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.
There are two good reasons to choose designs of this type:
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.
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:
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:
Let's 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.
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:
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 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.
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:
Note that despite the simplicity of the design, it is most effective for receiving “digits”, provided that the calculations are carried out correctly.
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, this design uses a ready-made SWA 9 unit; 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.
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:
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.
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.
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 stop at “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.
If the development of terrestrial digital television continues at this pace, then in the near future satellite television will die as a class. After all, the cost of equipment for its reception is disproportionately less, and anyone can make an antenna at home within 30 minutes, spending no more than 100 rubles on it.
After the article was published, I continued my experiments. And the reason for this was the very good performance of television signal reception. Which prompted me to think that the signal level in my case is strong enough to receive digital terrestrial television in DVB-T2 format, and most likely I can get by with a simpler antenna.
After visiting the official website of the Volgograd branch of the Russian Television and Radio Broadcasting Network, I found out that DVB-T2 broadcasting in Volgograd is carried out from two places. One is the well-known “Mamaev Kurgan”, where the TV and Radio Center is actually located, and the second is “Nagorny” (the village of Nagorny, in fact this is the Krasnoarmeysky district). The distance to the second transmitter in my case is only 5 km. This explains the good signal quality, so you can get by with a simpler antenna.
I began to “dig” the Internet for the simplest antennas of the “pin” type. Which in practice looks like an antenna connector with a piece of bent antenna cable stripped of braid.
Don’t be surprised, but this piece of antenna wire with a connector perfectly picks up a digital television signal of the DVB-T2 standard. With 100% quality. I wrote about my reception conditions and the distance to the television center transmitter in the previous one. The antenna is working!
Here is the data on the signal reception quality of the first multiplex, the result is 100%:
The picture is similar at the second multiplex, the result is again 100%:
I post the photo in such a way that the receiver and the antenna inserted into it can be seen. So that no one thinks this is a joke. And here is a rear view of the antenna inserted into the receiver:
The antenna for receiving digital terrestrial television DVB-T2 is a UHF antenna. Therefore, when calculating its size, you should know for which broadcast channel we are making it. Unfortunately, there is no simple antenna that would receive all television channels equally well.
In my case, the first and second multiplex are broadcast on UHF channel 37 (average frequency 602.5 MHz) and UHF frequency channel 39 (average frequency 618.5 MHz), respectively. And in order for our antenna to satisfactorily receive the signal from both multiplexes, we will tune it to the average frequency of 610.5 MHz.
Determine the average wavelength. Wavelength = speed of light / frequency of TV channel, where the speed of light is 300 thousand km/sec; channel frequency – 610.5 MHz. Thus, wavelength = 300/610.5 = 0.491 m. To make the antenna, we need ¼ of the wavelength, i.e. 0.491/4 = 0.123 m.
Next, take a piece of cable. We disconnect the antenna connector on one side. We retreat about 2 cm from it and cut off the insulation along with the screen. We make the central conductor, together with the insulation, equal to a quarter of the wavelength that we need. For clarity, we use the figure below:
Let me remind you that the distance from my house to the Nagorny transmitter is approximately 5 km, the windows of the room (kitchen) where the antenna is located face the side of the panel house opposite from the TV tower. The antenna works great under these conditions. The signal level and quality of image and sound are not affected by the weather or time of day. The quality is always 100%.
As a digital television signal receiver I used (clearly visible in the photo) a DVB-T2 Supra SDT-92 digital TV receiver and an old POLAR37 CTV4015 TV.
I remembered an institute joke that “antenna theory” (and I had such a subject) is a science that adapts to practice. That is, a craftsman assembled an antenna from beer cans or gaskets from the cylinder head of an internal combustion engine and the pundits sat down to come up with laws and formulas to explain from a scientific point of view why this antenna works.
