How to make an external antenna for a smartphone. How to strengthen the cellular signal on the phone with your own hands. Connecting a mobile to an external antenna

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Dense urban development, terrain, power lines and remoteness from transmission towers greatly affect the quality of signal reception, which can disappear at the most inopportune moment.

And today I want to talk about several ways to enhance cellular communication on the phone with your own hands and how really they help. But before you perform any actions with your device, you need to make sure that it is working.

After all, poor reception may be due to a malfunction of the radio module, unreliable contact with the internal antenna, or firmware that has flown down.

Making sure that your smartphone is working is very simple. It is enough to compare its reception level with another, obviously working, not necessarily of the same model.

If it is very different, then most likely the mobile phone is faulty and it has a direct road to the repair shop. But there is no need to rush. I had a similar situation with Lenovo 316i, when the level bars on the display constantly disappeared, while other mobile phones worked fine. For some reason, I sinned on the buggy software.

And, of course, I tried to reflash it, but the result did not change. Having studied a considerable number of forums, I was inclined to the conclusion that the reason for the poor reception may be bad contact at the junction of the antenna and the motherboard.

This is a common disease of Chinese gadgets. The next step I decided to take was to disassemble it.

And in fact, having opened the case, I found that the middle spring tab on the board is slightly bent down and does not come into contact with the antenna, which is a flexible cable glued to the cover.

Armed with tweezers, I bent it up a little, screwed everything back on, replaced the SIM cards, the battery and pressed the power button. After the system booted, all four divisions appeared in the status bar and this time they did not disappear.

Thus, having skills and certain knowledge, I myself managed to repair my mobile. But now let's talk about the methods by which you can significantly improve the quality of communication.

Software way to amplify a cellular signal

This time we will not disassemble anything, but install it on Android special application MTK Engineering Mode, with which we will enter engineering menu and change some parameters there. It is free and you can download it from the Play Market. Please note that it is only suitable for devices based on MediaTek processor. You can find out which processor you have using the CPU-Z program, which you can download, again, from the Play Market. So, we click on the shortcut of the program and immediately get into such a menu.

Go to the MTK Settings tab

As a result, we will see such a window with settings on the display, where we remove all the checkmarks. We leave only

EGSM900;
DCS1800;
WCDMA-GSM-900.

Thus, we turn off unnecessary frequencies that are not used in our country.

We do the same operation with SIM2.

Then we go to the “Network Selection” where we select the GSM only item. This is a 2G communication standard, which originally appeared when building telecommunications networks.

It has wide coverage across the country and handles voice calls very well. Select this tab if you do not use 3G internet.

After these manipulations, your handset will work longer in time by disabling scanning unnecessary frequencies and keep the radio signal more stable, as it will not jump between WCDMA and GSM standards.

Connecting a homemade antenna

Previously, cell phones had an external radio antenna, or a plugged connector on the back of the case, into which any piece of wire could be plugged, which significantly increased reception.

Now everyone modern smartphones, to which, except for charging and headphones, you can no longer connect anything. But, if you disassemble it, then inside, on the board, you can see a small golden cylindrical connector with a hole in the middle.

It is intended for network diagnostics and is used only in service centers. But, if you insert a small piece (no more than 5 cm) of thin insulated wire, a noticeable increase in the signal level can be observed.

Only in this case it is necessary to comply with certain conditions. The wiring should not bend anywhere and touch the current-carrying parts. You can carefully lay it inside the case, between battery and cover.

Again, this method is not suitable for everyone, since most devices are non-separable or do not have such a connector.

Installing a repeater

This option is ideal for use in the country or in the countryside, where, as a rule, the quality of communication is not important due to the remoteness of the towers.

Its principle of operation is to capture electromagnetic waves, preamplify them and transfer them to the user's phone. The system consists of a block - a repeater, an external and internal antenna. The disadvantage of this equipment is the expensive price of the device, the complexity of installation, configuration and a small radius of action. But you can try to build homemade installation to amplify the signal.

To do this, we need a metal rod, about 50 cm long, a coaxial cable, a piece of foil about 100 by 40 mm in size, glued to plastic or plywood. It would be better if you have foil textolite.

So, we bend our rod in the shape of a rhombus and solder a cable to it, the other end of which is soldered to the foil.

An example of connecting a cable to a rod

We install our rhombus on the roof of the house or on a pole, preferably higher.

Now let's check the amplifier. To do this, we put the phone close to the plywood and notice how much the signal quality has improved.

sticker sticker

Often on sale you can find a universal compact antenna amplifier, which is a thin self-adhesive plate with a special geometric pattern of metal tracks, which, according to the manufacturer, reduce the amount of interference and can significantly enhance the signal where there is practically no cellular connection.

The sticker is glued to the inner surface of the phone, under the battery. But to buy it, in my opinion, there is no point. With the same success, you can put a piece of foil under the battery and the effect will be the same.

Here, with the help of such simple manipulations, you can, with the help of inexpensive materials, strengthen weak signal cellular connection on your phone.

P.S. I am attaching a screenshot of my earnings in affiliate programs. And I remind you that everyone can earn money in this way, even a beginner! The main thing is to do it correctly, which means to learn from those who are already earning money, that is, from Internet business professionals.

Modern mobile gadgets are necessary communication devices, without which it is already unthinkable to do, this technology has become so tightly integrated into our lives. However, even with full coverage, there are still areas where these devices may be in a "dead zone" or have a rather poor signal reception quality. As a rule, such places include not only the suburbs, but also megacities, the signal transmission in which is interrupted by many high-rise buildings. To solve this problem, the easiest way is to use special devices - cell signal amplifiers: external or internal. But how to make an antenna for a phone? This issue can be resolved by first understanding the features of their design.

An antenna for a mobile phone is necessary if the signal reception from the relay tower to the phone is of poor quality, which, as a rule, occurs due to the influence of a wide variety of factors. Before you start looking for a suitable additional antenna for your mobile phone, first of all, you should understand the principles of operation of the cellular communication itself.

