Calculation of dvb t2. DIY antenna for receiving digital television of the DVB-T2 standard
Buying a good antenna for your dacha is not always advisable. Especially if she is visited from time to time. The point is not so much the cost, but the fact that after a while it may not be there. Therefore, many people prefer to make an antenna for their dacha themselves. Costs are minimal, quality is good. And the most important point is that a TV antenna can be made with your own hands in half an hour or an hour and then, if necessary, can be easily repeated...
Digital television in the DVB-T2 format is transmitted in the UHF range, and there is either a digital signal or it is not. If the signal is received, the picture is of good quality. Due to this. Any decimeter antenna is suitable for receiving digital television. Many radio amateurs are familiar with the TV antenna, which is called “zigzag” or “figure eight”. This DIY TV antenna can be assembled literally in a matter of minutes.
To reduce the amount of interference, a reflector is placed behind the antenna. The distance between the antenna and the reflector is selected experimentally - according to the “purity” of the picture 
You can attach foil to the glass and get a good signal... 
Copper tube or wire is the best option; it bends well and is easy to bend.
It is very simple to make; the material is any conductive metal: tube, rod, wire, strip, corner. Despite its simplicity, she accepts it well. It looks like two squares (rhombuses) connected to each other. In the original, there is a reflector behind the square for more reliable signal reception. But it is more needed for analog signals. To receive digital television, you can do without it or install it later if the reception is too weak.
Materials
Copper or aluminum wire with a diameter of 2-5 mm is optimal for this homemade TV antenna. In this case, everything can be done in literally an hour. You can also use a tube, corner, strip of copper or aluminum, but you will need some kind of device to bend the frames to the desired shape. The wire can be bent with a hammer, securing it in a vice.
You will also need a coaxial antenna cable of the required length, a plug suitable for the connector on your TV, and some kind of mount for the antenna itself. The cable can be taken with a resistance of 75 Ohms and 50 Ohms (the second option is worse). If you are making a TV antenna with your own hands for installation on the street, pay attention to the quality of the insulation.
The mounting depends on where you are going to hang your homemade antenna for digital television. On the upper floors, you can try to use it as a home decoration and hang it on curtains. Then you need large pins. At the dacha or if you take a homemade TV antenna to the roof, you will need to attach it to a pole. For this case, look for suitable fasteners. To work, you will also need a soldering iron, sandpaper and/or a file, a needle file.
Do you need a calculation?
To receive a digital signal, there is no need to count the wavelength. It is simply advisable to make the antenna more broadband in order to receive as many signals as possible. To do this, some changes were made to the original design (pictured above) (further in the text).
If you wish, you can make a calculation. To do this, you need to find out what wavelength the signal is broadcast on, divide by 4 and get the required side of the square. To obtain the required distance between the two parts of the antenna, make the outer sides of the diamonds slightly longer and the inner ones shorter.
Drawing of a figure-of-eight antenna for receiving digital TV
- The length of the “inner” side of the rectangle (B2) is 13 cm,
- “external” (B1) - 14 cm.
Due to the difference in lengths, a distance is formed between the squares (they should not be connected). The two extreme sections are made 1 cm longer so that you can fold the loop to which the coaxial antenna cable is soldered.
Making a frame
If you count all the lengths, you get 112 cm. Cut off the wire or whatever material you have, take pliers and a ruler, and start bending. The angles should be 90° or so. You can make a little mistake with the lengths of the sides - this is not fatal. It turns out like this:
- The first section is 13 cm + 1 cm per loop. The loop can be bent immediately.
- Two sections of 14 cm each.
- Two 13 cm each, but with a turn in the opposite direction - this is the point of inflection onto the second square.
- Again two 14 cm each.
- The last one is 13 cm + 1 cm per loop.
The antenna frame itself is ready. If everything was done correctly, there will be a distance of 1.5-2 cm between the two halves in the middle. There may be small discrepancies. Next, we clean the loops and the bend point to bare metal (treat it with fine-grain sandpaper), and tin it. Connect the two loops and crimp them with pliers to hold them tightly.
Cable preparation
We take the antenna cable and carefully clean it. How to do this is shown in the step-by-step photo. The cable must be stripped on both sides. One edge will be attached to the antenna. Here we strip it so that the wire sticks out 2 cm. If it turns out more, the excess (later) can be cut off. Twist the screen (foil) and braid into a bundle. It turned out to be two conductors. One is the central monocore of the cable, the second is twisted from many braided wires. Both are needed and need to be tinned.