Kharchenko Konstantin Pavlovich
Born August 11, 1931 In 1950 In Leningrad, he graduated with a medal from secondary school for men No. 158 and entered the S.M. Budyonny Military Engineering Academy of Communications at the radio department. In 1955 enrolled in the head communications institute of the USSR Ministry of Defense. In December 1958 invented his first antenna, which for a long time became the basis of many communications equipment of the USSR Armed Forces and the Warsaw Pact countries. Thanks to the magazine “Radio” (No. 3, 1961), it completely “conquered” the roofs of houses “all over Great Rus'” and far beyond its borders as a television station (popularly “eight”, “zigzag”, “bubnovochka”). Six first degree diplomas from Radio magazine and more than 40 years of cooperation. More than seven years of teaching at the Lensoveta Lensoveta University.
We present to your attention, dear anonymous, a Kharchenko antenna, optimized for receiving digital television. Of course, it is equally suitable for both analog and digital television of any standard, which is broadcast in the UHF range. Why do we position it as a “digital” antenna? Firstly, very little time will pass and you and I will remember analog TV as some kind of antique, like a gramophone. And about “secondly” we should talk in more detail...
Kharchenko's original antenna consists of two square frames with a perimeter of about 1λ, connected in parallel. Such an antenna has a low input impedance of about 75 Ohms, which is very convenient for direct matching with a 75 Ohm feeder, and for balancing it is usually enough to lay this cable along one of the arms of the frame. The Kharchenko antenna, designed for 50 Ohms, is also excellent for the amateur bands 144/433/1296 MHz, for CDMA-800, GSM-900, GSM-1800, WiFi-2400, which is discussed on our website and a couple of online calculators. Please note that TV broadcasting in 1961 was carried out on meter waves and the antenna bandwidth was quite enough to receive 1-2 channels, which was the limit of broadcasting at that time. Gradually, television began to occupy the UHF range. In this case, the bandwidth of the Kharchenko antenna was not enough. 
To solve this problem, more broadband options were proposed for analog TV, which was broadcast in the range 470-622 MHz (21-39 frequency channels). One of the homemade versions of such an antenna, although not very successful, is shown in the figure. Currently, according to the OIRT standard, the range 470-860 MHz (21-69 channels) is allocated for digital television. At the same time, digital multiplexes are often scattered throughout the entire range and relatively narrow-band antennas in this case are not suitable, except perhaps only for receiving one of the multiplexes. To cover such a wide range, you can use other versions of the Kharchenko antenna, which have a higher input impedance. For example, rhombic double loops with a perimeter of one of the loops of about 1.5λ have an input impedance of about 300 Ohms, which makes the antenna more broadband and convenient for matching with 300/75 Ohms matching devices or antenna amplifiers, which are currently widespread on the market. This is exactly the antenna that was developed by a user under the nickname yurik82
through digital optimization in NEC2 and subsequent verification in Ansys HFSS (details at the end of the article). You can download the archive with the 4NEC2 and HFSS models for detailed study. 
The antenna is completely symmetrical along both the vertical and horizontal axes passing through the center of the antenna. All dimensions are indicated from center to center of the wire, i.e. along the axes of the wires. The distance to the reflector is measured from the plane on which the axes of the frame wires are located to the surface of the reflector. Lengths of the sides of the frames (along the axis of the wire):
The result was a simple antenna with an input impedance of 300 Ohms, a gain of 9.5±0.5 dBi and a bandwidth of 470-760 MHz according to the SWR criterion< 2. Антенна проста в изготовлении, имеет очень хорошую повторяемость, не требует настройки и может быть изготовлена своими руками из самых доступных материалов. В сравнении с классической антенной Харченко этот вариант имеет следующие особенности:
Unfortunately, such an antenna does not cover the full range of 470-860 MHz, therefore, if in the area where an anonymous person lives, Some multiplexes operate at frequencies above 750 MHz - it is advisable to recalculate the antenna upwards, reducing all dimensions by 10%, sacrificing the gain on lower channels 21-25. This frame size option is indicated in brackets in the drawing.. The dimensions of the reflector and the gap at the connection point do not change in this case.