A smartphone is a full-fledged miniature radio station that receives and transmits a signal in a certain frequency range (determined by the provider providing communication services).

The signal transmission parameters between the base station (repeater) and the mobile amplifier are commonly called “Down Link”, from a smartphone to an external antenna - “Up Link”. Note that, as a rule, providers almost always provide for some limitation when transmitting a signal from a base repeater (up to 35 km). This allows you to create a configuration that implies the implementation of 8 channels for the conversation of users. Such parameters are provided by the relevant communication standards. GSM operators provide fewer channels for conversation (no more than 3), however, in this case, the transmission duration increases and reaches 100 km. Often this cellular network configuration for an external antenna is used in the coastal part of the coverage area.

Features of choice

For phones with 3g technology support, not every connected mobile antenna is suitable. There are many factors that affect the quality of the signal received from the base station:

relief features;
geographical localization;
climatic conditions;
technical characteristics of both the antenna itself and the mobile device.

The most preferred place to place a 3g antenna for a signal amplifier is an elevation. This can be the roof of a building or a car, in the case of using external equipment for the vehicle.

In this case, it should be borne in mind that it is recommended to direct the amplifier for three or 4g towards the nearest repeater tower, which will help ensure better signal reception and transmission. Schematically, the placement of the antenna is shown in the figure.

Note! Installing an antenna for cell phone to enhance, you can improve the quality of communication not only on mobile phones, but also on other devices: laptop, tablet, PC and TV. Then general scheme will be more difficult. When improving the signal for all gadgets at home, the power of the antenna, modem and adapter used in the circuit is of great importance.

There is a remote model and equipment with a stationary device. There are options that connect to the phone and distribute a signal, like Wi-Fi. For amplification, you can use active repeaters and work with passive devices. The former additionally convert the signal, while the latter receive only due to their configuration.

In addition, there are several main types of devices:

wave receiver;
flat antenna;
parabolic antenna;
pin type antenna amplifier.

The design of the wave signal receiver includes the following elements: a traverse and reflectors perpendicular to it. This type of external amplifier does an excellent job of amplifying the signal, but requires fine tuning (pointing) of the device to the base station.

Flat outdoor antenna - this species remote devices has a fairly wide range of directivity. The device consists of an irradiator, which is built into the design of the reflector. An approximate direction to the repeater is selected for antenna tuning.

Parabolic external antenna - a device for outdoor placement, consisting of a feed and a reflector. The use of such an amplifier significantly enhances signal reception, but certain knowledge and skills are required to install an antenna for a telephone. With incorrect installation and configuration, the effectiveness of using this device will be minimal.

The rod-type antenna amplifier is a rod that simultaneously plays the role of a reflector and an irradiator. The design of this antenna implies a circular orientation. A prerequisite when using such an amplifier is the absence of screening devices that interfere with the reception of a signal transmission.

But how to connect the external and internal parts of the devices?

Connecting a mobile to an external antenna

To work in a smartphone, a cellular antenna requires a coaxial cable with a high-frequency connector. This is due to the fact that most mobile phones operate in the range of such frequencies. Note that the signal amplification efficiency directly depends on quality characteristics, both the connector itself and the cable products used.

If the design of the phone is not equipped with a socket to connect the antenna, you can use the device to solve the problem. speakerphone. In addition, you can use a method that is not comfortable for the user by wrapping the mobile with several turns of the antenna wire. Although in this case the use of the device is quite inconvenient, nevertheless, it allows you to achieve good signal reception in the phone.

Important! When using any kind of device, it is necessary that the antenna itself be positioned towards the repeater.

Diamond antenna, self-assembly

Often to buy antenna amplifier users do not have the means or opportunity to access a smartphone (place of residence in areas remote from large population centers). In this case, a person interested in improving the reception and transmission of the signal of his mobile phone can make a design for the phone with his own hands. In addition, even simple homemade products can connect well to the network and give the desired signal.

To create a device to improve the signal with your own hands, you will need a certain set of tools and materials:

pliers and a sharp knife designed to carefully remove insulation from cable products;
directly the cable itself (RG6) for connecting a mobile gadget to the antenna and a copper wire (2 mm cross section), its length must be at least 8 cm;
soldering tool with solder;
adapter for mobile device.

Antenna assembly procedure for mobile phone:

first of all, the insulation of cable products is stripped, while performing this work should be careful not to damage the inner core, which will subsequently be connected at one end to mobile device, and the other - to the antenna;
the copper wire is bent at the ends in such a way that a rhombus is obtained from both ends;
at the next stage, a copper wire is soldered to the cable core (strictly in the “up” position), the other part of the copper wire is soldered to the cable shielding braid (strictly in the “down” position);
then the copper wire is fastened to any surface of suitable size (a wide wooden plank is better), and one should not forget about the reliable insulation of all connections made during the assembly process;
the final design is placed on the roof of the building and securely fastened, the provided free end of the cable is lowered down and connected to the phone using a special adapter.

Important! It should be borne in mind that compliance with the placement of the copper wire will help to significantly improve the received-transmitted signal, even if it is almost completely absent.

A self-assembled design of a diamond-shaped cellular antenna is a very simple circuit to implement, which can be assembled by almost any user who does not have special knowledge and experience. The only condition for assembling a cellular connection with your own hands is the sequence of the above actions and the high-quality connection of all elements. The increase in signal is in direct proportion to the quality of performance.

Video

This post is about a very simple DIY. However, this is a necessary thing in extreme conditions. It has happened to everyone that in some particular place the phone does not catch the network well. It would be necessary to somehow increase the reception of the signal. But how? Can! We will make a universal antenna that will amplify the signal and quite well. What do you need to make at home.

