of dirt, so you should not pay attention to these coefficients. You are guaranteed to receive interference on any antennas, so there is no need to achieve a reduction in the short-circuit efficiency and low-voltage gain. It is better to improve the antenna gain so that it receives a large range of ether and emits the desired stream, rather than focusing on a specific signal. The processor of the set-top box or TV itself will figure out the necessary signals and create a normal picture.

Classical Polish antenna with amplifier

So, Experienced engineers recommend building band antennas. They must be correctly calculated, receiving signals in the classical way, and not due to engineering “optimizations” and traps. The ideal option - the device is fully consistent with theoretical calculations and geometry. Also, the built antenna must be consistent with the cable on the operating ranges without the use of matching devices. In this case, the frequency response is best created smooth and even, since phase distortions appear during a dip or jump in the amplitude-frequency characteristic.

Attention:analog antennas with ferrite CSSs that provide full-fledged reception of the old signal practically do not work with DVB. It is the “digital” antenna that needs to be built.

In this article we will analyze the modern types of antennas that work with the new digital broadcasting.

Antenna Types

What are the antennas for digital TV do-it-yourself can I assemble at home? There are three common options:

1. All-wave, or as it is called ham, is frequency-independent. It is assembled very quickly, does not require high knowledge or specialized tools. It is well suited for the private sector, towns, country cooperatives - where the air is not littered with garbage, but also not far from the transmitter.
2. Log-periodic range. It has a simple design, it receives a signal well at short and medium distances from the transmitter. It can be used as a remote if the transmitter is located far away, or as a home wall antenna.
3. Z-antenna and its variations. Many radio amateurs are familiar with meter “zeshkas” - they are quite large and require a lot of effort to build. But in the decimeter range, they are quite compact and do their job well.

Construction Nuances

If you want to build a high-quality antenna, then you must master the art of soldering. You can not twist the contacts and guides - during operation, they are oxidized, the signal is lost, the picture quality deteriorates. Therefore, all connections are soldered.

Such connections are unacceptable - be sure to solder them

You also need to deal with points of zero potential, in which currents occur even in the absence of voltage. Experts recommend making them from a single piece of metal without using welding at all. Even well-cooked pieces can make noise at the boundary values, while a solid strip “pulls” the signal.

Also when creatinghomemade antenna for digital tv you need to deal with cable soldering. Today, copper is practically not used for braiding, since it is expensive and quickly oxidizes. The modern braid is made of steel, which is not afraid of corrosion, but it is very poorly soldered. It must not be overheated or pinched. To connect, use 36-40 watt soldering irons, flux and light solders. Dip the winding well into the flux and apply solder - it is perfectly taken with this method of application.

All-wave antenna

The all-wave antenna has a fairly simple design. It consists of triangles, copper wire and wooden battens. You can study the detailed design in the picture - it does not represent something supernatural.

The thickness of the wire can be any, the distance between adjacent wires is 25-30 mm, the distance between the plates is not more than 10 mm. Improving the design can be due to the rejection of the plates and the use of PCB. He needs to be given the appropriate shape or just remove the copper foil in the shape of a triangle.

The remaining proportions are standard - the height of the device must match the width, the plates diverge at right angles. Zero potential is on the extreme linehome antenna for tv , just at the intersection of the cable with the vertical guide. To avoid quality losses, the cable must be pulled to it with a cable tie - this is enough for coordination. Such an antenna, hung out on the street or aimed at the window, takes almost the entire frequency range, but has a small dip, so you need to set the correct angle when fixing the antenna.

By the way, this design can be upgraded using conventional aluminum cans of beer and cola. The principle of its action is as follows: with an increase in the magnitude of the shoulders, the working strip expands, although the remaining indicators remain within the original limits. The Nadenenko dipole, often used in military developments, works on the same principle. Aluminum cans are ideal in shape and size, creating the shoulders of the vibrator in the decimeter range.

Dual-Bank TV Antenna

You can create a simple can antenna simply by soldering two cans to the cable. ThisdIY indoor TV antenna Suitable for viewing channels at a small to medium distance from the transmitters. There is no need to coordinate anything in this scheme, especially if the cable length is less than 2 meters.

You can complicate the design by collecting from eight cans a full-fledged array and using an amplifier from a conventional Polish antenna. This design is great for hanging on the street in areas remote from the transmitter. To amplify the signal, a metal mesh can be placed behind the structure.

Z antenna

There are complex designs of Z-antennas with multiple loops, but in most cases they are not needed. It is easy to assemble a structure of ordinary copper wire 3 mm thick. If you do not have it, then just buy a single-core copper wire 3 mm long, 120 mm long - this is quite enough for you to work. This design consists of two segments. We bend the wire according to this scheme:

1. The starting section is 14 centimeters long. Its edge is bent into a loop to connect with the latter (loop 1 cm, the total length of the first piece - 13 cm).
2. The second piece bends at 90 degrees (it is better to bend with pliers to comply with the corners). Its length is 14 cm.
3. The third piece bends at 90 degrees parallel to the first, length 14 cm.
4. The fourth and fifth pieces are 13 cm each, the bend does not reach the loop by 2 cm.
5. The sixth and seventh piece of 14 cm, bend at 90 degrees.
6. Eighth - returns to the loop, the length of 14, 1 cm goes to a new loop.

Next, you need to clean the two loops well and solder them. The opposite corner is also cleared. The cable contacts are soldered to them - to one central, to the second - braid. There is no difference to which contact to solder. It is advisable to insulate soldered areas, for this you can use sealants or hot-melt adhesive. The ends of the cable are soldered to the plug and also insulated with cambric.

You can assemble such an antenna in half an hour

To avoid displacement of the segments, the edges can be strengthened. To do this, take a regular plastic cap from a five-liter bottle, cut 4 slots in it so that the wire is recessed to the base. Cut the fifth hole under the cable. Then put the antenna in the lid (after checking the quality and reliability of the soldering), and fill it with hot glue. The resulting design will be almost eternal - it is able to receive a stable signal at a distance of 10 km from the source.