We solder the plug to the second edge. A length of 1 cm or so is sufficient here. Also form two conductors and tin them.
Wipe the plug in the places where we will solder with alcohol or solvent, and clean it with emery (you can use a needle file). Place the plastic part of the plug on the cable, now you can start soldering. We solder a monocore to the central output of the plug, and a multicore twist to the side output. The last thing is to crimp the grip around the insulation.
Then you can simply screw on the plastic tip and fill it with glue or non-conductive sealant (this is important). While the glue/sealant has not hardened, quickly assemble the plug (screw on the plastic part) and remove the excess compound. So the plug will be almost eternal.
DIY DVB-T2 TV antenna: assembly
Now all that remains is to connect the cable and the frame. Since we were not tied to a specific channel, we will solder the cable to the middle point. This will increase the broadband of the antenna - more channels will be received. Therefore, we solder the second cut end of the cable to the two sides in the middle (those that were stripped and tinned). Another difference from the “original version” is that the cable does not need to be routed around the frame and soldered at the bottom. This will also expand the reception range.
The assembled antenna can be checked. If the reception is normal, you can finish the assembly - fill the solder joints with sealant. If the reception is poor, try first to find a place where the fishing is better. If there are no positive changes, you can try replacing the cable. To simplify the experiment, you can use regular telephone noodles. It costs a penny. Solder the plug and frame to it. Try it with her. If it catches better, it’s a bad cable. In principle, you can work on “noodles”, but not for long - they will quickly become unusable. It is better, of course, to install a normal antenna cable.
To protect the junction of the cable and the antenna frame from atmospheric influences, the soldering points can be wrapped with ordinary electrical tape. But this method is unreliable. If you remember, you can put on several heat-shrinkable tubes before soldering to insulate them. But the most reliable way is to fill everything with glue or sealant (they should not conduct current). As a “case” you can use lids for 5-6 liter water cylinders, ordinary plastic lids for jars, etc. We make indentations in the right places - so that the frame “sits” in them, do not forget about the cable outlet. Fill it with a sealing compound and wait until it sets. That's it, your DIY TV antenna for receiving digital television is ready.
Homemade double and triple square antenna
This is a narrowband antenna, which is used if you need to receive a weak signal. It can even help if a weaker signal is “clogged” by a stronger one. The only drawback is that you need precise orientation to the source. The same design can be made to receive digital television.
You can also make five frames - for a more confident reception 
It is not advisable to paint or varnish - reception deteriorates. This is only possible in close proximity to the transmitter 
The advantages of this design are that reception will be reliable even at a considerable distance from the repeater. You just need to specifically find out the broadcast frequency, maintain the dimensions of the frames and the matching device.
Construction and materials
It is made from tubes or wire:
- 1-5 TV channel MV range - tubes (copper, brass, aluminum) with a diameter of 10-20 mm;
- 6-12 TV channel MV range - tubes (copper, brass, aluminum) 8-15 mm;
- UHF range - copper or brass wire with a diameter of 3-6 mm.
The double square antenna consists of two frames connected by two arrows - upper and lower. The smaller frame is a vibrator, the larger one is a reflector. An antenna consisting of three frames gives a higher gain. The third, smallest square is called the director.
The upper boom connects the middle of the frames and can be made of metal. The lower one is made of insulating material (textolite, gettinax, wooden plank). The frames must be installed so that their centers (the points of intersection of the diagonals) are on the same straight line. And this straight line should be directed towards the transmitter.
The active frame - the vibrator - has an open circuit. Its ends are screwed to a textolite plate measuring 30*60 mm. If the frames are made from a tube, the edges are flattened, holes are made in them and the lower arrow is attached through them.
The mast for this antenna must be wooden. At least the upper part of it. Moreover, the wooden part should start at a distance of at least 1.5 meters from the level of the antenna frames.
Dimensions
All dimensions for making this TV antenna with your own hands are given in the tables. The first table is for the meter range, the second is for the decimeter range.
In three-frame antennas, the distance between the ends of the vibrator (middle) frame is larger - 50 mm. Other sizes are given in the tables.
