Another homemade product for those who are bored at home
I needed a couple of antennas for digital, in places with “not the best reception”... I went shopping (this was before self-isolation
- if it’s relatively budget-friendly, then it’s complete G. The more expensive one looks decent, but how it works is questionable.
I decided to make something homemade. It was somehow awkward to “twist” an antenna from a piece of cable (although rumor has it it works) - I wanted something simple, but more decent and advanced
In fact, the one I made is not radically more complicated, but somehow more “solid” or something. And the results of its testing were very encouraging, so I decided to sketch out a short description of what and how, in case someone else finds it useful 
... even if my street cats have a “normal” antenna on their house, what can you do without an antenna?!
The wire is not all finished yet, now we’ll assemble something!
In the places described, I previously used home-made broadband log-periodic antennas, probably since the “beginning of perestroika.” They worked well in analog and not only on UHF, but “for some reason, digital was too tough for them.” I didn’t really delve into the essence of the reasons, I removed them and began to think about what to replace them with. Here is one of them, waiting for a place in the trash
A little history
In the early 60s of the last century, our compatriot Kharchenko K.P. developed a simple flat zigzag antenna with good characteristics.
Copyright certificate No. 138277 for an invention called “Band directional antenna” was issued to Konstantin Pavlovich Kharchenko in 1961 (according to his application dated June 16, 1960). In the same year, materials were published in the magazine “Radio” for repetition by radio amateurs.
The antenna is not critical to materials and dimensions during manufacturing, has a simple good match with the reduction cable, and it successfully combines multiple elements of a common-mode antenna array with a single feed point.
Theory and calculations
The described antenna, in theory, has a horizontal “figure-of-eight” radiation pattern and a relatively high gain, which can be further increased by using a reflector/reflector.
To obtain maximum gain on all channels, it is necessary to make an antenna approximately in the middle of the range between the multiplexes used.
Finding (for calculations) the frequencies of multiplexes used in your region is easy,
for example, a request like “dvb-t2 channel frequencies” + “Krasnodar”
I found something like this:
The middle, between “my” two multiplexes, is 700 MHz - we will calculate the antenna at this frequency.
As a basis for calculating the dimensions of the antenna, we take the drawing of its author
Calculate the wavelength: λ = 300 / f [m]
300/700 = 0.428m, approximately 43cm length of each side of the rhombus
λ/4
=43/4= 10.75
The total length of the material we need (11cm*8=88cm) is less than a meter. The distance between the reduction contacts, where we will solder the cable, is 10-12mm (the standard value for this antenna for frequencies below 900 MHz).
I will make a simple antenna, without a reflector, however, to further increase the gain of this antenna, it is quite possible to install it behind it
for example, from a metal mesh/grill, foil material or simply a metal plate. Its dimensions should be approximately 20 percent larger than the dimensions of the antenna and it should be located at a distance of ƛmax/7. For my case: wavelength (channel 39) 300/618, it turns out...49/7= that is, about 7cm
For those who are too lazy to do the calculations themselves
— you can use an online calculator, the results will differ only slightly from those I received. Here, for example, this one - here you immediately enter the frequencies of two multiplexes and get the dimensions of the antenna (without a reflector) Or another option, with a reflector - I really want to note that in the second option a slightly different calculation option is used, different from the author’s. An antenna with angles other than 90° is assumed and the reflector distance is calculated as λ/8
To make the antenna sheet, it is recommended to use aluminum or copper (copper is easily soldered) with a diameter of 3 mm and higher - the larger the diameter, the more broadband the antenna is. You can use tubes; the thickness of the walls is not important, since only the surface of the material is used (in fact, you can wrap any dielectric with foil to obtain the required material). However, in my opinion, the easiest way is to buy a meter of large-gauge copper wire at an electrical supply store.
Super antenna for digital TV, or another deception?
Hi all!