So you already knowwhat can be used instead of the antenna for the TV. In fact, the designs are much larger than those that we described, but even these will be quite enough for you. If you live far from the signal source, then you will need amplifying antennas - you can get by with the classic “polka” with amplification. Well, if everything is bad with the ether, then use satellites.

“Different things” happen in life. Sometimes it happens that you are left even without a TV. Moreover, the TV itself is, but there is no antenna for it. How to receive a signal in this case? In fact, a completely effective receiver can be easily built on its own. All that is needed for this is a piece of a suitable cable.

You can create a modern DVB-T2 television antenna yourself from improvised materials. To do this, you will need to find a 20 cm long television coaxial cable, an F type connector, and an RF connector. Of course, you will need some tools, among which are required to be a tape measure, wire cutters, a knife and pliers.

Before you begin to make such an antenna, you should find out the frequency of broadcasting in your village. In most cases, such information is contained on the official website of the country's broadcasting company. Broadcast frequency will be indicated in MHz. It is needed in order to determine the minimum antenna length. Most often, the receiver should be around 10 cm. To do this, 7,500 should be divided by the broadcasting frequency in your region (the resulting figure will be the required length).

Now we pass directly to the manufacturing process. We take our coaxial cable 20 cm long and remove 3 cm of insulation from one of its sides for the connector F. It is necessary to cut through the cable to the central copper core. After that, you can wind the connector, while the copper tail should not go beyond it by more than 1 cm. Now we wind the high-frequency wire on F, which will connect to the plug.

Stepping back from the connector 3-4 centimeters, we retreat a few more centimeters (as much as it turned out when calculating the length depending on the broadcast frequency) and cut off the rest, the edge is cleaned from insulation. The antenna itself bends at an angle of 90 degrees for better signal reception.

Video

In the past, the site had a lot of other interesting and useful information on how to do something with your own hands. Here, for example, is a small guide on what happens in one way or another in life.

Despite the rapid development of satellite and cable tv, broadcasting is still relevant, for example, for seasonal locations. It is not necessary to buy a finished product for this purpose, a home decimeter (UHF) antenna can be assembled by yourself. Before proceeding to the consideration of designs, we will briefly explain why this particular range of television signal is chosen.

Why exactly UHF?

There are two good reasons to opt for designs of this type:

1. The thing is that most channels are broadcast in this range, because the design of repeaters is simplified, and this makes it possible to install a larger number of maintenance-free low-power transmitters and thereby expand the coverage area.
2. For broadcasting “numbers” this range is selected.

Indoor antenna for TV "Rhombus"

This simple but at the same time reliable design was one of the most common in the heyday of broadcasting.

Fig. 1. The simplest home-made Z-antenna, known under the names: “Rhombus”, “Square” and “People’s Zigzag”

As can be seen from the sketch (B Fig. 1), the device is a simplified version of the classic zigzag (Z-design). To increase sensitivity, it is recommended to equip it with capacitive inserts (“1” and “2”), as well as a reflector (“A” in Fig. 1). If the signal level is quite acceptable, this is not necessary.

As the material, you can use aluminum, copper, as well as brass tubes or strips 10-15 mm wide. If you plan to install the structure on the street, then it is better to abandon aluminum, since it is susceptible to corrosion. Capacitive inserts are made of foil, sheet metal or metal mesh. After installation, they are soldered along the contour.

The cable is laid as shown in the figure, namely: it did not have sharp bends and did not leave the limits of the side insert.

Decimeter antenna with amplifier

In places where a powerful relay tower is not located in relative proximity, you can raise the signal level to an acceptable value using an amplifier. Below is presented circuit diagram A device that can be used with almost any antenna.

Fig. 2. The scheme of the antenna amplifier for the DMV range

The list of elements:

• Resistors: R1 - 150 kOhm; R2 - 1 kΩ; R3 - 680 ohms; R4 - 75 kOhm.
• Capacitors: C1 - 3.3 pF; C2 - 15 pF; C3 - 6800 pF; C4, C5, C6 - 100 pF.
• Transistors: VT1, VT2 - GT311D (can be replaced by: KT3101, KT3115 and KT3132).

Inductance: L1 - is a frameless coil with a diameter of 4 mm, wound with a copper wire Ø 0.8 mm (it is necessary to make 2.5 turns); L2 and L3 are high frequency chokes of 25 μH and 100 μH, respectively.

If the circuit is assembled correctly, we will get an amplifier with the following characteristics:

• bandwidth from 470 to 790 MHz;
• gains and noise - 30 and 3 dB, respectively;
• the value of the output and input resistance of the device corresponds to the cable RG6 - 75 Ohms;
• the device consumes about 12-14 mA.

Let's pay attention to the method of power supply, it is carried out directly by cable.

This amplifier can work with the simplest designs made from improvised means.

Beer can indoor antenna

Despite the unusual design, it is quite functional, since it is a classic dipole, especially since the dimensions of a standard can are great for the shoulders of a decimeter range vibrator. If the device is installed in a room, then in this case it is not even necessary to coordinate with the cable, provided that it will not be longer than two meters.

Designations:

• A - two cans with a volume of 500 mg (if you take tin, not aluminum, you can solder the cable, and not use self-tapping screws).
• B - attachment points of the cable shielding braid.
• C is the central core.
• D - place of fastening of the central core
• E - cable coming from the TV.

The shoulders of this exotic dipole must be secured to a holder made of any insulating material. As such, you can use improvised things, for example, a plastic hanger for clothes, the crossbar of a mop or a piece of a wooden bar of appropriate sizes. The distance between the shoulders is from 1 to 8 cm (selected empirically).

The main advantages of the design are quick production (10 - 20 minutes) and quite acceptable quality of the “picture”, provided that the signal strength is sufficient.

Making a copper wire antenna

There is a design much simpler than the previous version, for which only a piece of copper wire is required. This is a narrow loop loop antenna. Such a solution has undoubted advantages, since in addition to its main purpose, the device plays the role of a selective filter that reduces interference, which allows you to confidently receive a signal.