Connecting an active frame (vibrator) via a short-circuited cable
Since the frame is a symmetrical device, and it must be connected to an asymmetrical coaxial antenna cable, a matching device is required. In this case, a balancing short-circuited loop is usually used. It is made from pieces of antenna cable. The right segment is called the “loop”, the left one is called the “feeder”. A cable is attached to the junction of the feeder and the cable, which goes to the TV. The length of the segments is selected based on the wavelength of the received signal (see table).
A short piece of wire (loop) is cut at one end by removing the aluminum screen and twisting the braid into a tight bundle. Its central conductor can be cut down to insulation, since it does not matter. The feeder is also cut. Here, too, the aluminum screen is removed and the braid is twisted into a bundle, but the central conductor remains.
Further assembly proceeds like this:
- The braid of the cable and the central conductor of the feeder are soldered to the left end of the active frame (vibrator).
- The feeder braid is soldered to the right end of the vibrator.
- The lower end of the cable (braid) is connected to the feeder braid using a rigid metal jumper (you can use wire, just make sure there is good contact with the braid). In addition to the electrical connection, it also sets the distance between sections of the matching device. Instead of a metal jumper, you can twist the braid of the lower part of the cable into a bundle (remove the insulation in this area, remove the screen, roll it into a bundle). To ensure good contact, solder the bundles together with low-melting solder.
- The cable pieces must be parallel. The distance between them is about 50 mm (some deviations are possible). To fix the distance, clamps made of dielectric material are used. You can also attach a matching device to a textolite plate, for example.
- The cable going to the TV is soldered to the bottom of the feeder. Braid is connected to braid, center conductor to center conductor. To reduce the number of connections, the feeder and cable to the TV can be made single. Only in the place where the feeder should end must the insulation be removed so that the jumper can be installed.
This matching device allows you to get rid of noise, blurry contours, and a second blurry image. It is especially useful at a great distance from the transmitter, when the signal is clogged with interference.
Another variation of the triple square
In order not to connect a short-circuited loop, the triple square antenna vibrator is made elongated. In this case, you can connect the cable directly to the frame as shown in the figure. Only the height at which the antenna wire is soldered is determined in each case individually. After the antenna is assembled, “testing” is carried out. The cable is connected to the TV, the central conductor and braid are moved up/down, achieving a better image. In the position where the picture will be clearest, the antenna cable branches are soldered, and the soldering points are insulated. The position can be any - from the bottom jumper to the transition point to the frame.
Sometimes one antenna does not give the desired effect. The signal turns out to be a weak image - black and white. In this case, the standard solution is to install a television signal amplifier.
The simplest antenna for a summer residence is made from metal cans
To make this television antenna, in addition to the cable, you will only need two aluminum or tin cans and a piece of wooden plank or plastic pipe. Cans must be metal. You can take aluminum beer beers, or you can take tin ones. The main condition is that the walls are smooth (not ribbed).
The jars are washed and dried. The end of the coaxial wire is cut - by twisting the braided strands and clearing the central core of insulation, two conductors are obtained. They are attached to banks. If you know how, you can solder it. No - take two small self-tapping screws with flat heads (you can use “fleas” for drywall), twist a loop at the ends of the conductors, thread a self-tapping screw with a washer installed on it through it, and screw it to the can. Just before this you need to clean the metal of the can by removing the deposits using fine-grain sandpaper.
The cans are secured to the bar. The distance between them is selected individually - according to the best picture. You shouldn’t hope for a miracle - there will be one or two channels in normal quality, but maybe not... It depends on the position of the repeater, the “cleanliness” of the corridor, how correctly the antenna is oriented... But as a way out in an emergency, this is an excellent option.
A simple Wi-Fi antenna made from a metal can
An antenna for receiving a Wi-Fi signal can also be made from improvised means - from a tin can. This DIY TV antenna can be assembled in half an hour. This is if you do everything slowly. The jar should be made of metal, with smooth walls. Tall and narrow canning jars work great. If you will be installing a homemade antenna on the street, find a jar with a plastic lid (as in the photo). The cable is an antenna, coaxial, with a resistance of 75 Ohms.
In addition to the can and cable, you will also need:
- RF-N connector;
- a piece of copper or brass wire with a diameter of 2 mm and a length of 40 mm;
- cable with a socket suitable for a Wi-Fi card or adapter.
Wi-Fi transmitters operate at a frequency of 2.4 GHz with a wavelength of 124 mm. So, it is advisable to choose a jar such that its height is at least 3/4 of the wavelength. For this case, it is better that it be more than 93 mm. The diameter of the can should be as close as possible to half the wavelength - 62 mm for a given channel. There may be some deviations, but the closer to the ideal, the better.
