How to strengthen the Wi-Fi signal with your own hands. Do you have a beer can? DIY antennas 3g antenna from a can

Can antenna for Wi-Fi networks have gained particular popularity for their simplicity and minimum materials for assembly. Simply put, practically out of garbage you get a good directional antenna. Abroad, this antenna is called “Cantenna”. Here is a play on words: antenna - antenna, can - I can, tin can. In general, something like: “We can make an antenna out of a tin can.” Really, can antenna for Wi-Fi, 3G, 4G may be best suited for DIY by an untrained radio amateur.

At CDMA frequencies, the can sizes are far from optimal and a can antenna is not used there.

Getting into the jar, the wave reaches the bottom and is reflected from it. The reflected wave, interacting with the direct wave, forms an interference pattern (standing wave) inside the can. The maximum electric field occurs at a distance λg/4 from the bottom (λg is the wavelength in the waveguide). A quarter-wave pin is installed in this place, receiving th probe connected with a 50-ohm coaxial cable to the adapter. The optimal length of the can itself is 3λg/4. This is not the minimum, but the optimal length.The fact is that the wave is reflected not only from the bottom, but also from the outer cut of the can. This one is re-reflectedThis wave contributes to the interference pattern. With a can length of 3λg/4, 5λg/4, etc., the signal on the pin is maximum, with a can length of 2λg/4, 4λg/4, etc., it is minimal. Those. a jar slightly shorter or longer than 3λg/4 will also work. This must be kept in mind, because when you try to cut some cans, they then fall apart along the seam. But you still need to try to make the jar of optimal length. It needs to be cut a little longer than 3λg/4 and then rolled up the edge.

To determine whether the can is suitable for a Wi-Fi or 3G antenna and calculate the design dimensions, you can useonline calculator on our sa Yes. I also offer a small program for calculating a can antenna for Windows. It’s not difficult to choose a jar; preferably, of course, a perfectly cylindrical one, but, for example, a Nescafe coffee can works well. Having picked up the jar, you need to drill a hole for the connector. It is better to use a connector with a nut. To the horse who solders a pin from a piece of copper wire, screws the connector into the can (you need to make sure that it has electrical contact with the inside of the can, since sometimes it is varnished) and that’s it, the antenna is ready. You just need to make a cord to connect it to the adapter.

Calculation of a can antenna is available in the Android mobile application, available on Google play. You can download it to your mobile device by clicking on the button below or using the QR code. Don't forget to rate the app...

If you have a 3G USB modem and want to boost the signal using such an antenna, you can simply insert the modem inside the can. This eliminates the problem of connecting the antenna to such a modem. A hole is cut for the modem at the same distance λg/4 from the bottom, the edges are rolled so that there are no sharp edges. This antenna option can, of course, be used next to a laptop, as in the photo at the beginning of the article. You just need to keep in mind that for some modems (for example, 3G modems Huawei E171, E173), its internal antenna is located not at the end, but closer to the USB connector, and this version of the can antenna will not work with such modems.

If you place your homemade antenna from a tin can somewhere on a mast or just outdoors, then the finished antenna must be sealed from the weather by covering it with a plastic lid. Only the cover needs to be checked to see if it absorbs radio waves. The easiest way to do this is using a microwave. Since you can’t turn it on empty, put at least a glass of water in there, put the lid on and turn it on. If the lid does not heat up in the end, then it does not absorb radio waves and is suitable for our purpose. It’s a good idea to drill a 2 mm hole behind the connector so that condensation, which will inevitably collect in the jar, drains through it. However, any tin can is short-lived and rusts over time, rust weakens the signal, so if you notice that the connection is deteriorating, it’s time to look for a new can and redo the antenna. In general, using this antenna as a stationary one on a mast is not the best option. But as a portable one, that’s another matter.

The can antenna can be slightly adjusted. You can tilt the pin relative to the bottom of the jar, changing the conditions of coordination with the cable and the position of the pin relative to the antinode of the field in the jar. By rotating the antenna around its axis, you can change its polarization. In practice, a gain of 4-6 dBi can be achieved from such an antenna.