Fig. 4. Simple loopback UHF antenna for digital TV reception

For this design, you need to calculate the length of the loop, to do this, you need to find out the frequency of the "numbers" for your region. For example, in St. Petersburg, it is broadcast at 586 and 666 MHz. The calculation formula will be as follows: L R \u003d 300 / f, where L R is the loop length (the result is presented in meters) and f is the average frequency range, for Peter this value will be 626 (the sum of 586 and 666 divided by 2). Now we calculate L R, 300/626 \u003d 0.48, which means that the loop length should be 48 centimeters.

If you take a thick RG-6 cable with braided foil, you can use it instead of copper wire to make a loop.

Now we will tell how the construction is going to:

• A piece of copper wire (or RG6 cable) with a length equal to L R is measured and cut.
• A loop of a suitable diameter is folded, after which a cable going to the receiver is soldered to its ends. If RG6 is used instead of copper wire, then the insulation is first removed from its ends, by about 1-1.5 cm (the central core does not need to be cleaned, it is not involved in the process).
• The hinge is mounted on a stand.
• F connector (plug) is screwed onto the cable to the receiver.

Note, despite the simplicity of the design, it is most effective for receiving "numbers", provided that the calculations are carried out correctly.

DIY indoor antenna MV and DMV

If, in addition to the UHF, there is a desire to take MB, you can assemble a simple multi-wave, its drawing with dimensions is presented below.

To amplify the signal in this design, a ready-made SWA 9 unit is used, if there are problems with its acquisition, you can use homemade device, the scheme of which was given above (see Fig. 2).

It is important to observe the angle between the petals, going beyond the specified range significantly affects the quality of the "picture".

Despite the fact that such a device is much simpler than the log-periodic design with a wave channel, nevertheless, it shows good results if the signal is of sufficient power.

DIY antenna eight for digital TV

Consider another common design option for receiving “numbers”. The basis is the classical scheme for the UHF range, due to its shape called the "Eight" or "Zigzag".

Fig. 6. Sketch and implementation of the digital eight

Dimensions of the structure:

• the outer sides of the rhombus (A) - 140 mm;
• inner sides (B) - 130 mm;
• distance to the reflector (C) - from 110 to 130 mm;
• width (D) - 300 mm;
• the pitch between the rods (E) is from 8 to 25 mm.

The cable connection point at points 1 and 2. The requirements for the material are the same as for the “Rhombus” design, which was described at the beginning of the article.

Homemade Antenna for DBT T2

Actually, all the examples listed above are capable of taking DBT T2, but for a change, we give a sketch of another design, popularly called the “Butterfly”.

As a material, you can use plates of copper, brass, aluminum or duralumin. If the structure is planned to be installed on the street, then the last two options are not suitable.

Bottom line: which option to stop?

Oddly enough, but the simplest option is the most effective, so the "loop" is best suited for receiving "numbers" (Fig. 4). But, if you want to receive other channels in the decimeter range, it is better to stop at the Zigzag (Fig. 6).

The antenna for the TV should be directed towards the nearest active repeater, to select the desired position, you should rotate the design until the signal strength is satisfactory.

If, despite the presence of an amplifier and reflector, the quality of the "picture" is poor, you can try to install the design on the mast.

In this case, it is necessary to establish lightning protection, but this is the topic of another article.

Digital signals have been known to everyone for a long time. All tele-organizations switched to new format. Analog television devices stepped aside. But despite this, quite a few are in working condition and can last for more than one year. In order for obsolete equipment to finalize the allotted service life, while presenting the opportunity to watch digital broadcasting, you will need to connect DVB-T to a television set and catch wave signals with a zigzag antenna.

For those who want to save the family budget and still get high-quality television broadcasting, you need to pay attention to the Harchenko antenna for digital TV with your own hands.

This unique design has been known for a long time, but has found itself relatively recently.

The principle of operation of the antenna for digital television

After the appearance of radio communications, the relevance of the use of the antenna device has increased. From the 60s of the twentieth century, at that time, the recognizable engineer Kharchenko flaunted a design of 2 rhombuses. Such a device allowed him to catch US ethers.

This is a double square made of thick copper wire. The squares are connected due to open angles with each other, in this place the cable from the TV is connected. To increase the directivity, a grille of material capable of conducting current is mounted at the rear.

The perimeter of the squares is equal to the wavelength at which reception is tuned. About 12 mm should be the diameter of the wire for broadcasting from 1 to 5 TV channels. The design is far from compact, in the case of an assembly for radio communications and TV meter range up to 12 channels.

To facilitate the device, 3 laying of wires of a smaller cross section was involved. Despite this, the size and weight remained impressive.

The antenna in question received a second wind when broadcasting appeared in the UHF range. Most people know rhombuses, triangles and other home-made figures in the form of antenna devices for receiving a decimeter wave signal. The antennas of such a plan were merry on the balconies, the windows of both private houses and multi-story buildings.

In the early 2000s, American professor Trevor Marshall came up with a proposal to use this design in Bluetooth and Wi-Fi networks.

A biquadratic antenna is also an antenna device of a Soviet engineer. This option is created according to the same principles as a regular biquadrat. A distinctive feature is that at the vertices of the squares there are additional squares instead of corners.

As for the sizes of these squares, they are identical to the usual ones. This avoids additional calculations. It is enough to use the calculation of the standard biquadrat.

Recall that the wires in the place where they intersect, require isolation from each other.

Necessary materials and tools

Kharchenko’s television antenna for DVB T2 is economical enough. In order to assemble the structure, such details as:

• Wire;
• Coaxial cable;
• Wooden rail.

As for the tools: pliers, hammer, sharp knife. If you plan to attach the antenna device to a wall or other surface, most likely you will need a drill for mounting.

Antenna Calculation

Before proceeding with the design, it will be necessary to calculate the Kharchenko antenna. This will allow you to assemble an effective device with maximum accuracy. The dimensions of the zigzag antenna DVB T2 play a significant role in increasing signal reception.

As technology has stepped forward, now there is no need to leaf through manuals, look for formulas for calculating dimensions. And even more so, to carry out complex mathematical calculations in order to correctly develop a sketch or a future drawing.

After that, you get information: about the required length of the copper wire, its sides, diameter.