The author of this site, Vitaly Lebakh, is in touch. And what prompted me to write this article? One might say, the desire to warn its readers about the deception that is actively promoting in the wake of the spread of digital television. Outrage at the impudence of some sellers who sell people goods that are not worth their money, knowingly deceiving and misleading.
To be honest, after watching this ad I thought, “Come on! No one will fall for this” - But I was wrong, however, it’s understandable, people invest a lot of money in advertising. Before this, they conduct various tests, select texts and slogans, in general, they do everything so that an uninformed person would say “Uh-huh-I WANT” and run to lay out his money.
Key to free TV
At first, advertising fell off the TV screens.
By the way, it looks something like this - it’s not necessarily the antenna that is advertised, there are many of them like it. But the antenna concept is exactly this: a Ring, a Mustache (completely unnecessary for DTV) and an amplifier power regulator.
The store on the couch offered a certain antenna positioning it as “The Key to Free TV” - and there is some truth in this, indeed Digital Terrestrial Television is absolutely free. As many as 20 television channels and 3 radio stations.
And THAT'S ALL, guys THAT'S ALL! Twenty and three - Not a hundred or two hundred, and for the majority of the audience these 20 are enough. And in some places there aren’t even 20 yet; only 10 digital channels are broadcast.
Here you can find out where the nearest towers are and how many DTV channels they broadcast.
“Perhaps in the future, when radio frequencies are freed up, due to the large-scale introduction of DTV, there will be an opportunity for another package of free channels”
But why shout that with this miracle antenna it is possible to watch more than a hundred digital channels?
Why put this antenna in such a way that all you need to do is purchase it and that’s it! And numerous digital channels will appear on your TV screens. And the fact that most TVs do not have a DVB-T2 tuner and this antenna will be useless, not a word.
Since I deal with television, antennas and the like, people began to contact me asking for the opportunity to purchase this wonderful antenna! I explain to them that this is all a hoax, there is no need to buy an antenna for 2999 rubles.
But the power of advertising is great! And even my authority in the field of antennas is not always able to destroy it.
— Since I couldn’t buy it from you, I’ll buy it directly from the TV store!
Time passes! They come - “She doesn’t catch anything - I called them, they said send her back to us, we will return the money.” Well, at least this way. Although I have doubts about this too. If they start accepting all returns……. Well, you understand!
Was it worth the bother! When an antenna that actually works costs three or even four times less.
Well, yes, they don’t play it on TV, it’s simply offered by a person who installs and configures antennas, this is not our level!
Why am I so obsessed with this antenna? A normal antenna will even work in conditions of a good signal, and since the digital TV signal in many regions is already high, and this trend will develop, it will work for many. This is what sellers are counting on.
Well, the fact is that its real price does not exceed 1200 rubles (and this is the retail price for such an antenna).
Online sellers also got involved with no less cynicism. I came across one such site.
I propose to consider their proposal in more detail, so to speak in pictures.
It’s true that there are no ripples, a clear and stable image! Digital television is capable of this. But not always with the antenna they offer. The fact that there are more than 100 channels is an outright lie! 20 channels is all, well, only in some regions there is a little more due to non-state TV channels, or for example in cities bordering Ukraine, you can catch Ukrainian digital TV channels.
The phrase “Ideal for plasma TVs” is absolutely killing.
The fact is that when plasma was produced, the DVB-T2 format did not exist at all, and therefore a plasma TV without a set-top box will not receive digital data. So it's not ideal. But even this is not all.
Just a few days ago, I was repairing a SAMSUNG plasma TV with a diagonal of 50 inches. The infection consumes 450 watts! So, this TV, when connecting the set-top box via the HDMI input, reports “Unavailable format.” It turned out that the set-top box was switched to 1080 P image resolution mode, and the TV was only capable of reproducing 720 P. So there is no talk of any HD using plasma! Outdated technology you understand!
Antenna assembly
Let's remove the insulation from a piece of wire one meter long.