Attention! To avoid damage, do not use expensive phones for the experiment! One of the comments under such recommendations: This thing where you stick a wire is called a network switch and it is really connected to the antenna, but sticking wires there or something else is a direct road to the repair shop, I will not convince anyone; yes, this method will amplify the signal, but with a probability of 50 to 50 you will wave the switch. And then your signal level will become much worse than it was before, the phone will work as if it had no antenna.

First, the phone. We open the case, inside a special socket for the antenna. A piece of copper wire. Can be isolated. Nail or other metal rod. From tools: soldering iron, solder.

It would be easier to twist all the connecting elements. But, it is better to do it thoroughly. It is necessary to solder and then isolate well. That's all! The antenna is ready. We put the battery, turn it on. Loading has occurred. We see only two sticks of the network indicator. We turn it off again. We insert the contact of the simplest antenna into the socket. We put the battery back. Turn on. Now the indicator shows as many as 6 divisions. Let's try to remove the antenna from the socket. Just one division. Now it remains to somehow aesthetically more or less arrange a homemade product. It turned out a phone with an antenna.

Another video about this method

I repeat once again, it is better to order a ready-made adapter, for the independent manufacture of an adapter, a special tool and special skills are required. A kit for self-wiring a pigtail ms-156, worth 80 rubles (long and short, I recommend a long one):

Contains pigtail, sleeve, heat shrink tube and cap. In addition, each RF connector is designed for a specific type of RF cable. Specifically, this pigtail is designed for the average:

Removing the outer cover:

We fluff the screen - the outer braid:

We clean the central vein:

Trying on the central vein:

We carefully solder the central core, it is important that the solder does not go beyond the groove. Do not forget to put on the sleeve and heat shrink so as not to solder. :)

Dressing the sleeve:

We press in. I overdid it and crumpled the central contact - you can’t do this, but it seems to work. The fact is that you need a special crimp in the form of a hexagon, but I crimped it with a regular crimp for contacts.

For dessert, put on heat shrink:

Testing and operating experience

For commissioning, I had to work with a soldering iron :). For a desktop antenna, I bought the cheapest adapter with ms-156 (I recommend a long one again !!!), the second connector was bitten off and the wire was soldered to the board. For the wave channel, the cheapest adapter with RP-SMA was bought (I first bought SMA, as I came I had to order the right one), the second connector was bitten off from it and the ms-156 pigtail was soldered. Speed measurement results: Built-in smartphone antenna:

Table Antenna:

wave channel

Table antenna switched to 2g.

Comments. In 2g mode, everything is slow and very sad, there is no sense from an external 3g antenna. An external antenna gives a tenfold increase in the outgoing speed of 3g traffic. The fact is that the Internet implies bidirectional data transfer. That is, a miniature two-centimeter built-in antenna needs not only to receive a signal from the OpSosa base station, but also to reach it in response. Now about the fact that with a wave channel, the speed is half that of a desktop one. In practice, the speed of 3g Internet is not constant, this will be written in the next section, with subsequent measurements, the speed with a desktop antenna was also low. However, from operating experience, I’ll say that sometimes it switches to 2g mode with a desktop modem, while the wave channel stably holds exactly 3g, the speed really floats, but it peaks up to 300-400 kilobytes / sec during the day. Thus - I recommend purchasing a 3g wave channel antenna with an rp-sma connector and an rp-sma adapter to ms-156. True, you will have to tinker with finding the base station, that is, the antenna will need to be directed exactly to the base station and fixed. A hole in the case of the modem / phone will have to be done in any case. The cost will be in the region of 1000-1500 rubles.

Recently, the coverage area of GSM 900 networks has significantly increased in Russia. Nevertheless, the situation is far from ideal. If in European countries the problem of uncertain reception is practically absent, then most domestic users often encounter it - in country houses, in summer cottages, etc. And how wonderful it would be to go fishing, hunting, to the village without losing touch with the outside world !

The key to solving this problem is external directional or non-directional antennas. True, buying an antenna is not enough - you need to install and configure it correctly. Readers familiar with radio electronics will be able to independently manufacture and configure an antenna operating in the GSM standard. Today we will talk about the types of antennas and how to install and configure them.

Reference
To put it quite simply, a mobile phone is a two-way radio that broadcasts on different frequencies. In total, there are 124 frequencies in the GSM 900 standard. The phone, like the base station, can operate on any frequency determined by the operator.

The base station (BS) transmits and the telephone (MS) receives on frequencies 935.2 - 959.8 MHz. The mobile phone transmits and the base station receives at frequencies of 890.2 - 914.8 MHz. The channel from BS to MS is called Down Link, from MS to BS - Up Link. Most operators use a limitation on the range of a mobile phone from a base station - 35 km, which is due to the peculiarities of the standard. Let us explain that in a standard configuration network, 8 time intervals (time slots) are formed in one frequency channel: one is service, and seven are conversational. It is in this case that the maximum communication range on each channel is 35 km. However, GSM also provides a non-standard cell configuration, in which the communication range is increased by 70 - 100 km (Extended Cell configuration). Unfortunately, with this configuration, the number of spoken channels is reduced to 2 - 3, which reduces the capacity of the network. Using this mode in the city and near the operator is not profitable. This mode is sometimes used on the coast to create coastal coverage.

Thus, if you have a GSM 900 phone, do not try to establish a connection more than 35 km away from the nearest base station. The maximum communication range achieved by me is 34 km.

Communication range
The following factors affect the radio range:

Location of BS and MS and terrain.

Power and sensitivity MS.

Power and sensitivity BS.

The will of the Lord God (experienced signalmen joke that this is the main thing).