Dimensions and assembly
When assembling, a hole is made in the jar. It must be placed strictly at the desired point. Then the signal will be amplified several times. It depends on the diameter of the selected jar. All parameters are shown in the table. You measure the exact diameter of your can, find the right stitch, and have all the right dimensions.
| D - diameter | Lower limit of attenuation | Upper limit of attenuation | Lg | 1/4 Lg | 3/4 Lg |
|---|---|---|---|---|---|
| 73 mm | 2407.236 | 3144.522 | 752.281 | 188.070 | 564.211 |
| 74 mm | 2374.706 | 3102.028 | 534.688 | 133.672 | 401.016 |
| 75 mm | 2343.043 | 3060.668 | 440.231 | 110.057 | 330.173 |
| 76 mm | 2312.214 | 3020.396 | 384.708 | 96.177 | 288.531 |
| 77 mm | 2282.185 | 2981.170 | 347.276 | 86.819 | 260.457 |
| 78 mm | 2252.926 | 2942.950 | 319.958 | 79.989 | 239.968 |
| 79 mm | 2224.408 | 2905.697 | 298.955 | 74.738 | 224.216 |
| 80 mm | 2196.603 | 2869.376 | 282.204 | 070.551 | 211.653 |
| 81 mm | 2169.485 | 2833.952 | 268.471 | 67.117 | 201.353 |
| 82 mm | 2143.027 | 2799.391 | 256.972 | 64.243 | 192.729 |
| 83 mm | 2117.208 | 2765.664 | 247.178 | 61.794 | 185.383 |
| 84 mm | 2092.003 | 2732.739 | 238.719 | 59.679 | 179.039 |
| 85 mm | 2067.391 | 2700.589 | 231.329 | 57.832 | 173.497 |
| 86 mm | 2043.352 | 2669.187 | 224.810 | 56.202 | 168.607 |
| 87 mm | 2019.865 | 2638.507 | 219.010 | 54.752 | 164.258 |
| 88 mm | 1996.912 | 2608.524 | 213.813 | 53.453 | 160.360 |
| 89 mm | 1974.475 | 2579.214 | 209.126 | 52.281 | 156.845 |
| 90 mm | 1952.536 | 2550.556 | 204.876 | 51.219 | 153.657 |
| 91 mm | 1931.080 | 2522.528 | 201.002 | 50.250 | 150.751 |
| 92 mm | 1910.090 | 2495.110 | 197.456 | 49.364 | 148.092 |
| 93 mm | 1889.551 | 2468.280 | 194.196 | 48.549 | 145.647 |
| 94 mm | 1869.449 | 2442.022 | 191.188 | 47.797 | 143.391 |
| 95 mm | 1849.771 | 2416.317 | 188.405 | 47.101 | 141.304 |
| 96 mm | 1830.502 | 2391.147 | 185.821 | 46.455 | 139.365 |
| 97 mm | 1811.631 | 2366.496 | 183.415 | 45.853 | 137.561 |
| 98 mm | 1793.145 | 2342.348 | 181.169 | 45.292 | 135.877 |
| 99 mm | 1775.033 | 2318.688 | 179.068 | 44.767 | 134.301 |
The procedure is as follows:
You can do without an RF connector, but with it everything is much simpler - it’s easier to position the emitter vertically upward, connect the cable going to the router or Wi-Fi card.
Good afternoon, V.Yu.
The visitor in the latest posts with experience on FM radio antennas is me. The antenna turned out to be easy to manufacture and I decided to repeat it for FM reception and compare it with previously made ones, by ear, instrumentation, and ease of use. The goal was to obtain a signal with a minimum of interference for high-quality radio sound in stereo mode. I made two antennas. The first one is made of wire 3 mm thick. The second is made of metal-plastic. Made from metal plastic it turned out to be a little better in terms of the level of received signals. By ear - less low frequencies, more high frequencies and distinctness of each instrument in the orchestra.
Measurement method - there is a receiver with a signal level indicator in decibels. We number the FM stations and look at the level of the received signal from the station in dB, then we sum up all the values. We obtain the numerical value of the antenna based on the received signal level parameter. All antennas were placed under the same directional conditions. A wire on a window 303 cm long in the form of a rectangle with a gap on the larger side of 2 cm (51 cm x 102 cm) - has a value of 491 dB, a directional loop phased loop antenna made of wire - 459 dB, the same one made of metal - 485 dB. As can be seen from the presented values, a metal-plastic antenna is comparable to a full-size frame equal to the wavelength of the middle FM range.