Harchenko antenna assembly for digital TV

Step-by-step instructions that will allow you to quickly assemble your own Kharchenko antenna for digital tv:

1. Determine the polarization and frequency of the wave. The device must be linear.
2. The biquadratic type of zigzag antenna device is made of copper. All elements are located at the corners, one of them they are in contact. For horizontal polarization, the figure eight must stand upright. If vertical polarization is done, the structure rests on its side.

1. The side of the square is calculated according to a special formula - the wavelength, which is divided into four.
2. Imagine the structure, it should be oval in shape, while pulled along the center across the larger side. The sides do not touch, but are in close proximity to each other.
3. We bring the antenna cable to the points of proximity on both sides. It will be necessary to block one direction of the diagram; for this, a fetal screen made of copper is mounted; it will be located at a distance of 0.175 from the working wavelength. Put it on the braid of the cable.

As for the reflector, earlier it was made of textolite boards, which were coated with copper. Today, this component is made from metal plates. It is by this principle that the design for receiving digital television is made. Nothing complicated. Everything you need is at hand.

Antenna Testing

The device is created, it's time to check the effectiveness of the work done. To test the reception quality of the wave channel, you must connect the antenna to the receiver. Turn on the TV and receiver.

Open the main menu of the console, select automatic search channels. On average, this process takes only a few minutes. You can also find channels manually, but for this you will have to enter their frequency. To test the design of Harchenko for the TV, just evaluate the quality of the broadcast. If the channels show well, then the work is done correctly.

What if interference is visible? Rotate the TV antenna and see if picture quality improves. When the optimal location is determined, simply lock the device. Naturally, it should be directed towards the TV tower.

Note.

Once upon a time, a good television antenna was in short supply, bought for quality and durability, to put it mildly, did not differ. To make an antenna for a “box” or “coffin” (an old tube TV) with one's own hands was considered an indicator of skill. Interest in homemade antennas is not dying away today. There is nothing strange here: the conditions for receiving TV have changed dramatically, and manufacturers, believing that in the theory of antennas there is nothing essentially new and will not, will most often adapt electronics to long-known designs without thinking about the fact that The main thing for any antenna is its interaction with the signal on the air.

What has changed on the air?

Firstly, almost the entire volume of TV broadcasting is currently carried out in the UHF range. First of all, for economic reasons, the antenna-feeder economy of the transmitting stations is much simplified and cheapened, and, more importantly, the need for its regular maintenance by highly qualified specialists engaged in heavy, harmful and dangerous work.

Second - TV transmitters now cover almost all more or less populated areas with their signal, and a developed communication network ensures the flow of programs to the most remote corners. There, broadcasting in the inhabited area is provided by low-power maintenance-free transmitters.

Third the conditions for the propagation of radio waves in cities have changed. At UHF, industrial noise seeps weakly, but reinforced concrete high-rise buildings are good mirrors for them, repeatedly reflecting the signal up to its complete attenuation in the area of \u200b\u200bseemingly reliable reception.

Fourth - There are a lot of TV programs on air now, tens and hundreds. How diverse and meaningful this set is is another question, but counting on receiving 1-2-3 channels is now pointless.

Finally, digital broadcasting has been developed. The DVB T2 signal is a special thing. Where it is still at least a little bit, by 1.5-2 dB, exceeds the noise, the reception is excellent, as if nothing had happened. And a little further or to the side - no, as cut off. The “figure” is almost insensitive to interference, but if there is a mismatch with the cable or phase distortion anywhere in the path, from the camera to the tuner, the picture may scatter in squares and with a strong clear signal.

Antenna Requirements

In accordance with the new reception conditions, the basic requirements for TV antennas have also changed:

• Its parameters such as directivity coefficient (LPC) and protective coefficient (LPC) do not have a decisive significance now: the modern broadcast is very dirty, and along the tiny side lobe of the directivity pattern (LPS), at least some kind of interference will crawl through, and It is necessary to deal with it by electronic means.
• In return, the own antenna gain (KU) gains particular importance. An antenna that "catches" the ether well, and does not look at it through a small hole, will provide the power reserve of the received signal, allowing the electronics to clean it of noise and interference.
• A modern television antenna, with rare exceptions, should be a band antenna, i.e. its electrical parameters should be preserved naturally, at the level of theory, and not squeezed into an acceptable framework by engineering tricks.
• The TV antenna must be matched in cable over its entire operating frequency range without additional devices harmonization and balancing (CSS).
• The frequency response of the antenna (AFC) should be as smooth as possible. Sharp surges and dips will certainly be accompanied by phase distortion.

The last 3 points are due to the requirements of receiving digital signals. Customized i.e. operating theoretically at one frequency, antennas can be “stretched” in frequency, for example. antennas of the “wave channel” type on the UHF with an acceptable signal-to-noise ratio capture 21-40 channels. But their coordination with the feeder requires the use of CSS, which either strongly absorb the signal (ferrite) or spoil the phase response at the edges of the range (tuned). And such an antenna, which works perfectly on the “analogue”, will take the “figure” badly.

In this regard, from all the great antenna diversity, this article will consider the antennas for the TV, available for self-manufacturing, of the following types:

1. Frequency-independent (all-wave) - It does not differ in high parameters, but it is very simple and cheap, it can be done in literally an hour. Outside the city, where the ether is cleaner, it will be able to take a number or a fairly powerful analogue not far from the television center.
2. Range log-periodic. It, figuratively speaking, can be likened to a fishing trawl, already when catching sorted prey. It is also quite simple, fits perfectly with the feeder in its entire range, absolutely does not change the parameters in it. Technical parameters are average, therefore it is more suitable for a summer residence, and in the city as a room.
3. Several modifications of the zigzag antenna, or Z-antennas. In the MV range, this is a very solid construction, requiring considerable skill and time. But on the UHF, due to the principle of geometric similarity (see below), it is so simplified and cringed that it can be used as a highly efficient indoor antenna under almost any reception conditions.

Note: The Z-antenna, if you use the previous analogy, is a frequent ravine, raking everything that is in the water. As the air was littering, it was no longer in use, but with the development of digital TV it was again on the horse - in its entire range it is just as well coordinated and holds parameters as a “speech therapist”.