Typically, base stations have a power of 20 - 30 watts. Antennas are either whip or directional. The sensitivity of base stations is -100 dB - 115 dB. Of course, the user cannot change or influence all these parameters. The output power of the phone is 0.3 - 2 W, the sensitivity is 90 - 105 dB. The sensitivity of a phone is mainly determined by the technologies used to create low-noise input devices. If in the areas of reliable reception the difference in sensitivity and power between the models is almost imperceptible, then in the area of uncertain reception it can become critical. Often, the handset shows a signal level from the base station of 1 - 2 cubes (on a scale), but cannot establish a connection: there is not enough power. And although the ETSI standardization regulates the standard output powers for each class of phones, the actual value may fluctuate slightly. SAGEM, Alcatel, Motorola tubes are distinguished by good sensitivity. And in terms of power, all old phones pass, especially Motorola. All phase 2 phones are about the same power.

As for the relief, waves spread better on flat terrain and along the river. The higher you are (within reason), the better the signal. The forest sometimes "extinguishes" the waves more than urban development.

Signal Search
So, you got out of the city and want to provide yourself with a connection. Climb to the roof, attic, or to the highest point near the house or the place you need. If the phone catches the network, but at the limit (or unstable), you have every chance to fix things using an external antenna. If the distance to the station is less than 30 km, and the network is not caught, also try using an antenna. In the latter case, try to negotiate with the sellers about the return of the antenna if the experiment fails.

If the signal, although very weak, was still caught, dial any city number - to check. If during a conversation the audibility is normal and the interlocutor does not complain about the loss of pieces of your speech, then the energy of both lines (UL and DL) is balanced and you can use a standard antenna tuned to the middle frequency between the receive and transmit frequencies. If the interlocutor disappears from time to time, it is necessary to "strengthen" the downward direction from the base station to your phone. It might be worth looking for a phone with better sensitivity. But if it's hard to hear you, you should amplify the direction from your phone to the base station. Already at this stage, it is clear that when choosing the type of antenna and its parameters, it is desirable to take into account the operator's data and reception conditions.

In areas of poor reception, interference (interference) is often observed between channels with the same and adjacent frequencies. Unfortunately, the frequency resource allocated to GSM 900 operators in Russia is limited, which is why frequencies from different base stations with the same or neighboring signal levels are often "visible" in the zone of uncertain reception. Such frequencies create mutual interference that interferes with communication, and at certain signal levels, communication becomes completely impossible. If a strong signal from the base station is fixed on the phone screen, and the connection cannot be established or it is possible, but the speech disappears all the time, then you are faced with "strangers". It is far from always possible to "force" the phone to select a different frequency, however, a special function Nokia phones- Netmonitor - allows you to do this.

I encountered a similar problem in a country house, which is separated from a large city by a rather open space. The phone received adjacent frequency channels with levels of 70 dB, 73 dB and 72 dB, but the call quality left much to be desired. The only thing that saved me was the forced selection of another frequency channel with a lower level - 80 dB. However, with a limited frequency resource, even frequency rescheduling of the network does not always help. However, if your phone does not have Netmonitor, you can use an external directional antenna with a good radiation pattern. It remains only to make the right choice.

Antenna selection
As already mentioned, it is external antennas that allow you to increase the range and quality of communication. For telephones, external whip and log-periodic antennas, as well as wave channel antennas, are mainly used. We repeat that in Western Europe there are no zones of uncertain reception. Therefore, directional antennas for GSM 900 terminals are practically not produced. If the manufacturer offers a directional proprietary GSM 900 antenna, it is usually designed to work with repeaters (repeaters) of operators.

In the CIS and Eastern Europe, directional antennas are made in a handicraft way. In addition, there are small factories in the Czech Republic, Poland and the Baltic States. A simple car magnetic antenna has a gain of 1 - 3 dB (1 - 2 cubes on the phone scale), a wave channel - 7 - 15 dB (depending on the number of elements, build quality and antenna settings), which is already 2 - 3 cubes on the scale , and log-periodic antenna - 7 - 12 dB. A car antenna is a vertical 3/4, 1/2, or 5/8 wavelength pole. Even a simple car antenna, raised higher, can correct the situation with an uncertain connection. The fact is that when talking on the phone, about 10 - 20% of the energy is absorbed by the user's body, therefore, raising whip antenna up, you reduce the influence of surrounding objects on it. I myself have observed how homemade, half-wave and vertical dipoles, raised 5 m, solved the problem of communication. Let us explain how such a dipole is made.

Rice. 1. Vertical dipole

We clean from one end the white television cable RG6U. We get the central conductor and the cable braid. We solder a copper wire of any thickness about 8.2 cm long (for the 900 MHz band) to the central conductor and fasten it vertically upwards. We solder a second piece of wire of the same length to the braid and fasten it vertically down (Fig. 1). We get something similar to the letter "T", laid on its side. (Television uses horizontal polarization, while GSM uses vertical polarization, so just such a dipole is required.) We connect the other end of the cable through an adapter to the phone. Be careful not to short the braided center wire, otherwise the phone may burn out. Well, in 5 minutes we built a primitive antenna, which is not inferior in parameters to Chinese automobile ones.

Let me give you a story from my life. Arriving last summer on vacation in the Crimea, I found that there is no reliable coverage on the basis of the promised operator. This meant that I would miss a very important call. A sure signal was found on the roof of the cottage, but the prospect of sitting there for two weeks did not inspire me. In 5 minutes I found a piece of the right wire (I used aluminum instead of copper). It took another 10 minutes to find a 5-meter piece from the neighbors television cable. The Nokia 7110 has a mechanical switch for the external antenna, so I just plugged the cable's center conductor directly into the phone jack and connected the cable sheath to the metal rim of the phone's external jack. He strengthened the antenna on the roof of the house and after 10 minutes, to the delight of the family and to the envy of the neighbors, he freely spoke on the phone.

As they say, back to our sheep. First, we will use a car whip antenna ($ 5 - 10).