Now on to the manufacturing technology. It is somewhat different from yours and is made without soldering. The base is a rail (30 x 6 x 3 cm). Remained from renovation (2 pieces). Wire antenna - circumference 75 cm (quarter wave mid FM range). Two circles of the same length. We take a light self-tapping screw (not dark - it has a cone head) with a flat head for a Phillips screwdriver. We make a hole in the rail with a drill or other method so that the wire enters the hole with little resistance. You can slightly bend the ends of the wire for this purpose. We insert the two ends of the loop into the hole in the rail and do not connect them to each other (leave 5 mm between the ends of the loop). We do the same with the second loop at the other end of the rail. The distance from the end of the rail is 1 cm. We screw the screws on top of the rail so that the end of the screw fits into the loop wire at the end. This ensures contact of the coax with the frame. We screw the central core of the coaxial and the braiding on different sides of the frame under the self-tapping screws. For example, the central core is on the left, and the braid is on the right in the direction from the beginning of the rail to its end. We lay the coaxial between the frames and attach it to the screws (screw it under the screw head). The second loop is also attached and the ends of the coaxial are secured under the screws securing the second loop. The descent is in the form of a coaxial - I got a length of 7.5 meters, we fasten it under the screws of one of the frames (the central core is on the left, and the braid is on the right. We tighten everything - the screws ensure contact of the wires with each other with the head, and contact with the loop with the end. The distance between with self-tapping screws - 2 cm We connect the other end of the coaxial cable to the receiver through the connector you need. That's it - the antenna is ready.
Metal-plastic differs in manufacturability. 20 mm pipe, also after repair. Bent into a ring without any problems. The length of the loop is 75 - 1.5 cm (as recommended in the article) = 73.5 cm. Attaching the loop to the rail is also a self-tapping screw, but of a larger size so that it goes through the metal-plastic and is well secured to the wood, by 10-15 mm. There is a distance of 1 cm between the ends of one loop. The screws from the end of the loop are still at a distance of 0.5 cm. We get a distance of 2 cm between the screws of one loop. We lay a piece of plastic between the loops and fasten it with screws to the rail, so that the coax can be inserted inside. We connect the coax in the same way as in the first case to the ends of the loop, the central core and the braid. We ground the tube between the antenna loops (connect it to the braid). We insert a piece of coax into the pipe between the loops, connect the c.z. and braid. We also connect the reduction coaxial to the self-tapping screws of one of the loops (central ring and braid). We first clean the ends of the loops from vinyl to aluminum so that the head of the screw presses the wires to the aluminum and at the same time secures the loop to the wooden batten.
Best regards, Andrey
Let's consider the option of how you can catch terrestrial digital television.
The first condition is that in order to receive digital terrestrial television, you must have a TV that supports the new digital format DVB-T2. Then you won't have to buy consoles that cost money.
The second condition is that in order to receive digital terrestrial television, you need any decimeter antenna. This can be either an indoor or outdoor antenna.
Don't be fooled into thinking you need a special digital or some other antenna.
Earlier I told how I made an antenna from a regular radio or TV telescopic antenna.
You can familiarize yourself with this method
In order to find out which channel is broadcasting digital television in your region, you need to go to the website of “Digital Terrestrial Television” http://rtrs.rf. Go to the “Contacts” menu tab. In the window that appears, select your county and city.
Then click on the “Find your CCP” button just below. Even lower, a search result will appear in the window, where a phone number will be indicated where you can call and find out the channel number.
Having found out the frequency at which the broadcast is taking place, we find the length of the antenna that we need to make.
The formula for determining the length of the antenna:
Divide 7500 by the broadcast frequency in Megahertz (MHz). The result obtained is rounded to whole centimeters. This will be the length of the antenna that we have to make.
Let's look at the example of Ulyanovsk. The broadcast frequency in Ulyanovsk is 754,000 kilohertz or 754 megahertz.
This means that we will have the following formula: 7500/754 = 9.94 centimeters, after rounding we get the required antenna length - 10 centimeters.
Let's start making the antenna.
We take a piece of coaxial cable, 75 ohm, ordinary television. On one side we clean it. We insert a standard connector.