Comments

3G-Aerial admin 06/22/2015 20:30

I quote Sergey:

Do I understand correctly that lengthening the can entails more difficult adjustments to the operator’s BS? Apparently a bell can make this task easier?

No. Any increase in gain is associated with a narrowing of the main lobe and, accordingly, with the complication of tuning. The satellite dish has a very large “bell” and is nevertheless quite difficult to tune.

Many people in the modern world use the mobile Internet - with the help of it a person can communicate remotely, receive information and even work. But the provider does not always provide users with a stable connection speed due to the characteristics of communication reception, which may be limited by terrain features, a large distance to the transmitter, and other factors.

A homemade antenna for a 3g modem will help you improve the speed and range of signal reception. We offer you several instructions on how to make an antenna for a 3G modem with your own hands.

Kharchenko's method

We recently wrote how to make an antenna for television reception with your own hands. But did you know that you can make a homemade antenna for a 3G modem in a similar way?

We will need:

• Copper wire or wire, you will need a section of about 30 centimeters;
• Coaxial cable with a resistance of 50 or 75 Ohms;
• A piece of foil or DVD as a reflector;
• Tools: knife, soldering iron, pliers, glue, ruler and pencil;
• Plastic bottle cap to separate the antenna from the reflector.

Production of biquadrat Kharchenko

In photographs of homemade antennas for 3G modems you can see its approximate appearance. First, you need to make markings on the copper wire with a pencil: the length of the outer side of each square should be approximately 35-36 mm.

Carefully bend the wire along the markings, helping yourself with pliers. You should get a symmetrical design of two squares touching at the corners. Remove the remaining pieces of wire.

Make a hole in the cover and insert the end of the cable into it. Separate the cable, exposing the inner conductor and shield for soldering.

Next, you should solder the antenna to the cable and connect it to the modem. Soldering proceeds as follows: solder the central core to the middle of the antenna on one side, and the screen on the other. Then move the cover towards the antenna; you can further strengthen and insulate the structure with glue or sealant.

Insert the reflector disk into the wire through the hole, move it towards the antenna and glue it to the cover. Solder the connector to the cable on the other side for connecting to the modem. Connect the antenna to the modem. Enjoy the results of your work!

Double ring antenna

The next method of creating a homemade antenna is more difficult to implement, but gives a greater effect. To complete it you will need:

• Copper wire or wire;
• Reflector - a flat long tin can, a piece of foil, etc.;
• Coaxial cable with a resistance of 75 Ohms;
• A short metal tube into which a cable can be threaded;
• Connector for connecting the antenna to the modem;
• Tools: soldering iron, knife, ruler and pencil.

Detailed manufacturing instructions:

• Look on the Internet for a Bi-Loop antenna diagram for a 3g modem - on it you will see a design similar to the Kharchenko antenna, but in the form of two rings;
• Make markings on the wire with a pencil: for waves with a length of 2050 MHz, the length of each ring should be approximately 146 mm;
• Carefully bend the wire into a double ring. You can also make two rings with gaps approximately 3mm long and solder them end to end, leaving the gaps open;
• Make a reflector. Minimum dimensions: height - 120 mm, width - 170 mm. Any metal panel will do; you can use foil or tin from a tin can if you have available materials;
• Make a hole in the middle of the reflector through which to insert a metal tube - from the side connecting to the antenna, the length of the tube should be approximately 18 mm! Solder the tube to the reflector on the other side;
• Separate the cable with a knife: the screen should be soldered and the conductor should be slightly exposed;
• Pass the cable into the tube and solder the antenna to it: the upper part should be soldered to the conductor, and the lower part to the copper tube;
• Solder the tube and cable braid;
• Additionally, to strengthen the signal, you can use a satellite dish by installing a ready-made antenna on the bracket;
• The other end of the cable should be connected to the modem connector using a soldering iron;
• Connect the antenna to the modem. Ready!

Now you know several ways to make an antenna for a 3G modem with your own hands. The above methods should help you solve problems with low Internet connection speed.

Photo of antennas for 3g modem

Mobile Internet is still inferior to home Internet in speed. Subscribers are not always in a stable coverage area. If the signal is weak, page loading speed will be slow. One solution is an external antenna for a USB modem. You can either buy it or make it yourself from available materials.