The main thing here is not to run into too bad quality. With Netmonitor, checking the antenna is much easier. With a car antenna connected to the phone, the signal level should increase by 1 to 3 dB (for example, from -60 dB to -57 dB). As a last resort, the signal should remain the same. If, when connecting the antenna, the signal decreases by 5 dB or more, it is better to refuse to buy. I want to note that a good branded car antenna costs $40 and up. However, even among the Asian 10-dollar products, sometimes there are good little things.

Installed on the roof of your "house in the country", a car antenna can solve a communication problem. If the gain of the car antenna is not enough, you can turn to others - for example, to a common directional antenna - a wave channel. It looks like an ordinary television antenna installed on the roof of the house.

The wave channel allows you to get a real gain of up to 7 - 15 dB with an optimal directivity pattern. But it has a drawback - narrowband. The difference between the receive and transmit frequency in GSM 900 is 45 MHz, and the entire operating range is 890 - 960 MHz (70 MHz bandwidth). It is difficult to achieve a linear or close to linear response over such a wide range. Therefore, it is desirable to make the wave channel depending on the frequency of the operator and the specific location, and depending on the situation, shift the resonance to the frequency of the ascending or descending directions. For greater bandwidth, only a loop vibrator should be used, matching it with the cable - for example, with a balancing loop; you should also limit yourself to a small number of elements, say 3 - 12, since if there are more of them, it will be difficult to tune the antenna without equipment, in addition, the operating range of the antenna narrows.

I had to deal with a lot of handicraft wave channels. I state: in most antennas, the gain was less than 7 dB, some had a resonance at frequencies of 700 - 800 MHz instead of the GSM band and a standing wave ratio greater than 3 (during transmission, this can easily damage the phone's output stage). Professionally made and tuned homemade antennas were rare.

Now next in line are log-periodic antennas (they can also be found on the radio market). Compared to the wave channel, they have a wider operating range. Therefore, such antennas are less critical to the accuracy of manufacturing and tuning. The real gain here reaches 10 - 14 dB.

Theoretically, if necessary, you can connect 2 wave channels, one tuned to the receive frequency, the other to the transmit frequency, but this is already too complicated a system.

Cable and antenna adapters
In the 900 MHz band, the choice of cable becomes paramount. Domestic television coaxial cables can only be used to a limited extent (attenuation of more than 30 dB at 100 m is too high). Of the available imported samples, RG6 is a double-braided coaxial cable. You can find it in any store. Attenuation is 20 - 24 dB per 100 m (tested experimentally). Industrial whip antennas typically include RG59 cable with an attenuation of 28dB at 100m. A 12dB wave channel antenna and 10m of RG6U cable give a total gain of 9.6dB and at 20m 7dB.

Most phones have a connector for an external antenna. In addition, for each type of phone there is a so-called antenna adapter (about $ 5), it connects to the indicated connector and is a short piece of cable, on one side of which there is a specific high-frequency telephone connector, and on the other - a standard RF connector. Typically, the attenuation in the antenna adapter does not exceed 1 dB. When buying an antenna adapter, make sure it works. When the adapter is plugged into the phone, the antenna built into the phone is turned off and the output stage switches to the adapter. In other words, if you just connect the adapter to the phone, the signal on the phone scale should drop a little. Then you connect an external antenna to the adapter, and the signal increases. If everything goes that way, then the adapter is working.

Setting up the antenna on the ground
So, you bought an antenna and connected it to the cable and to the phone. We climbed to a high point and proceeded to tune the antenna. Position the phone so that the screen is visible. As already mentioned, when setting up the antenna with Nokia devices, it is best to use the Netmonitor function. On most other phones, you can enter special code and open the service menu, which allows you to see the reception level of 6 - 8 frequencies received by the phone in descending order, frequency numbers, distance to the base station, percentage of errors in the channel, etc. (Description of many service menus see: www.3ton.com/gsm.) If there is a Netmonitor, we will focus on the signal level in decibels (we remind you that the signal is stronger when the level value in decibels is lower). If it is absent, we will adjust according to the standard signal scale.

Since the base antennas GSM stations 900 are vertically polarized, the wave channel should be placed vertically. When aligning the antennas, please note that the receiving signal level displayed on the phone changes with a delay of up to several seconds, so the antenna should be rotated slowly and discretely. If you know the direction to the nearest city, start there. Slowly turn the antenna horizontally. If the signal is found, your task is to find the direction where the signal comes from with the maximum level. If there is no signal, slowly tilt the antenna horizontally until it appears. Remember that every meter of antenna installation height can be decisive. If no signal is found, try moving a few meters to the side and looking again. Maybe you'll get lucky.

It is undesirable to use a cable between the antenna and the phone with a length of more than 30 m: in this case, almost the entire signal is lost in the cable.

Finally, we give the dimensions of a self-made log-periodic antenna for the range of 850 - 950 MHz (Fig. 2). Dimensions taken from www.atnn.ru. The program for calculating the antenna-wave channel can again be found at: www.3ton.com/gsm.

This video tutorial shows you how to connect an external antenna to your smartphone. How to solder a connector for an external antenna to a mobile phone. A fly smartphone is used. The modem is already soldered. A 50 ohm low attenuation cable is used. It is inexpensive, available in any radio store. As a connector, a 75 ohm cable connection is used. Designed for a larger diameter, you have to put heat shrink at the end. Initially wanted to use other connectors. Made in the Soviet Union, very high quality, covered with technical silver. However, massive - it makes no sense to cling to gsm equipment.

It is unlikely that it will be possible to achieve a great effect in the field of strengthening communication. There are many articles on connecting an external antenna to a modem, but on the recommendation of the developer of gsm technology from 800 megahertz and above, it is advised to use only active antennas with a cable length of more than 10 cm. It is clear that if the plug is sealed, then there are already more than 10 centimeters. Active at home is difficult to make. Let's do the usual. But this is not the topic of the video lesson. Today we will just solder the connector, and we will perform the test in the wilderness, where there is practically no mobile communications.
Video of the channel "Automation, instrumentation, commissioning".