We step back a couple of centimeters from the edge of the connector and put a mark. This will be the base of the antenna.
We also remove the braid. We don't need her. We also remove the foil.
What remains is the internally insulated cable. That is, we do not reach the metal part. After this, we bend the cleaned part of the cable at an angle of 90°.
The repeater is located approximately twelve kilometers from the antenna site. This distance allows us to receive a signal to the antenna without an amplifier. We will need an amplifier if the distance exceeds fifteen kilometers. It is advisable to point the antenna towards the repeater.
Let's start setting up the TV. Go to the “Manual Settings” menu. We check the signal level and quality. Let's make sure the signal is good.
If the signal quality for this antenna is poor, try making a more complex, but more efficient antenna, according to THIS article.
Then go to the “Autosearch” menu item. In the next window, select the “Antenna” item, then in the search parameters leave a checkmark in the “Digital channels only” item. Click “Run”.
The search for channels will begin. At the moment, for example, 10 channels are broadcast in the Samara region.
This is how an antenna is made and digital television channels are tuned.
If necessary, you can use the video instructions.
Digital terrestrial television is a good budget alternative to satellite TV. Its main advantages are the ideal picture and sound quality and the absence of a subscription fee. For reception you only need a set-top box (receiver) and an antenna for digital television, and an excellent image is guaranteed with any TV. An impeccable image is achieved through 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 I receive with a digital TV antenna?
The first and second multiplexes (packages) of channels already available today in Moscow and in many regions for free reception include 20 federal ones (Channel One (1TV), “Russia-1”, “TVC”, “NTV”, “Channel 5” (St. Petersburg), "Russia-2", "Russia-24", "Russia-Culture", "Carousel", "OTR" (1st multiplex); "REN-TV", "STS", "Home" ", "TV-3", "SPORT-PLUS", "SPAS", "STAR", "MIR", "TNT", "MUZ-TV" (2nd multiplex). The expansion of the broadcasting area of the third federal multiplex from 10 channels. During 2015, the third multiplex was launched, with a total number 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?
Depending on the location of installation, antennas can be indoor or outdoor, respectively for home and garden. They are also divided into active and passive, depending on the presence of a built-in signal amplifier operating from the network. If you live near a TV tower, a passive (without amplifier) indoor antenna is recommended for reception: amplifying the signal may distort it. When moving away from the television tower, for example, at a dacha or in a country house and there are obstacles (trees, buildings), an outdoor 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, you can find outdoor antennas in the section Outdoor antennas for digital television
Is it possible to make the antenna work for two TVs?
You can connect two or more TVs to one antenna for digital television. However, if you use one receiver for reception, then each TV will show the same channel. To watch different channels at the same time, you need to purchase receivers for other TVs.
The delivery department will deliver the goods you have chosen to any point in Moscow and the Moscow region.
Despite the rapid development of satellite and cable television, the reception of terrestrial television broadcasts still remains relevant, for example, for places of seasonal residence. It is not at all necessary to buy a finished product for this purpose; a home UHF antenna can be assembled with your own hands. Before moving on to considering the designs, we will briefly explain why this particular range of the television signal was chosen.
Why DMV?
There are two good reasons to choose designs of this type:
- The thing is that most channels are broadcast in this range, since the design of repeaters is simplified, and this makes it possible to install a larger number of unattended low-power transmitters and thereby expand the coverage area.
- This range is selected for digital broadcasting.
Indoor TV antenna “Rhombus”
This simple, but at the same time, reliable design was one of the most common in the heyday of on-air television broadcasting.
Rice. 1. The simplest homemade 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.
The material you can use is aluminum, copper, and brass tubes or strips 10-15 mm wide. If you plan to install the structure outdoors, it is better to abandon aluminum, since it is susceptible to corrosion. Capacitive inserts are made of foil, tin or metal mesh. After installation, they are soldered along the circuit.
The cable is laid as shown in the figure, namely: it did not have sharp bends and did not leave the side insert.
UHF 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 a schematic diagram of a device that can be used with almost any antenna.
Rice. 2. Antenna amplifier circuit for the UHF range List of elements:
- Resistors: R1 – 150 kOhm; R2 – 1 kOhm; R3 – 680 Ohm; 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 with: KT3101, KT3115 and KT3132).