Exact matching and balancing of almost all the antennas described below is achieved by laying the cable through the so-called. point of zero potential. It is subject to special requirements, which will be discussed in more detail below.

About vibrator antennas

In the frequency band of one analog channel, you can transmit up to several dozen digital. And, as already mentioned, the figure works with an insignificant signal-to-noise ratio. Therefore, in places very far from the television center, where the signal of one or two channels is barely reaching, a good old wave channel (AVK, wave channel antenna) can be used from a class vibrator antennas, so in the end we will give a few lines to her.

About satellite reception

Do it yourself satellite dish there is no point. You still need to buy a head and tuner, and behind the external simplicity of the mirror lies a parabolic oblique fall surface, which not every industrial enterprise can perform with the necessary accuracy. The only thing that the do-it-yourselfers can do is set up a satellite dish, about that.

About antenna options

Accurate determination of the above-mentioned parameters of the antennas requires knowledge of higher mathematics and electrodynamics, but it is necessary to understand their significance when proceeding with the manufacture of the antenna. Therefore, we give a somewhat crude, but nevertheless explaining the meaning of the definition (see. Fig. To the right):

• KU - the ratio of the received antenna to the main (main) lobe of its DN signal power, to its own power, received in the same place and at the same frequency non-directional, with a circular, DN, antenna.
• KND - the ratio of the solid angle of the entire sphere to the solid angle of the opening of the main lobe of the DN, under the assumption that its cross section is a circle. If the main petal has different sizes in different planes, you need to compare the area of \u200b\u200bthe sphere and the cross-sectional area of \u200b\u200bthe main petal with it.
• KZD - the ratio of the received signal power to the main lobe to the sum of the interference powers at the same frequency, adopted by all side (back and side) lobes.

Notes:

1. If the antenna is a range antenna, the powers are considered at the frequency of the wanted signal.
2. Since there are no completely non-directional antennas, a half-wave linear dipole oriented in the direction of the electric field vector (according to its polarization) is taken as such. Its KU is considered equal to 1. TV programs are transmitted with horizontal polarization.

It should be remembered that KU and KND are not necessarily interrelated. There are antennas (for example, "spyware" - a single-wire traveling wave antenna, ABV) with a high directivity, but a single or lower gain. Such look into the distance as if through a diopter sight. On the other hand, there are antennas, e.g. Z-antenna, in which a low directivity is combined with significant gain.

About the intricacies of manufacturing

All elements of the antennas through which the useful signal currents flow (specifically, in the descriptions of individual antennas) must be connected by soldering or welding. In any outdoor assembly, the electrical contact will soon be broken, and the antenna parameters will deteriorate sharply, up to its complete unsuitability.

This is especially true for points of zero potential. According to experts, a voltage node and current antinode are observed in them, i.e. its greatest importance. Current at zero voltage? No wonder. Electrodynamics gone from Ohm's law on direct current as far as the T-50 from a kite.

Places with zero potential points for digital antennas are best done in bent solid metal. A small “creeping” current in welding when receiving an analog in the picture, most likely, will not affect. But, if a figure is adopted at the noise boundary, then the tuner may not see the signal because of the “creep”. Which at a pure current in antinodes would give a stable reception.

About cable soldering

The braid (and the central core is often) of modern coaxial cables are made not of copper, but of corrosion-resistant and inexpensive alloys. They are poorly soldered, and if you warm for a long time, you can burn the cable. Therefore, you need to solder the cables with a 40-W soldering iron, fusible solder and with flux paste instead of rosin or alcohol rosin. You don’t need to feel sorry for the paste, solder immediately spreads along the veins of the braid only under a layer of boiling flux.

Types of antennas

All-wave

An all-wave (more precisely, frequency-independent, ANA) antenna is shown in Fig. She is two triangular metal plates, two wooden slats, and many enameled copper wires. The diameter of the wire does not matter, and the distance between the ends of the wires on the rails is 20-30 mm. The gap between the plates to which the other ends of the wires are soldered is 10 mm.

Note: instead of two metal plates, it is better to take a square of one-sided foil fiberglass in triangles cut out of copper.

The width of the antenna is equal to its height, the opening angle of the canvases is 90 degrees. The layout of the cable is shown in the same figure. The point marked in yellow is the point of quasi-zero potential. It is not necessary to solder the braid of the cable to the cloth in it, it is enough to tie it up tightly, for coordination there will be enough capacity between the braid and the cloth.

The PNA, stretched in a window 1.5 m wide, receives all meter and DCM channels from almost all directions, except for a dip of about 15 degrees in the plane of the canvas. This is its advantage in places where it is possible to receive signals from different television centers, no need to rotate. Disadvantages - a single KU and zero KZD, therefore, in the interference area and outside the coverage area, the PRA is not suitable.

Note : there are other types of PRA, for example. in the form of a two-turn logarithmic spiral. It is more compact than the PNA from triangular canvases in the same frequency range, therefore it is sometimes used in technology. But in everyday life this does not give advantages, it is more difficult to make a spiral PNA, it is more difficult to coordinate with a coaxial cable, therefore we do not consider it.

On the basis of the PNA, a very popular once-used fan vibrator (horns, flyer, slingshot) was created, see fig. Its KND and KZD are something about 1.4 with a fairly smooth frequency response and linear phase response, so for a figure, he would be suitable now. But - it works only on MV (1-12 channels), and digital broadcasting goes to UHF. However, in the village, when climbing 10-12 m, it may be suitable for receiving an analogue. The mast 2 may be of any material, but the mounting strips 1 - of a good non-soaking dielectric: fiberglass or fluoroplastic with a thickness of at least 10 mm.

Beer Vsevolnovka

The beer can’s all-wave antenna is clearly not the fruit of the hangover hallucinations of a drunken radio amateur. This is really a very good antenna for all reception cases, you just need to do it correctly. And it’s exceptionally simple.

The basis of its design is the following phenomenon: if you increase the diameter of the shoulders of a conventional linear vibrator, then the working band of its frequencies expands, and other parameters remain unchanged. In long-distance radio communications since the 20s, the so-called. Dipole Nadenenko based on this principle. And beer cans in size are just suitable as the shoulders of a vibrator on a DMV. In essence, the PRA is a dipole whose shoulders expand indefinitely to infinity.