The GSM standard was invented by Europe in 1982, along with several related to communication via radiotelephones. The direction of the antennas was problematic, the transmitters were close to the person's head. The harm was noticed quickly, it is widely known: employees of enterprises involved in communications receive allowances wages. Without thinking twice, the standard committee introduced a new type of modulation that allows you to lower the power. Antennas were first made retractable, later they took the form of stumps protruding from the body of the apparatus. The filling rapidly decreased in size along with power supplies, the direction of small-sized antennas in the gigahertz range is relatively young. The first developments relate to the 50s of the last century. Do-it-yourself GSM antenna: how to make, where to install. Let's talk in more detail.

Development of the GSM standard, GSM antennas

Those who bother to look inside a mobile phone, another gadget, are powerless to see structures that resemble an antenna familiar to the eye. A well-thought-out manufacturer designs, more guided by experimental considerations, they are deprived of a harmonious theory. It makes no sense to think that the review will reveal the company's corporate secrets. Starting 3G, the standards are digital, there is a constant struggle to accommodate more information using fewer resources. They mentioned the harm, inside the cell phone the emitter is located in the area of the back wall, separated from the user by a ground screen. Microstrip technology has been known for a long time. The book of the 80s by Veselov describes the third part of the concept.

Cell phone GSM antenna efficiency is low, reaching 40%. Ordinary television sometimes go off scale for 90. However, people do not care, the harm to health is minimal. Each marsh sandpiper praises the cell phone, hears the interlocutor perfectly, when the connection is broken, the opponent’s sound disappears ... So, the cell phone is bad. The radiation pattern of the GSM antenna of a cell phone is one-sided - it does not shine in the direction of the speaker - it is strongly distorted. The user changes the alignment of forces with his hand, what to say about obstacles! Do-it-yourself GSM antenna is made to improve reception by stationary objects. Mobility is limited to the use of auto repair shops.

GSM antennas of transmitting stations are well equipped, they radiate perfectly. We hear the interlocutor (if he does not make sudden movements), the opponent will lose packets, while jogging, in transport. The phone takes on a fiver, it transmits much worse. Incoming packets with the opponent's voice arrive regularly, outgoing packets fail.

Now readers know: it is not possible to make a GSM antenna on microstrips at home. Eminent firms fight, solving a problem. It takes a minimum of time to assemble, design a functional, production is cheap. The layout of the insides (the antenna is not easy to fit in a modest space) is much more complicated.

On the territory of the Russian Federation, the following standards go:

GSM 900: transmit frequency 890 - 915 MHz, receive frequency 935 - 960 MHz.
GSM 1800: transmit frequency 1710 - 1785 MHz, receive frequency 1805 - 1880 MHz.

A microstrip antenna consists of a radiator, a dielectric substrate, and a conductive screen. With an increase in the thickness of the emitter, the operating range increases, a tenth of the wavelength. The thickness of the dielectric is less than the specified value. Let's talk casually. AT Wi-Fi range microstrips are combined with gratings, sealed with a plastic case, equipped with a single screen, act as a single team, allowing you to get good gain, therefore, to catch a more distant signal. The towers are fixed and in direct line of sight. If it is true what is said in a particular situation, the solution is suitable.

Here is a picture (website http://www.carookee.net/) of a 2.4 GHz antenna. To start working at a frequency of 1800 MHz, it is necessary to increase the dimensions proportionally in a ratio of 4 to 3. Please note that this applies to all lines, including connecting ones. At first, try the functioning of one square until the getinax fee is reduced to the sacrifice of the needs of mobile communications. The scale of the portal is wrong - see the drawing provided with dimensions, the arrows are shown. Image taken from http://www.zero13wireless.net/. The numbers are in millimeters. Proportionately remove drawing number one, determine the dimensions. The pads are square, if distorted, correct with a graphical editor, even Paint, which is included by default with Windows, will do.

For other frequencies, feel free to extrapolate the drawing to all occasions in proportion to the ratio of wavelengths. Divide 2400 MHz by the standard GSM band. Above we took the ratio 2400/1800. By doing so, readers will choose desired device GSM antennas. Containing 4x4 squares gives less gain (amplification of the GSM antenna signal), it is easier to aim. The reception is blurry, it is not clear where the signal comes from, the design is in place. In the case of a distant tower, clearly visible on the horizon, 9 squares will be appropriate. Please note that the feeder to the phone (other receiving device) should not be long, the signal will attenuate on the way here, in the cable. I want to put the device on the roof ... assemble a microstrip amplifier, buy ready-made in the store for the desired frequency. Ask for the number you need mobile operator. A public frequency service has been created, ask officials to talk to private traders.

GSM antenna manufacturing

Most readers have grasped how a homemade GSM antenna can be made. The craft will require a getinax board of a suitable size for double-sided foiling. Copper is applied from one side - it will be necessary to add a reflector structure from a sheet of steel, another metal, with an area exceeding the emitter. Then copper is drawn by the future contour of the antenna. Do it more carefully using a ruler and a corner. Then:

The area under the antenna is varnished, suitable for women's nails. The composition should not get on the surface in other places, at the joints, you can paint over large islands, then peel off with a knife (to increase processing speed).
The boards are etched with copper sulphate. Foiling is double-sided - the rear is completely painted over with varnish. Otherwise, the screen will not dissolve! Just etching will not end in a conceivable period. Copper sulfate is not enough. The second side is not needed - they tear it off with a knife. To save the screen you need to paint with varnish.
Etching is carried out until unnecessary areas of copper are washed off, the finished GSM antenna is washed with water, dried, problem areas are cleaned with a knife.
The product is placed inside a sealed plastic case, suitable for the dimensions on the racks, not affecting the metal part. The screen must be grounded. Try to put on the braid of a coaxial cable. Reminder: WiFi uses 50 ohm impedance wire. How much to take for cellular communications: 50 looks appropriate because 900 MHz television is ending.