I got a wire with a diameter of 4.5mm
The tools you will need are a vice and a hammer. Measure approximately 11cm each and bend at an angle of 90°
The end result is to get such a “geometric” figure
We cut off the excess and solder the ends. It should look something like this...
Solder the cable as shown in the photo.
We lay the cable along one side of the square and secure it with clamps. This arrangement of the cable is necessary for its coordination (there are different opinions, not everyone agrees with this statement).
When using a reflector, the antenna sheet at the extreme points of the squares can also be secured using metal stands, for example, soldered onto the remains of the same copper wire - there are points with zero potential (highlighted in green). In other places, fastening is allowed only through a dielectric.
Tests
And finally, a performance check and a rough
assessment of the quality of the resulting antenna.
In fact, everything is simple with the test - turn it on, it works! And to evaluate whether the game was “worth the candle,” let’s compare the parameters of the received signal from the manufactured antenna with the one I’m already using at the dacha, with a declared gain of 11dBi
The antenna is installed in the attic of a country house, at a distance of approximately 16 km from the tower.
Signal level: factory stationary antenna on the left / homemade on the right
At first glance, the difference is only 1% (95 versus 94) - but this is not a completely correct comparison, since my external antenna is connected through a splitter, which further weakens the signal.
How to choose an indoor antenna for your TV
Let's briefly look at what parameters to pay attention to when choosing an antenna for indoor use:
- What broadcasting standards and bands does it work with
? There are models designed for VHF. These are 2-meter waves of increased range, which are well caught outside the city. Others only work in UHF. These are 80-centimeter waves, and their range is much shorter - it is advisable to be within the city. In addition to analogue broadcasting, some models are capable of capturing open digital channels. - The presence of a built-in amplifier and its power.
If the TV is located far from a tower or even outside the city, then an amplifier is needed. Its power ranges from 10 to 50 dB. The higher the number, the better. - Length of cable to TV
. A cable is included to transmit the electrical signal to the TV. Its length varies from 1 to 3 m. If the device does not receive reception near the TV, you will have to move it around the room. It is convenient to do this with a long wire, since you do not need to rearrange the TV itself. - Installation method.
Some devices are hung on the wall
Well, you will need to drill a hole in a concrete slab or brickwork. Others are installed on the windowsill or the TV itself, if its surface allows it.
Assessing the performance of the antenna
Let's try to make a more correct comparison by connecting through the splitter input.
Well, in addition, for clarity, let’s add the number of participants List of antennas taking part in the comparison:
1. External antenna Funke BM 4551 external long-range,
declared gain, from some sources (bought at Yulmart), up to 16dB
2. There is an old UHF loop antenna, from TV Electronica 313d, I must say, despite its simplicity, it’s a very good antenna, that’s why it’s been preserved
3. I went to the store and bought for comparison in the review one of the cheapest, such as a symmetrical vibrator (100% the most purchased by pensioners, due to the low price).
I will carry out all “measurements” at one point, located as close as possible to the external antenna - its location was experimentally selected based on the maximum signal, so we can say that the conditions are approximately the same
So, we have already seen the signal level from the external antenna at 95% (at the time of current measurements it showed 94%), we take it as a standard. All comparisons are made by connecting antennas to the input on the splitter, to which an external antenna is usually connected.
Loop antenna, from Electronics 82% on 39 multiplex and 66% on 60
Budget with “horns” - 62%/38% (on the verge of losing the broadcast)
Double square - 92% on both multiplexes, about a couple of percent less than the external one
Out of curiosity, I decided to check the work of the reflector, which is easy to make from any metal mesh, plate or even foil... It REALLY works noticeably! The level rose to 96%!, which is even higher than the stationary one, with a declared gain of 11dB.
The most interesting thing is the object that I used as a reflector!