The simplest beer vibrator of two cans is suitable for indoor reception of an analog in the city even without coordination with the cable, if its length is not more than 2 m, on the left in Fig. And if we assemble a vertical common-mode grating from beer dipoles in half-wave increments (on the right in the figure), coordinate it and balance it with an amplifier from the Polish antenna (we will talk about it later), then thanks to vertical compression of the main lobe of the beam, this antenna will give good ku.

The gain of the “brewery” can be further increased by adding a KZD at the same time if you place a screen from the grid at the back of it at a distance equal to half the grid pitch. The beer grate is mounted on a mast made of dielectric; mechanical connections between the screen and the mast are also dielectric. The rest is clear from the trace. fig.

Note: the optimal number of floors of the lattice is 3-4. With 2 gain in gain will be small, and more difficult to coordinate with the cable.

Video: making the simplest beer can antenna

"Speech therapist"

A log-periodic antenna (LPA) is a collecting line to which halves of linear dipoles are alternately connected (i.e., pieces of a conductor with a length of a quarter of the working wave), the length and distance between which vary exponentially with an indicator less than 1, in the center of Fig. The line can be either configured (with a short circuit at the opposite end from the cable connection point), or free. An LPA on a free (non-tuned) line for receiving a digit is preferable: it goes longer, but its frequency response and phase response are smooth, and the coordination with the cable does not depend on the frequency, so we will stop on it.

An LPA can be manufactured at any frequency range up to 1-2 GHz. When the working frequency changes, its active region of 1-5 dipoles shifts back and forth along the canvas. Therefore, the closer the progression indicator is to 1, and the antenna’s aperture angle is correspondingly smaller, the greater the gain it will give, but its length will increase. At the UHF, from the external LPA it is possible to achieve 26 dB, and from room - 12 dB.

LPA can be said to be perfect in terms of the totality of qualities digital antenna Therefore, let us dwell on its calculation in more detail. The main thing you need to know is that an increase in the progression index (tau in the figure) gives an increase in gain, and a decrease in the opening angle of the LPA (alpha) increases the directivity. The screen for the LPA is not needed, it almost does not affect its parameters.

Calculation of digital LPA has features:

1. They start it, for the sake of reserve in frequency, from the second longest vibrator.
2. Then, taking the reciprocal of the progression index, the longest dipole is calculated.
3. After the shortest, based on a given frequency range, dipole, add one more.

Let us illustrate with an example. Let's say our digital programs are in the range of 21-31 TCEs, i.e. at 470-558 MHz in frequency; wavelengths, respectively - 638-537 mm. Also suppose that we need to receive a weak noisy signal far from the station, so we take the maximum (0.9) indicator of progression and the minimum (30 degrees) opening angle. To calculate, you need half the opening angle, i.e. 15 degrees in our case. Opening can be further reduced, but the length of the antenna prohibitively, according to the cotangent, will increase.

We consider B2 in the figure: 638/2 \u003d 319 mm, and the shoulders of the dipole will be 160 mm each, up to 1 mm can be rounded. The calculation will need to be carried out until Bn \u003d 537/2 \u003d 269 mm is obtained, and then another dipole is calculated.

Now we consider A2 as B2 / tg15 \u003d 319 / 0.26795 \u003d 1190 mm. Then, through the progression indicator, A1 and B1: A1 \u003d A2 / 0.9 \u003d 1322 mm; B1 \u003d 319 / 0.9 \u003d 354.5 \u003d 355 mm. Next, sequentially, starting from B2 and A2, we multiply by an indicator until we reach 269 mm:

• B3 \u003d B2 * 0.9 \u003d 287 mm; A3 \u003d A2 * 0.9 \u003d 1071 mm.
• B4 \u003d 258 mm; A4 \u003d 964 mm.

Stop, we already have less than 269 mm. We check to see if we can keep up with the gain, although it is so clear that there isn’t: to get 12 dB or more, the distances between the dipoles should not exceed 0.1-0.12 wavelengths. In this case, we have for A1 A1-A2 \u003d 1322 - 1190 \u003d 132 mm, and this is 132/638 \u003d 0.21 wavelength B1. It is necessary to “tighten” the indicator to 1, to 0.93-0.97, so we try different ones, until the first difference A1-A2 is reduced by half or more. For a maximum of 26 dB, the distance between the dipoles at 0.03-0.05 wavelengths, but not less than 2 dipole diameters, 3-10 mm per DMV, is needed.

Note: we cut the remainder of the line behind the shortest dipole, it is needed only for calculation. Therefore, the actual length of the finished antenna will be only about 400 mm. If our LPA is external, this is very good: you can reduce the opening by getting a greater focus and protection from interference.

Video: DVB T2 Digital TV Antenna

About the line and mast

The diameter of the tubes of the line LPA on DMV - 8-15 mm; the distance between their axes is 3-4 diameters. Let us also take into account that thin “shoelaces” cables give such attenuation per meter on the DMV that all antenna-amplification tricks come to naught. Coaxial for outdoor antenna you need to take a good one, with a diameter of 6-8 mm along the shell. That is, the tubes for the line must be thin-walled seamless. It is impossible to tie the cable to the line from the outside, the quality of the LPA will drop sharply.

Of course, it is necessary to fasten the external LPA to the mast for the center of gravity, otherwise the low windage of the LPA will turn into a huge and shaking one. But you cannot connect a metal mast directly to the line either: you must provide a dielectric insert of at least 1.5 m in length. The quality of the dielectric does not play a big role here, the prolific and painted wood will go.

About the Delta Antenna

If the DMV LPA is consistent with the amplifier cable (see below, on Polish antennas), then the shoulders of a meter dipole can be attached to the line, linear or fan, like a slingshot. Then we get a universal MV-DMV antenna of excellent quality. This solution was used in the popular Delta antenna, see fig.