Varieties of GSM antennas

Much has been written about antennas for WiFi, readers guessed: the ranges are very similar ... just take the drawings, transfer them to other frequencies, sizes are indicated everywhere in relation to the wavelength. Transpose the thumbnails proportionally. The procedure is listed above. It is easy to find the so-called Kharchenko antenna (bi-square) on the network, which is a pair of frames with one common point. More advanced solutions were cited, characterized by greater gain.

Readers will have a choice of which remote GSM antenna will be manufactured. Kharchenko's bi-square design is performed by radio amateurs from strips 10 mm wide, with a square side in the center of 80 mm. The dimensions were not checked, the dimensions are determined by the wavelength used by the GSM standard. For 900, 1800 MHz, the difference will be two times. Carefully check the dimensions of the drawings. The frame should be proportional to a quarter of the wavelength. The formula is known from the course of physics, it makes no sense to give four drawings that differ in small details. You need to understand: an external GSM antenna is similar in structure to WiFi, we believe that any of the sections can be moved here. The difference is limited by frequency, modulation. The first does not affect reception, the second determines the dimensions of the GSM antenna.

When using an extension cord, try to place the amplifier close to the mounting point. Wire noise greatly reduces the sensitivity of the device.

Reference

To put it quite simply, a mobile phone is a two-way radio that broadcasts on different frequencies. In total, there are 124 frequencies in the GSM 900 standard. The phone, like the base station, can operate on any frequency determined by the operator.

Thus, if you have a GSM 900 phone, do not try to establish a connection more than 35 km away from the nearest base station. The maximum communication range achieved by me is 34 km.

Communication range

The following factors affect the radio range:

Location of BS and MS and terrain.

Power and sensitivity MS.

Power and sensitivity BS.

Used on MS and BS antennas.

The will of the Lord God (experienced signalmen joke that this is the main thing).

Signal Search

So, you got out of the city and want to provide yourself with a connection. Climb to the roof, attic, or to the highest point near the house or the place you need. If the phone catches the network, but at the limit (or unstable), you have every chance to fix things by using an external antenna. If the distance to the station is less than 30 km, and the network is not caught, also try using an antenna. In the latter case, try to negotiate with the sellers about the return of the antenna if the experiment fails.

In areas of poor reception, interference (interference) is often observed between channels with the same and adjacent frequencies. Unfortunately, the frequency resource allocated to GSM 900 operators in Russia is limited, which is why frequencies from different base stations with the same or neighboring signal levels are often "visible" in the zone of uncertain reception. Such frequencies create mutual interference that interferes with communication, and at certain signal levels, communication becomes completely impossible. If a strong signal from the base station is fixed on the phone screen, and the connection cannot be established or it is possible, but the speech disappears all the time, then you are faced with "strangers". It is far from always possible to "force" the phone to select a different frequency, but a special function of Nokia phones - Netmonitor - allows you to do this.

I encountered a similar problem in a dacha, which is separated from a large city by a rather open space. The phone received adjacent frequency channels with levels of 70 dB, 73 dB and 72 dB, but the call quality left much to be desired. The only thing that saved me was the forced selection of another frequency channel with a lower level - 80 dB. However, with a limited frequency resource, even frequency rescheduling of the network does not always help. However, if your phone does not have Netmonitor, you can use an external directional antenna with a good radiation pattern. It remains only to make the right choice.

Antenna selection

As already mentioned, it is external antennas that allow you to increase the range and quality of communication. For telephones, external whip and log-periodic antennas, as well as wave channel antennas, are mainly used. We repeat that in Western Europe there are no zones of uncertain reception. Therefore, directional antennas for GSM 900 terminals are practically not produced. If the manufacturer offers a directional proprietary GSM 900 antenna, it is usually designed to work with repeaters (repeaters) of operators.

In the CIS and Eastern Europe, directional antennas are made in a handicraft way. In addition, there are small factories in the Czech Republic, Poland and the Baltic States. A simple car magnetic antenna has a gain of 1 - 3 dB (1 - 2 cubes on the phone scale), a wave channel - 7 - 15 dB (depending on the number of elements, build quality and antenna settings), which is already 2 - 3 cubes on the scale , and log-periodic antenna - 7 - 12 dB. A car antenna is a vertical 3/4, 1/2, or 5/8 wavelength pole. Even a simple car antenna, raised higher, can correct the situation with an uncertain connection. The fact is that when talking on the phone, about 10 - 20% of the energy is absorbed by the user's body, therefore, by raising the whip antenna up, you reduce the influence of surrounding objects on it. I myself have observed how homemade, half-wave and vertical dipoles, raised 5 m, solved the problem of communication. Let us explain how such a dipole is made.

Rice. 1. Vertical dipole

Let me give you a story from my life. Arriving last summer on vacation in the Crimea, I found that there is no reliable coverage on the basis of the promised operator. This meant that I would miss a very important call. A sure signal was found on the roof of the cottage, but the prospect of sitting there for two weeks did not inspire me. In 5 minutes I found a piece of the right wire (I used aluminum instead of copper). It took another 10 minutes to find a 5-meter piece of television cable from the neighbors. The Nokia 7110 has a mechanical switch for the external antenna, so I just plugged the cable's center conductor directly into the phone jack and connected the cable sheath to the metal rim of the phone's external jack. He strengthened the antenna on the roof of the house and after 10 minutes, to the delight of the family and to the envy of the neighbors, he freely spoke on the phone.

As they say, back to our sheep. First, we will use a car whip antenna ($ 5 - 10).

Installed on the roof of your "house in the country", a car antenna can solve a communication problem. If the gain of the car antenna is not enough, you can turn to others - for example, to a common directional antenna - a wave channel. He looks like a normal TV antenna installed on the roof of the house.