In what cases is an antenna needed for a modem?

The antenna will improve the mobile Internet if there are two or even one division on the signal icon. The external antenna components will pick up the signal where the built-in antenna cannot. If there is no signal at all, there is a chance that even an external antenna will be powerless in your case.

Many modems have a connector on the side for connecting a cable from an external antenna

If the problem is only in speed - there are a lot of bars, most likely the reason is that the operator's base station is overloaded with requests from subscribers. Even if you install an antenna, the speed will not increase. In this case, it is recommended to change the operator or try to point the antenna at another company tower.

What types of 3G/4G antennas are there?

Antennas (both purchased and homemade) are divided into several types depending on several indicators. If we talk about the installation method, there are indoor or outdoor antennas. The latter are more effective because they work in open space, where there is less interference. They are suitable for those subscribers who live far from the tower.

Indoor antennas are not as effective as outdoor antennas

Based on the receiving signal, antennas are divided into broadband and narrowband. The first ones are more functional - they are capable of receiving 2G and 3G signals when, for example, 4G does not work.

Antennas are also divided into directional, omnidirectional and sectoral. The last two types are capable of catching signals from several towers at once. There are also conventional devices and MIMO antennas - advanced equipment with two antennas at once, which receive the signal separately from each other, but transmit the signal to the modem simultaneously. They can increase speed up to 100 Mbit/s.

The MIMO antenna essentially has two receivers, hence its effectiveness

Depending on the presence of an amplifier in the antenna, devices are divided into active and passive. Passive ones, where there is no amplifier, do not improve the mobile network signal as much as active ones, but they do not need to be connected to an outlet (the amplifier is powered by an electrical network).

Making an antenna from a tin can

The advantage of this homemade antenna is its accessibility. In every home you can find a loose tin can - be it for coffee or carbonated drinks. It is better for it to be cylindrical - without corners. The jar will be a kind of “hearing aid” for the waves. They will reach the bottom and be reflected from it. As a result, a standing wave will form in the jar.

What needs to be done with the can to make an antenna from it:

The disadvantage of this method is that it is not suitable for all cases, for example, if you live on the first or second floor and your house is located far from the tower. It can help you if the signal problems are not too serious. Thus, the antenna is easy to manufacture, but not as effective as, for example, the Kharchenko antenna.

A more complex variation of the can antenna - with a metal connector inside and a wire that extends from it:

Wire antenna

Another primitive way to strengthen a fading mobile network signal is copper wire. It needs to be wrapped around the bottom of the modem, where the internal antenna is located. About 20 - 30 cm of the wire should remain free. We bend this free piece - it should be perpendicular to the modem, that is, vertical. We place the modem with a homemade antenna on the window and connect it to the PC using an extension cord.

Make a few turns around the modem and straighten the cable vertically

An extension cord can be purchased directly with the amplifier - this will also help improve performance.

Kharchenko antenna (biquadrat): simple step-by-step instructions

The scientist Kharchenko proposed this model of a loop antenna in 1961. It was used as a receiver for TV broadcasts. The antenna is very effective - it acts as both a receiver and an amplifier. It is broadband, capable of increasing the signal power to 3 - 4 dB in the absence of a reflector and up to 8 - 9 dB with a reflector (a metal panel that reflects the signal). It doesn't matter whether it's 3G or 4G.

The downside is that it is difficult to manufacture compared to previous homemade antennas. However, with the proper desire, everyone can cope with its creation:

1. First, make a “figure eight” from a monolithic wire with a cross section of 4 mm 2. The squares should be as uniform as possible. There must be clear symmetry. To achieve this, mark the wire with a marker before bending. Then place the pliers on the wire markings. Now you need to bend the wire at an angle of 90 degrees. Use a square to get the exact angle.

   Make a symmetrical figure eight from copper wire

2. Take an aluminum plate - thickness 22 mm. Total area - 140 x 140 mm. The plate will be a reflector (reflector). Make a hole in the center of the plate (drill).
3. Secure the figure eight directly in the center of the reflector at a distance of 3.6 cm. The panel and the wire should not touch.