In comparison with designs popular on the Internet - the Triple Square and the Turkin antenna - this version of the Kharchenko antenna has undeniable advantages, such as broadband with comparable gain, non-criticality to dimensional accuracy, and ease of manufacture. Moreover, we do not recommend repeating the above-mentioned designs for receiving digital television; you can read more about this. 
With reflector dimensions of 40x50 cm, the aperture utilization factor reaches 130% on the lower channels, i.e. For such amplification, this is a fairly compact antenna and its dimensions are entirely justified by the amplification achieved. The width of the main lobe of the radiation pattern is about 70°. 
As a vibrator, you can use a common copper or aluminum electrical wire of 4 mm 2 (Ø2.25 mm) or 10 mm 2 (Ø3.57 mm), with a reserve of 1.5 meters of wire. A thicker conductor is preferred due to stiffness and additional load-bearing capacity. You can use other available materials - galvanized or brass tapes. As a reflector, you can use galvanized construction mesh with cells 20x20 or 20x50 mm. If the antenna is hidden from the wind (for example, in an attic, balcony, close to the facade), the reflector can be made from solid galvanized tin. It is advisable to mount the tops of the vibrator (points A and B) on metal stands/bolts, then the vibrator will be connected to the reflector and the mast via direct current, which facilitates the flow of static charges to the grounded mast, and not to the balun and then to the television cable. The antenna parameters do not differ for a grounded vertex and an isolated one. Because galvanized mesh does not have rigidity and load-bearing capacity; to maintain its shape, it is necessary to make 2 horizontal crossbars (from a duralumin corner or strip) at the level of the tops of the vibrator. Attach the vibrator mounting posts to these horizontal struts. The technological gap N-M in the center can be varied within small limits depending on the box used, in which the balancer (balun) or antenna amplifier type SWA/PAE/ALN will be hidden. 
A few words for those who consider homemade antennas to be a relic of the “soviet” and “collective farm-garage” culture. Let’s just say that in the civilized world, to which such anonymous people often appeal, home-made antennas are developed and made by astrophysicists (such as the Hoverman antenna) and professors of medicine, and do not sit and wait for an uncle to do it and bring the finished antenna to the market. This is why the world is becoming civilized, guys.
P.S: Information useful for antenna design specialists from yurik82:
There is no ready-made solution for covering the modern UHF range in the works of Kharchenko and Kismereshkin, because At that time, the frequency range used was smaller and there was no need for such antennas. BiQuad Kharchenko with a fixed frame perimeter with full symmetry of the double frame has 4 main degrees of freedom:
In order to select these dimensions optimally (to maximize gain while limiting SWR<2), использовалcя разработанный Николаем Младеновым скрипт Python для движка NEC2:
http://clients.teksavvy.com/~nickm/scripts.html
Using nonlinear programming methods, such a script automatically goes through tens of thousands of combinations of “antenna degrees of freedom.” The result is an antenna model in which the desired properties are maximized.
The final result was also tested in the Ansys HFSS simulator (the results in 4NEC2 and HFSS are completely the same)
https://ypylypenko.livejournal.com/20678.html
The popularity of the Internet among the population is constantly growing. However, many people live in places where the signal is very weak or non-existent. In this regard, the problem of increasing the power and quality of Internet reception becomes very acute. Slow speed takes a lot of time and does not give the desired result. Therefore, an external Kharchenko antenna, designed in the form of a thick copper wire, often comes to the rescue. The connection with a square to each other occurs in places of open corners, where the television cable is connected.
Such an antenna requires precise calculations for digital terrestrial television. To improve directionality, some designs may include a grating or continuous screen made of conductive material. Such a biquad antenna allows you to solve many problems with signal reception and Internet speed. Homemade structures, including various types of Kharchenko antennas, are relatively easy to make and include metal and plastic parts, as well as elements from other materials, connected in different ways. Similar designs can be easily made independently, including the Kharchenko antenna for TV with your own hands.
Currently, many users are looking to increase the speed of their mobile Internet. This problem is especially acute for those who live at a considerable distance from the base station, using the Internet at very low speeds. In such situations, the best way out is a Kharchenko antenna for a 3g modem with your own hands, which is quite easy to make at home.