Antenna "Delta"

Zigzag on air

A Z-antenna with a reflector gives amplification and short-circuit efficiency are the same as an LPA, but its main lobe is more than twice as wide horizontally. This can be important in the countryside when there is TV reception from different directions. A decimeter Z-antenna has a small size in terms of, which is essential for indoor reception. But its operating range is theoretically not unlimited, the frequency overlap while maintaining parameters acceptable for the digit is up to 2.7.

The design of the Z-antenna MV is shown in Fig. the cable routing is highlighted in red. In the same place at the bottom left there is a more compact annular variant, colloquially - “spider”. It is clearly seen from it that the Z-antenna was born as a combination of a PNA with a range vibrator; there is something in it from the rhombic antenna, which does not fit into the topic. Yes, the spider ring does not have to be wooden; it can be a metal hoop. "Spider" receives 1-12 MV channels; NAM without reflector is almost circular.

The classic zigzag works either on 1-5 or 6-12 channels, but only wooden slats, a copper enameled wire cd \u003d 0.6-1.2 mm and a few scraps of foil fiberglass are needed for its manufacture, so we give the dimensions through fraction for 1-5 / 6-12 channels: A \u003d 3400/950 mm, B, C \u003d 1700/450 mm, b \u003d 100/28 mm, B \u003d 300/100 mm. At point E - zero potential, here it is necessary to solder the braid with a metallized base plate. The dimensions of the reflector are also 1-5 / 6-12: A \u003d 620/175 mm, B \u003d 300/130 mm, G \u003d 3200/900 mm.

The Z-band antenna with a reflector gives a gain of 12 dB, tuned to one channel - 26 dB. In order to build a single-channel based on a range zigzag, you need to take the side of the square of the canvas in the middle of its width to a quarter of the wavelength and recalculate proportionally all other sizes.

Folk zigzag

As you can see, the MV Z-antenna is a rather complicated structure. But its principle shows itself in all its splendor on the DMV. The UHF Z-antenna with capacitive inserts, combining the advantages of “classics” and “spider,” is so simple to make that it still earned the title of people in the USSR, see fig.

Material - copper tube or aluminum sheet from 6 mm thick. Lateral squares made of metal, either tightened with a net or covered with a tin. In the last two cases, they need to be soldered along the contour. The coaxial cannot be sharply bent, so we drive it so that it reaches the lateral angle, and then does not go beyond the capacitive insert (side square). In vol. A (point of zero potential), the cable sheath is electrically connected to the web.

Note: aluminum is not soldered by ordinary solders and fluxes, so aluminum "folk" is suitable for outdoor installation only after sealing the electrical connections with silicone, because it is all screwed on.

Video: example of a double triangular antenna

Wave channel

The wave channel antenna (AVK), or the Udo-Yagi antenna available for self-manufacturing, is able to give the greatest KU, KND and KZD. But it can only receive a digit on UHF on 1 or 2-3 adjacent channels, because belongs to the class of acutely tuned antennas. Its parameters outside the tuning frequency are deteriorating sharply. AVK is recommended for use with very poor reception conditions, with a separate one for each TCE. Fortunately, this is not very difficult - AVK is simple and cheap.

The basis of the AVK is “raking” the electromagnetic field (EMF) of the signal to the active vibrator. Outwardly small, light, with minimal windage, the AVK can have an effective aperture of tens of wavelengths of the operating frequency. Shortened and therefore having capacitive impedance (impedance) directors (guides) direct the EMF to the active vibrator, and a reflector (reflector), elongated, with inductive impedance, discards what has passed by it. A reflector in AVK needs only 1, but directors can be from 1 to 20 or more. The more of them, the higher the gain of the AVK, but already the band of its frequencies.

From interaction with the reflector and directors wave impedance The active (from which the signal is taken) vibrator drops the more, the closer the antenna is tuned to the maximum gain, and coordination with the cable is lost. Therefore, the AVK active dipole is looped; its initial wave impedance is not 73 Ohms, as in a linear, but 300 Ohms. At the cost of reducing it to 75 Ohm AVK with three directors (five-element, see the figure on the right), it is possible to adjust almost to a maximum gain of 26 dB. Typical for AVK DN in the horizontal plane is shown in Fig. at the beginning of the article.

AVK elements are connected to the boom at points of zero potential, so the mast and boom can be any. Propylene pipes are very suitable.

Calculation and adjustment of AVK for analogue and number are somewhat different. For an analog, the wave channel needs to be counted on the carrier frequency of the image Fи, and for the figure - in the middle of the TCE spectrum Fс. Why so - here, unfortunately, there is no place to explain. For the 21st TCEs, Fi \u003d 471.25 MHz; Fc \u003d 474 MHz. UHF UHFs are located close to each other through 8 MHz, therefore their tuning frequencies for AVKs are calculated simply: Fn \u003d Fи / Fс (21 TCEs) + 8 (N - 21), where N is the number of the desired channel. E.g. for 39 TCEs, Fi \u003d 615.25 MHz, and FS \u003d 610 MHz.

In order not to record a lot of digits, it is convenient to express the dimensions of the AVK in fractions of the wavelength of the working wave (it is considered as L \u003d 300 / F, MHz). The wavelength is usually denoted by the small Greek letter lambda, but since there is no default Greek alphabet on the Internet, we will conventionally denote it by the large Russian L.

The dimensions of the AVK optimized for the figure, according to the figure, are as follows:

• P \u003d 0.52L.
• B \u003d 0.49L.
• D1 \u003d 0.46L.
• D2 \u003d 0.44L.
• D3 \u003d 0.43l.
• a \u003d 0.18L.
• b \u003d 0.12L.
• c \u003d d \u003d 0.1L.

If you do not need a lot of gain, but more importantly, reducing the dimensions of the AVK, then D2 and D3 can be removed. All vibrators are made from a tube or rod with a diameter of 30-40 mm for 1-5 TCEs, 16-20 mm for 6-12 TCEs and 10-12 mm on UHF.

AVK requires precise coordination with the cable. It is the careless execution of the matching and balancing device (CSS) that accounts for the majority of amateur failures. The simplest CSS for AVK - U-loop from the same coaxial cable. Its construction is clear from fig. on right. The distance between the signal terminals is 1-1 140 mm for 1-5 TCEs, 90 mm for 6-12 TCEs and 60 mm on UHF.