   Secure the antenna with wooden sticks on the sides

4. Drill holes in the reflector for the clamps, put the structure on the bracket (take it from the satellite dish). Now you need to solder the cable, passing it through the hole in the plate in advance.

   Run a cable from the antenna to the modem

5. If the modem has an antenna connector, connect the cable to it using an adapter.
6. If there is no connector, take some copper foil. Make a cap according to the dimensions of the modem. Attach the cable to the cap (needs to be soldered) and put it on the device.

   If there is no antenna connector, use a copper plate to secure the wire to the modem

7. After connecting the antenna, adjust the signal - rotate it until you get the maximum result in the form of several divisions. They are displayed in the proprietary program of the device or your provider, which is downloaded and installed on the computer to set up the connection. Try placing the antenna at different angles, such as 45° or 70°.

Video: how to make a Kharchenko antenna

Other homemade antenna options

Ideas for homemade antennas could be the following:

1. Colander 4G. Everyone has a simple aluminum colander in their home. You need to fix the USB extension cord on the handle of the cookware. Connect a modem to it - it should ultimately be within the circle of the bowl. We direct the colander to the base station and catch the signal.

   You can strengthen the signal using a regular colander.

2. 3G/4G satellite dish. If you have an old satellite dish, use it. The signal will be amplified significantly, since the antenna will be outdoor. Remove the converter from the boom. Secure the modem at this location. Naturally, you will need a USB extension cable - carefully stretch it to the modem and connect it. Now point the dish at the operator tower. To adjust, you will need to rotate the plate slowly to achieve maximum effect.

   Click on "Measure" on the website

   If you need a simple antenna that does not require special skills or knowledge to make, make a wire or can antenna. You can also take the option with a colander or an old satellite dish. For more experienced people, more complex methods are suitable - the Kharchenko antenna or the “Double Ring”.

Andrey Baryshev, Vyborg

A considerable number of wireless Internet users have to deal with the problem of low connection speed. This problem is especially relevant for subscribers living outside large populated areas and at great distances from the nearest cell phone towers. But even in cities with dense buildings, it may happen that receiving a direct cellular signal is impossible; you have to be content with using a reflected signal, weakened several times. In all these cases, the use of additional remote antennas can be quite effective, the proposed designs of which differ in the principle of their construction, complexity and declared radio technical parameters.

In my case, the problem was the extremely low speed of the Internet connection due to the great distance from the tower (10 km in a straight line). In addition, receiving a direct signal was impossible due to the five-story panel buildings located in front. For this reason, the 3G signal was practically not detected by the modem, and it was possible to work only in GPRS mode (an MTS MF192+ modem was used).

Numerous ways to increase the level of the received signal were considered, including those found on sites on the Internet. Having analyzed various antenna designs and reviews of their performance, it was possible to conclude that either variants of directional antennas of the “wave channel” type, or reflector dishes, in the focus of which the modem itself is located, work most effectively. But the manufacture of such antennas requires precise and complex calculations and rather specific materials, so making them at home is not easy. And the options of taking the modem itself “outside” (outside the window, onto the roof, etc.) were immediately eliminated due to the need to use a USB extension cable more than 15 m long. Even with a much smaller size of such an extension cable, the modem may stop working normally due to attenuation signal and supply voltage drop. In addition, the modem is, in principle, not intended for operation in outdoor conditions with significant changes in temperature and humidity. Therefore, only indoor directional antennas were considered, the best of which, according to numerous reviews, were the “zigzag Kharchenko” or “bi-square” antennas.

But, despite its apparent simplicity, many options for manufacturing such an antenna can also be found, and completely different sizes of the component elements and methods of arranging the entire structure are often indicated. To compare all the options in practice, several such antennas with different sizes and in different “modifications” were manufactured and tested in practice, including versions of the antenna with four and six squares (double and triple “bi-square”, respectively). At the same time, my designs made it possible to quickly change the configuration and dimensions of various components.

It should be said that in my case, the use of double and triple versions of the “bi-square” showed practically no advantage over the usual, simple version of this antenna. Therefore, in the future, detailed calculations and features of manufacturing a “classical” antenna will be considered.

Antenna calculation

To accurately calculate the dimensions of the antenna you will not need any special theoretical knowledge or any programs.