Inductance: L1 – is a frameless coil with a diameter of 4 mm, wound with copper wire Ø 0.8 mm (2.5 turns must be made); L2 and L3 are high-frequency chokes 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;
- gain and noise factors – 30 and 3 dB, respectively;
- the value of the output and input resistance of the device corresponds to the RG6 cable - 75 Ohm;
- the device consumes about 12-14 mA.
Let us pay attention to the method of power supply; it is carried out directly through the cable.
This amplifier can work with the simplest designs made from improvised means.
Indoor antenna made from beer cans
Despite the unusual design, it is quite functional, since it is a classic dipole, especially since the dimensions of a standard can are perfectly suitable for the arms 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 is not longer than two meters.
Designations:
- A - two cans with a volume of 500 mg (if you take tin and not aluminum, you can solder the cable instead of using self-tapping screws).
- B – places where the cable shielding is attached.
- C – central vein.
- D – place of attachment of the central core
- E – cable coming from the TV.
The arms of this exotic dipole must be mounted on a holder made of any insulating material. As such, you can use improvised things, for example, a plastic clothes hanger, a mop bar or a piece of wooden beam of the appropriate size. The distance between the shoulders is from 1 to 8 cm (selected empirically).
The main advantages of the design are fast production (10 - 20 minutes) and quite acceptable picture quality, provided there is sufficient signal power.
Making an antenna from copper wire
There is a design that is much simpler than the previous version, which only requires a piece of copper wire. We are talking about a narrow band loop antenna. This 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. A simple UHF loop antenna for receiving digital TV For this design, you need to calculate the length of the loop; to do this, you need to find out the frequency of the “digit” for your region. For example, in St. Petersburg it is broadcast on 586 and 666 MHz. The calculation formula will be as follows: L R = 300/f, where L R is the length of the loop (the result is presented in meters), and f is the average frequency range, for St. Petersburg this value will be 626 (the sum of 586 and 666 divided by 2). Now we calculate L R, 300/626 = 0.48, which means the length of the loop should be 48 centimeters.
If you take a thick RG-6 cable with braided foil, it can be used instead of copper wire to make a loop.
Now let's tell you how the structure is assembled:
- A piece of copper wire (or RG6 cable) with a length equal to L R is measured and cut.
- A loop of suitable diameter is folded, after which a cable leading to the receiver is soldered to its ends. If RG6 is used instead of copper wire, then the insulation from its ends is first removed, approximately 1-1.5 cm (the central core does not need to be cleaned, it is not involved in the process).
- The loop is installed on the stand.
- The F connector (plug) is screwed onto the cable to the receiver.
Note that despite the simplicity of the design, it is most effective for receiving “digits”, provided that the calculations are carried out correctly.
Do-it-yourself MV and UHF indoor antenna
If, in addition to UHF, there is a desire to receive MF, you can assemble a simple multiwave oven, its drawing with dimensions is presented below.
To amplify the signal in this design, a ready-made SWA 9 unit is used; if you have problems purchasing it, you can use a home-made device, the diagram of which was shown above (see Fig. 2).
It is important to maintain 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 a log-periodic design with a wave channel, it nevertheless shows good results if the signal is of sufficient power.
DIY figure eight antenna for digital TV
Let's consider another common design option for receiving “digits”. It is based on the classic scheme for the UHF range, which, because of its shape, is called “Figure Eight” or “Zigzag”.
Rice. 6. Sketch and implementation of the digital eight Design dimensions:
- outer sides of the diamond (A) – 140 mm;
- internal 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 location is at points 1 and 2. The material requirements are the same as for the “Rhombus” design, which was described at the beginning of the article.
Homemade antenna for DBT T2
Actually, all of the examples listed above are capable of receiving DBT T2, but for variety we will present a sketch of another design, popularly called “Butterfly”.
The material can be used as plates made of copper, brass, aluminum or duralumin. If the structure is planned to be installed outdoors, then the last two options are not suitable.
Bottom line: which option to choose?
Oddly enough, the simplest option is the most effective, so the “loop” is best suited for receiving a “digit” (Fig. 4). But, if you need to receive other channels in the UHF range, then it is better to stick with “Zigzag” (Fig. 6).
The antenna for the TV should be directed towards the nearest active repeater, in order to select the desired position, you should rotate the structure until the signal strength is satisfactory.
If, despite the presence of an amplifier and reflector, the quality of the “picture” leaves much to be desired, you can try installing the structure on a mast.
In this case, it is necessary to install lightning protection, but this is a topic for another article.