This frame structure has been known as a UHF antenna since the 60s of the last century. It has a zigzag frame configuration which makes the device very efficient.
The system consists of two square elements. In order to calculate the antenna for a 3g modem at a frequency of 2100 MHz, the size of each side of the square must be 53 mm. The entire design is made in the form of an interlocking structure, which includes two diamond-shaped figures with internal angles of 1200. This is done in order to reduce the internal resistance of the device. The diamonds are connected to each other by soldering. The high-frequency cable is also soldered here.
More accurate data can be obtained using an online calculator for calculating the Kharchenko antenna, into which you just need to enter the necessary initial data.
To increase efficiency, the device can be used in conjunction with a reflector. Usually this part is a metal plate, and the most suitable material for its manufacture is foil PCB. In this case, the antenna involves determining the distance between the receiving device and the reflector. After calculations and procurement of materials, a Kharchenko antenna for the modem can be made with your own hands.
The parts are connected to each other using hot-melt adhesive. You can fix the required distance between elements using any object with the most suitable dimensions. Then the antenna is connected to the device. Since modems do not have connectors for connecting external antennas, they are simply wrapped with wire, which is then connected through a cable to the receiving device. If necessary, a Kharchenko antenna for a 4g modem can be made using the same scheme.
Upon completion of assembly, at the opposite end of the cable that will connect to the modem, you need to assemble a so-called matching device, designed specifically for such devices. For this purpose, copper foil is used, the same as in printed circuit boards. The calculation of the antenna for the 4g modem is the same as in the previous version.
If there is a connector for an external antenna, the cable is connected using a special adapter. After all connections, the antenna for the modem is considered ready for use. Setting up signal reception for 4g is done experimentally by slowly rotating the structure around its axis until the clearest signal is obtained. The quality of the signal is determined by the number of lines on the icon displayed on the computer or mobile phone.
Digital television uses the UHF wavelength range. Therefore, before designing, Kharchenko antennas for DVB t2 should be made in order to maximize signal reception.
The design itself looks quite compact, is made in the classic version from two rhombuses, the result is a zigzag antenna without a reflector. Any conductive material can be used as a base, for example, a copper or aluminum conductor with a diameter of 1-5 mm. Tubes, strips, corners, profiles, etc. are also suitable. Copper wire 3 mm thick is best suited for these purposes. It bends, aligns and solders very easily. Next, it must be manufactured in a certain sequence. The resistance of the television cable should be approximately 50-75 Ohms.
The quality of a digital signal does not depend on distance, as it does in analog television. In this case, when the TV antenna is working normally, the signal enters the TV receiver normally, but if there are malfunctions, then there will be no signal at all. Accordingly, there will be no image. If there is a signal and it is received normally, then the image will be of the same quality on all channels. This factor must be taken into account when performed for digital TV, although individual settings may vary for a particular region.
The Kharchenko television antenna itself is manufactured in a certain sequence:
A remote directional antenna can significantly increase the capabilities of a mobile phone and improve the quality of communication when the subscriber is in a remote area. It is not always possible to find the most suitable option on sale, so the best way out is a Kharchenko antenna for cellular communications, made from scrap materials with your own hands.
The most affordable option is the standard design discussed above. Such an antenna should be sized based on specific operating conditions. All necessary materials are sold at the hardware store. The simplest designs can connect directly to the cable and do not require any special settings.
First of all, you need to stock up on copper wire with a diameter of 2-3 mm. You can take an insulated wire and strip the insulation from it. If connections are to be made without soldering, special F-type antenna connectors and connectors will be required. When you plan to connect two Kharchenko antennas in parallel, you may need a reflector, which can be tin or aluminum. The joints are insulated using heat shrink tubing or electrical tape. For soldering connections you will need a soldering iron.