The perimeter of this type of antenna frame must be equal to the wavelength of the received radio signal. In our case, the wavelength can be calculated by knowing the frequency of the 3G signal, which is 2100 MHz. To do this, you need to divide the speed of propagation of radio waves (300,000 km/s) by the frequency, resulting in the length of the frame equal to

300,000/2,100,000 = 0.143 m.

Since the frame is square in shape, you should divide its total length by 4, resulting in the length of each side of the square equal to 35.75 mm. In many sources you can find completely different side sizes - from 27 to 53 mm. Obviously, such antennas are designed for a different range, for example GSM or Wi-Fi, whose operating frequencies are, respectively, lower or higher than in our case.

The gain of this antenna is approximately 6 dB. When making it, all dimensions must be observed as accurately as possible; the quality of work greatly depends on the quality of workmanship. It should be noted that any antenna without an amplifier does not amplify the signal as such, but distinguishes it from the background of other signals and various interference (if the antenna is not broadband). Due to this, we receive the signal we need, the level of which is much higher than the level of interference. Therefore, exact adherence to the dimensions of the antenna is important, because in this way we will get precise tuning to the desired operating frequency!

To increase the gain to 9 dB, you can use a reflector. This can be a metal plate, a fine mesh or even foil glued to plywood or thick cardboard, with dimensions 10-15% larger than the area of ​​the “canvas” of the antenna itself. In this case, the reflector will have dimensions of 125 × 75 mm.

Manufacturing

Thus, an antenna for receiving 3G signals (without a reflector) will look like shown in Figure 1.

Picture 1.

To make it, we need a copper wire with a cross-section of at least 4 mm 2 (you can use, for example, a “core” from a VVG or NUM brand electric power cable). The perimeter of each square is equal to the wavelength - 143 mm. Since the antenna consists of two squares, you will need a piece of wire 2 × 143 mm long = 286 mm.

We divide the wire into 8 equal sections and bend them at an angle of 90° in these places, and solder the free ends together to form a closed loop (Figures 2 and 3):

The reflector should be mounted behind the antenna “squares”, and the distance to the reflector is also of great importance, as it affects the input impedance and matching with the connecting cable. Theoretically, this distance should be ¼ wavelength, which in our case is 143/4 = 35.75 mm. But my antenna, for example, works better at a distance of 18 mm, and this turns out to be 1/8 of the wavelength. Therefore, it is better to make the distance to the reflector adjustable and experiment with it during the setup process. To do this, we take a piece of copper tube of a suitable diameter (our connecting cable should go there), for example, from a telescopic antenna for receivers/TVs. Give it the shape shown in Figure 4.

We drill a hole in the center of the reflector plate so that this tube fits tightly there. It should not dangle freely, then it can not be soldered to the reflector and can be moved during adjustment, adjusting the distance to the antenna plane. We solder our frame of two squares to this tube, as shown in Figure 5).

We pass the cable through the tube and solder its central core to the inner corner of the frame opposite the tube hole, and the braided cable screen to the tube on the opposite side of the reflector (Figures 6 and 7).

After final adjustment of the antenna, the tube can be soldered to the reflector. The plane of the antenna must be strictly parallel to the plane of the reflector, because even a slight misalignment and non-parallelism can greatly reduce the signal level. To ensure structural rigidity, pads made of PCB or other good insulator can be glued between the reflector and the extreme corners of the frame.

Connection to modem

If your modem does not have a special connector for connecting an external antenna, then you will have to make a kind of adapter that is worn externally and transmits the signal to the modem’s built-in antenna through re-radiation. In the simplest case, you can simply tightly wrap the modem (at the location of its internal antenna) with several turns of the central core of the connecting cable, as shown in Figure 8.

The number of turns, usually 2...5, is selected when tuning to the maximum received signal. These turns should then be secured to the modem with electrical tape. And you can make the design more complicated, more convenient and efficient. This adapter option is shown in Figure 9.