Theoretically, the knee length l should be half the length of the working wave, and it appears in most publications on the Internet. But the EMF in the U-loop is concentrated inside the cable filled with insulation, so it is necessary (especially for the numbers - especially necessary) to take into account its shortening factor. For 75-ohm coaxials, it ranges from 1.41-1.51, i.e. l You need to take from 0.355 to 0.330 wavelengths, and take exactly that AVK was AVK, and not a set of pieces of iron. The exact value of the shortening factor is always on the cable certificate.

Recently, domestic industry began to produce reconfigurable AVK for numbers, see Fig. The idea, I must say, is excellent: moving the elements along the arrow, you can fine-tune the antenna to local reception conditions. It is better, of course, for a specialist to do this - the element-wise configuration of the AVK is interdependent, and the amateur will certainly get confused.

About the "Poles" and amplifiers

For many users, Polish antennas, previously decently accepting an analogue, refuse to take a digit - it breaks, or even completely disappears. The reason, I apologize, is the obscene-commercial approach to electrodynamics. It’s a shame sometimes for colleagues who have made such a “miracle”: the frequency response and phase response are either like a psoriasis hedgehog or a horse crest with broken teeth.

The only thing that is good in the "Polish" is their amplifiers for the antenna. Actually, they do not give these products inglorious to die. Amplifiers of the "bands", firstly, low-noise broadband. And, more importantly, with a high resistance input. This allows for the same intensity of the EMF signal in the air to feed several times more power to the tuner input, which allows the electronics to “tear out” a figure from absolutely ugly noises. In addition, due to the large input resistance, the Polish amplifier is an ideal CSS for any antennas: no matter what you hook on to the input, the output is exactly 75 Ohms without reflection and creeping.

However, with a very bad signal, outside the zone of reliable reception, the Polish amplifier no longer pulls. Power is supplied to it via a cable, and the decoupling of the power takes away 2-3 dB of signal-to-noise ratio, which may just not be enough for the figure to go in the outback. Here you need a good TV amplifier with separate power supply. It will most likely be located near the tuner, and the CSS for the antenna, if required, will have to be done separately.

The circuit of such an amplifier, which showed almost 100% repeatability even when performed by beginner amateur radio amateurs, is shown in Fig. Gain control - potentiometer P1. Interchange chokes L3 and L4 - standard purchased. Coils L1 and L2 are dimensioned on the wiring diagram to the right. They are part of the bandpass signal filters, so small deviations of their inductance are not critical.

However, the topology (configuration) of the installation must be observed exactly! And just as mandatory, a metal shield (metal shield), which separates the output circuit from the other circuit.

Where to begin?

We hope that experienced masters will find in this article a certain amount of useful information. And for beginners who do not yet feel the ether, it is best to start with a beer antenna. The author of the article, by no means an amateur in this field, was at one time quite surprised: the simplest “beer” with ferrite matching, as it turned out, also takes the CF no worse than the tested “slingshot”. And what is worth doing one and the other - see text.

(2 ratings, average: 4,00 out of 5)

said (a):

And on the roof there was a satisfactory reception in the Polish. I have 70 to 80 kilometers to the telecentre. These are my problems. From the balcony, it is possible to catch 3 to 4 pieces from 30 channels, and even with the “cubes”. I sometimes watch TV channels from the Internet on a computer in my room, and my wife on my TV cannot normally watch my favorite channels. Neighbors advise to carry out cable, but you have to pay for it every month, and I already pay for the Internet, and the pension is not rubber. We pull it all, pull it and there’s not enough for everything.

Peter Kopitonenko said:

I can’t put the antenna on the roof of the house, the neighbors swear that I walk and break the roofing roofing and the ceiling then leaks. Actually, I’m very “grateful” to the economist who received a prize for saving himself. I decided to remove the expensive gable roof from the houses and replace it with a flat roof covered with a bad roofing material. The economist received money for saving, and people on the upper floors are now tormented all their lives. Water flows on their heads and on the bed. Every year they change the roofing material, and it becomes unusable during the season. In frosty weather, it cracks and rainwater and snow flow into the apartment, even if no one walks on the roof !!!

Sergey said:

Greetings!
Thanks for the article, but who is the author (I don’t see the signature)?
The LPA according to the above method works fine, UHF 30 and 58 channels. Checked in the city (reflected signal) and in the country, the distance to the transmitter (1 kW), respectively: 2 and 12 km approximately. Practice has shown that there is no urgent need for the “B1” dipole, but another dipole before the shortest affects significantly, judging by the signal intensity in%. Especially in a city where you need to catch (in my case) a reflected signal. only I made an antenna with “KZ”, it happened, just there was no suitable insulator.
In general, I recommend.

Basil said:

IMHO: people looking for an antenna for receiving ECTV, forget about the LPA. These wide-range antennas were created in the second half of the 50s (!!) of the last century in order to catch foreign television centers while on the shores of the Soviet Baltic. In the magazines of that time, it was bashfully called "ultra-long reception." Well, we loved watching Swedish porn at night on Riga Seaside ...

In terms of destination, I can say the same thing about “double, triple, etc. squares ", as well as any" zigzags. "

Compared with a similar in range and amplification “wave channel” LPA are more bulky and material intensive. Calculation of LPA is complicated, intricate and more likely to be a fortune-telling and adjustment of the results.

If ECTV is broadcasting in your region on neighboring UHF channels (I have 37-38), then the best solution is to find a book on the net: L. Kapchinsky Television antennas (2nd edition, 1979) and make a “wave channel” for a group of UHF channels (if you have broadcasts above 21-41 channels, you will have to recount) described on pages 67 and further (Fig. 39, Table 11).
If the antenna can be simplified to a 15-30 km transmitter by making it four to five elemental, simply without installing the directors D, E and G.

For very close transmitters, I recommend indoor antennas, by the way in the same book on pages 106 - 109 are drawings of wide-range indoor “wave channel” and airborne radios. The “wave channel” is visually smaller, simpler and more elegant with greater gain!

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