Copper wire, prepared in advance, is bent and turned into a zigzag frame, representing two diamonds. The sides of each of them are 80 cm long, and the total distance between opposite corners will be 226 cm. Next, the antenna calculator determines the point of connection of these diamonds as the point of connection with the cable. A piece of cable measuring 50 cm is soldered to this point, and an F-type connector is screwed to its opposite end. Next, the main cable of the required length is connected to the connector.
In some cases, calculating the Kharchenko antenna online involves installing a reflector that significantly enhances signal reception in a certain area. The design is the same as the antenna for T2, when the lower end of the frame and the reflector are connected to each other through the cable braid. For this purpose, a 50 mm long bolt is additionally screwed into the reflector, to which the F-type connector is attached using a tie. A cable and a frame located at a distance of over 40 mm are first soldered to this connector. Thus, the Kharchenko antenna for a mobile phone, made independently in the simplest version, is ready for use.
To directly connect the receiving device to a mobile phone, a pigtail is used, which is a special wire. One end of it is connected to the antenna cable, and the other - using a connector to the antenna socket of the phone. In this case, there is no problem with calculating the antenna and no separate settings are required; it is enough just to position the antenna in the most optimal way, focusing on the quality of the received signal. It is recommended to install the mast with the receiving device as close to the house as possible, preferably near a window, in order to minimize the cable length.
The era of digital signals has arrived. All broadcast television companies began to work in a new format. Analog TVs are reaching their end. They are still in working order and are found in almost every family.
In order for older models to successfully complete their service life, and for people to be able to use them when watching digital broadcasting, it is enough to connect the DVB-T set-top box to the TV receiver and pick up the TV wave signals with a special antenna.
Any home craftsman can not buy an antenna in a store, but make it with his own hands from available materials for watching digital TV programs at home or in the country. The two most accessible designs are described in this article.
Any television signal propagates in space from the emitters of the transmitting television tower to the TV antenna by an electromagnetic wave of a sinusoidal shape with a high frequency, measured in megahertz.
When an electromagnetic wave passes through the surface of the receiving beams of the antenna, a voltage V is induced in it. Each half-wave of a sinusoid forms a potential difference with its own sign.
Under the influence of an induced voltage applied to a closed receiving circuit of the input signal with resistance R, an electric current flows in the latter. It is amplified and processed by the digital TV circuit and output to the screen and speakers as image and sound.
For analog models of TV receivers, an intermediate link works between the antenna and the TV - a DVB-T set-top box, which decodes digital information of an electromagnetic wave into a normal form.
In television broadcasting, state standards require electromagnetic waves to be emitted in only two planes:
In this way, transmitters send emitting signals.
And users simply need to rotate the receiving antenna in the desired plane to maximize the power potential.
TV transmitters propagate their signal waves over short distances, limited by the line of sight from the top point of the TV tower emitter. Their range rarely exceeds 60 km.
For such distances, it is enough to provide a small power of the emitted TV signal. But, the strength of the electromagnetic wave at the end of the coverage area should form a normal voltage level at the receiving end.
A small potential difference, measured in fractions of a volt, is induced at the antenna. It creates currents with small amplitudes. This imposes high technical requirements on the installation and quality of manufacturing of all parts of digital reception devices.
The antenna design should be:
The main parameter influencing the quality of the received digital signal, as can be seen from the explanatory first figure, is the length of the electromagnetic wave of radiation. Under it, symmetrical arms of vibrators of various shapes are created, and the overall dimensions of the antenna are determined.
The wavelength λ in centimeters can be easily calculated using a simplified formula: λ=300/F. It is enough just to find the frequency of the received signal F in megahertz.
To do this, we will use a Google search and ask it for a list of regional TV communication points for our area.
As an example, a fragment of a data table for the Vitebsk region is shown with the transmitting center in Ushachi highlighted in red.
Its wave frequency is 626 megahertz, and its polarization type is horizontal. This data is quite sufficient.
We carry out the calculation: 300/626=0.48 m. This is the length of the electromagnetic wave for the antenna being created.
We divide it in half and get 24 cm - the desired half-wave length.
The tension reaches its maximum value in the middle of this section - 12 cm. It is also called amplitude. The whip antenna is made to this size. It is usually expressed by the formula λ/4, where λ is the electromagnetic wavelength.