Structurally, it is a ring that tightly fits the modem body at the location of its internal antenna. The ring can be made from a strip of copper foil 45 mm wide, the ends of which must be soldered together. The central core of the RF connecting cable is soldered to this ring. From another strip of the same foil, but with dimensions of 25 × 75 mm, a half ring is bent, as shown in Figure 9, and the cable braid-screen is soldered to it. There should be no electrical contact between the ring and the half-ring. By adjusting the position of the semi-ring and its angle of inclination relative to the modem, you need to achieve the maximum level of the received signal. The dimensions of such an adapter were not calculated theoretically, but were selected through experiments. For modems of different types and models, the location of the built-in antenna inside the case may also be different (in the area of ​​the USB connector or at the other end). This should be taken into account when placing the adapter on the body of your modem!

HF connecting cable

A little about the types and brands of cable. In addition to quality indicators, the cable can have different impedance - 50 or 75 Ohms, which must be taken into account when choosing it. Wireless modems typically have a resistance of 75 ohms. Therefore, it is better, of course, to use a 75 ohm cable. Judging by numerous recommendations, it is better to use cables of the 10D-FB, 8D-FB, 5D-FB brands (in descending order of quality) due to low signal attenuation rates. Cables of the RG-6 and RG-8X brands perform worse. Therefore, especially with a cable length of more than 5 m, choose a higher quality option, otherwise you may lose all the “gain” that you get from the antenna!

Antenna setup

With the antenna positioned so that it points toward the nearest cell tower (preferably near or opposite a window), adjust the position of the antenna and the distance between it and the reflector plate by moving the handset. You need to navigate by the signal level, and for this it is better to use special programs, for example the “MDMA” program (can be downloaded on the Internet), where there is a signal level scale in decibels. This program does not work with all modems, but there are others similar to it that show the signal level in decibels (signal-to-noise ratio). You can also navigate in the standard connection program for your modem by the signal level of the antenna icon, but this is not very convenient, because there, firstly, there is a somewhat delayed reaction to a change in the signal (up to 10 - 20 s), and secondly secondly, it will not be entirely correct. Because it is the signal-to-noise ratio that is important, and not the signal level as a whole.

In my case, the antenna scale indicator of the “native” connection manager increased slightly after connecting and configuring the antenna, by only 2 - 3 divisions. However, the speed of the Internet connection has increased very noticeably. The download speed increased from 0.5 Mb/s to 3...4 Mb/s during the daytime, and even more at night. Without such an antenna, as mentioned earlier, receiving a 3G signal was generally impossible.

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Sometimes it happens that the Wi-Fi router is located far from the computer and the Internet speed drops significantly or even disappears, thanks to this life hack we will significantly increase the range of Wi-Fi and 3G modems. To do this, we will make a Wi-Fi antenna from a coffee can with our own hands.

So, we will need:

• Coffee tin
• Antenna socket
• Drill
• Soldering iron
• A piece of copper wire
• TV cable

To make a can Wi-Fi antenna with your own hands, you first need to find a coffee can. Now we need to make a simple calculation of our future antenna using an online calculator. Here is a standard version of the can drawing:

In our case, for a coffee can the following was obtained: D (can diameter) = 100 mm, Lo (wavelength) = 143 mm, Lo/4 = 36 mm, Lg (wavelength) = 261 mm, Lg/4 = 65 mm. A hole is made at a distance of Lg/4 from the bottom of the can and a standard antenna socket is fixed in it with a waveguide of length Lo/4 made of 2 mm copper wire soldered to it.

Then connect the television cable with the appropriate braided connectors and the antenna adapter to the modem.

It may also turn out that your 3G modem does not have a socket for connecting an antenna. In this case, there are 3 ways: you can disassemble the modem case, find a contact for connecting an external antenna and solder the middle contact of the cable to this contact and the braid to the negative contact of the board. But for this you need to have knowledge in electronics in order to solder everything correctly and not end up burning anything if something is not soldered correctly. But there is also a second, simpler way. You need to make a hole in the coffee can, the size of the modem, so that it fits tightly into it. Well, with this method you will need to use a USB extension cable so that the antenna can be conveniently hung closer to the window.

There is also a 2nd method, you can try to wind the middle core of the cable with three or four turns onto the modem, before stripping part of the cable from the braid and insulation.

In these simple ways you can strengthen the signal of WI-Fi and 3G networks using a homemade can WI-Fi antenna.