There was no foil in the house; the only thing available with a metal surface of the required size was... a laptop cover (I have a metal case). But the main thing is the result! It’s clear that I’m not going to “tie” the laptop to the antenna, and its amplification is enough for me without a reflector
Antenna for digital TV
I also have 10 programs twice, the first from the 1st to the 11th, the second from the 11th to the 22nd there is no signal, I called the antenna and he calmed down by the evening they will turn it on for prevention. And they really turned it on in the evening, the quality is super. As for Three Colors, they are also extortionists, the quality is below par and they install updates every six months and after a year and a half of operation it stopped working completely. I call and they tell me your modem is outdated and you need to buy a new one, you hand over the old one and pay extra for a new one. I went and the old one was priced at 500 rubles and for the new one I have to pay an extra 8000 rubles, I turned around and left and have no desire to watch them anymore.
In my life I had to resolve the problems of three Tricolor users.
Office of rare eccentrics!!! Just for you, I pulled out angry manuscripts from the anals for private use))) Yes, the moderators will forgive me for the free style, but you can’t erase the words from the song! I lived quietly without sadness, only until those terrible days, How the boys drove up, The wonderful “Tricolor”. We attached the antenna, turned it to reception, adjusted the system, that's it, joy came to the house! But we didn’t enjoy it for long, Apparently the time for happiness has passed - Hop, the channels are lost, Everything is new, press “ok”! Just the beginning of patience, moving away from the settings - “Perform the update” The system tells me. At the appointed hour, turn it off, And then turn it on again, Then go there... Do I need that love??? What the hell? What gag? Do you need to update? My dear father himself would never have missed it. Yes, and I have such a hat, Dancing with a tambourine by the fire. Honestly, if it weren’t for dad, I would have taken the heat to the bucket. We survived this matter and earned a little money. But the song wasn’t sung for long, the block in the antenna burned out. Changed it, the good won’t go out, Air is pouring into the house again. But again a disaster struck, the Tuner left for a better world! I took it to the guys to see what to say with it. They say the board is covered, Apparently there was a thunderstorm. Three pieces of repair board. If I had known, I would have definitely drowned him. Well, since the guys did it. Then he put it in place. Here it is especially necessary to say about the receiver paddock. You really can’t understand if the bastard is dead or not turned on! What the light behind the button looks like, Leshy himself can’t figure it out. With this damn box, Bata is clearly unlucky. And then it happened to pay, Go figure it out again, What goes where, pray tell, Where can I find that ID. I found it, threw in the bucks, They walked for a long time to the enemy’s yard, And then for about eight hours, the Tricolor was doubled. I worked, I fooled around, Apparently I gave everything I could, And again (and I didn’t cry) I died quietly at night! Well, to hell with it - my dad said, Get wet, I'm a fool. Wasting time on a parasha, It hurts honor to the buoy! Peace has returned to my soul, I forgot the lesson of fate, But I broke the idyll, I got a call from a neighbor. So and so, save Seryoga, I will never cope on my own. The tricolor is a little dull, there's a problem with the update. You can’t refuse a person, alone with trouble. You will have to climb into the river again with very muddy water. And now the mother-in-law has a waste, Paid for the Tricolor. It's been a day since the payment went through, it still doesn't work! Again I poke the remote control in the snout of this wonderful crap. What kind of idiots say, they cast a shadow on the fence. Is it difficult for bastards to do a reception block without beauty? So that you no longer need to touch it every time! Update, check firmware, get into his brain with the remote control. So that ordinary people would not be very sad later. It’s very difficult for moms and dads to understand progress, so that they don’t wait for the night. That the picture will come to life. I don't give a damn about him, by the way, I wouldn't take it for nothing. Because it’s very strong, and I really gave it a fuck!!!
Conclusion:
I can confidently recommend repeating it!
Simple, “cheap and tasty”... One of the simplest, indoor antenna mounts... with ordinary suction cups - if you’re lucky with the direction to the television center
The next antenna "recommended for repetition" is... log periodic
“Crazy hands” were with you. Good luck and good mood to everyone! ☕