It will require a piece of coaxial cable with a characteristic impedance of 75 Ohms and a plug for connecting the antenna. I managed to find a ready-made two-meter piece in the old stock.
I cut off the outer shell from the free end with a regular knife. I take the length with a small margin: when setting up it is always easier to bite off a small piece.
Then I remove the shielding layer from this section of the cable.
The work is done. All that remains is to insert the plug socket into the connector on the TV signal set-top box and direct the bare wire of the inner core across the incoming electromagnetic wave, taking into account horizontal polarization.
The antenna should be placed directly on the window sill or secured to the glass, for example, with a piece of tape, or tied to the blind mount. Reflected signals and interference can be shielded with a strip of foil located a short distance from the central core.
Such a design can be done in literally ten minutes and does not require any special material costs. It's worth trying. But, it is capable of working in an area of reliable signal reception. My building is screened by a mountain and a multi-story building. The transmitting television tower is located at a distance of 25 km. Under these conditions, the digital electromagnetic wave is reflected many times and is poorly received. I had to look for another technical solution.
And for you on the topic of this design, I suggest you watch the video by the owner of Edokoff “How to make an antenna for digital TV”
To receive analogue television signals of various wave frequencies, the design of a zigzag broadband antenna, which does not require complex manufacturing, worked well for me before.
I immediately remembered one of their effective varieties - the Kharchenko antenna. I decided to use its design for digital reception. I made the vibrators from a flat copper bar, but it’s quite possible to get by with round wire. This will make it easier to bend and straighten the ends.
Online calculator
Let's use the all-knowing Google search. We write on the command line: “Calculation of the Kharchenko antenna” and press Enter.
We choose any site you like and perform online calculations. I went into the first one that opened. This is what he calculated for me.
I presented all his data with a picture indicating the size of the Kharchenko antenna.
I took the information provided as a basis, but did not accurately maintain all the dimensions. I know from previous practice that the antenna works well in the broadband wavelength range. Therefore, the dimensions of the parts were simply slightly increased. The half-wave of each harmonic of the sine wave of the electromagnetic TV signal will fit into the arm of each vibrator and will be received by it.
Based on the selected data, I made blanks for the antenna.
The connection of the ends of the figure eight busbar is created in the center at the bending stage. I soldered them with a soldering iron.
I created it according to the “Moment” principle, made it with my own hands from old transformers, and has been working for two decades. I even soldered 2.5 square copper wire with it in thirty-degree frost. Works with transistors and microcircuits without burning them out.
In the near future I plan to describe its design in a separate article on the website for those who also want to make it themselves. Follow publications, subscribe to notifications.
I simply soldered the copper core and braid to the metal of the figure eight from different sides in its center.
The cable was tied to a copper bar, bent into a loop in the shape of a semi-square vibrator. This method matches the resistance of the cable and antenna.
In fact, the Kharchenko antenna often works normally without signal shielding, but I decided to show its manufacture. For the base I took a wooden block. I did not paint or varnish: the structure will be used indoors.
In the back side of the block I drilled holes for attaching the screen wires and inserted them, and then wedged them.
The result was a screen for the Kharchenko antenna. In principle, it can be made of a different design: cut from a piece of frontal armor of a tank or cut from food foil - it will work approximately the same.
On the back side of the bar I secured the vibrator structure with a cable.
The antenna is ready. All that remains is to install it on a window to work in vertical polarization.
When a television receiver is located at a great distance from the transmitting generator, the power of its signal gradually weakens. It can be increased by special electronic devices - amplifiers.
You just need to clearly see the difference between the signals received by the antenna, which can be:
In both cases, the amplifier will fulfill its role and increase the power. Moreover, the TV will clearly perceive and display a weakened signal, but with an amplified signal, playback problems will arise.
The waves are designed to eliminate such interference:
They must be measured with an oscilloscope, and the methods of using various designs must be analyzed individually in each specific case. The antenna is not to blame here.