Theoretically, if necessary, you can connect 2 wave channels, one tuned to the receive frequency, the other to the transmit frequency, but this is already too complicated a system.

Cable and antenna adapters

In the 900 MHz band, the choice of cable becomes paramount. Domestic television coaxial cables can only be used to a limited extent (attenuation of more than 30 dB at 100 m is too high). Of the available imported samples, RG6 is a double-braided coaxial cable. You can find it in any store. Attenuation is 20 - 24 dB per 100 m (tested experimentally). Industrial whip antennas typically include RG59 cable with an attenuation of 28dB at 100m. A 12dB wave channel antenna and 10m of RG6U cable give a total gain of 9.6dB and at 20m 7dB.

Setting up the antenna on the ground

So, you bought an antenna and connected it to the cable and to the phone. We climbed to a high point and proceeded to tune the antenna. Position the phone so that the screen is visible. As already mentioned, when setting up the antenna with Nokia devices, it is best to use the Netmonitor function. In most other phones, you can enter a special code and open a service menu that allows you to see the reception level of 6 - 8 frequencies received by the phone in descending order, frequency numbers, distance to the base station, percentage of errors in the channel, etc. (For a description of many service menus, see . at: www.3ton.com/gsm.) If there is a Netmonitor, we will focus on the signal level in decibels (recall that the signal is stronger when the level value in decibels is lower). If it is absent, we will adjust according to the standard signal scale.

Since the GSM 900 base station antennas are vertically polarized, the wave channel should be placed vertically. When aligning the antennas, please note that the receiving signal level displayed on the phone changes with a delay of up to several seconds, so the antenna should be rotated slowly and discretely. If you know the direction to the nearest city, start there. Slowly turn the antenna horizontally. If the signal is found, your task is to find the direction where the signal comes from with the maximum level. If there is no signal, slowly tilt the antenna horizontally until it appears. Remember that every meter of antenna installation height can be decisive. If no signal is found, try moving a few meters to the side and looking again. Maybe you'll get lucky.

It is undesirable to use a cable between the antenna and the phone with a length of more than 30 m: in this case, almost the entire signal is lost in the cable.

Parameters: gain - 8.3 dB, impedance - 60 ohms.

Diagnosing and troubleshooting a GSM module is one of the most difficult and time-consuming. For diagnostics, it is recommended to use a GSM tester. For example, like this:

Will "tek GSM tester

However, it is very expensive and a novice master cannot afford to buy it. In the future, this device should be purchased.

It is necessary to clearly distinguish between malfunctions of the receiving and transmitting paths, and also take into account what they have in common. antenna switch, which is made on a fragile ceramic substrate and often cracks when dropped and bumped.

As a result, the phone does not see the network, or it sees it, but cannot register. In many phones, the antenna switch and power amplifier (and sometimes the transceiver too) are combined into one chip.

Typical malfunctions of the GSM module:

1. The phone "does not see" the network- a permanent message on the display of the phone such as: "no network" or the like and, accordingly, the absence of strips (marks) of the indicator of the intensity of the electromagnetic field of the GSM network. First you need to check if the phone finds the network in manual search mode. If the networks are found, it can be assumed that the receiving path of the GSM module is in order and the phone cannot register in the network, since it is not possible to send a registration request. The fault should be sought in the transmitter, power amplifier (Power Amplifier), as well as in the antenna switch.

If the phone does not find any network, the check should be started sequentially as the signal passes, that is, from the antenna to the transceiver.

An external inspection of the antenna and the contact leads of the antenna circuits of the telephone board is carried out for the absence of oxides, deformation or absence of spring contacts for connecting the antenna, as well as antenna breaks, made in the form of a thin loop glued to one or another body part of the phone.

Almost every phone is equipped with a diagnostic connector, which is designed to connect a GSM tester or an external GSM antenna (for areas of poor signal reception).

Since this connector is in series between the antenna and the input circuits (switch, and so on), if the contact of the internal contact group of the connector is broken as a result of exposure to moisture, oxides, fur. influences, the antenna is disconnected from the phone. It is checked by a dial-up tester and, if necessary, replaced with a known-good one. It is also possible to replace the connector with a jumper. In this case, the function of connecting a GSM tester or an external antenna will not be available. It should be noted that the connector contact may not be completely absent, but may have a resistance from hundreds of milliohms to several ohms. However, for such ultra-high frequencies of the GSM range, there will be huge signal losses (attenuation) at such resistance and, accordingly, the phone will not see the network, or the level will be very low and constantly "float".

The next element that fails as a result of drops and shocks is the 850/900MHz and 1800/1900MHz filter - each for its own frequency range.

Without a GSM tester and / or an oscilloscope, a faulty one can only be identified by replacing it with a known good one.

When falling and hitting, the soldering of the GSM module chips is often disrupted, and in some cases the Power Amplifier fails and gives a short circuit in the power supply. Soldering or replacement of the corresponding microcircuits is performed.

2. The phone registers on the network, but the call cannot be made. This defect can occur for several reasons:

Incorrect software setting ( software) phone - the "Hide number" option is selected if the operator does not support this feature by default. Dialing stops almost immediately after pressing the "Call" button. You must select the option "Set by network", "Show number" or others, according to the menu items of a particular phone.

Poor shielding of the GSM module. Applies to phones whose shielding is made in the form of a metallized coating back cover corps. Over time, the transition contacts (to connect the shielding to the common wire of the board) oxidize, the coating falls off, and when you call, part of the power emitted by the power amplifier and antenna is induced on the elements and circuits of the telephone board. Characteristic for Samsung phones X100, X480 and the like.

Phone software failure. Violation of the settings of a special memory area containing all kinds of calibrations, security data, etc. Each phone has its own name. For example, for NOKIA - PM (Permanent Memory), for Sony Ericsson- GDFS (Global Data File System), for Samsung - EEPROM (Electrically Erasable Programmable Read-Only Memory), etc. Sometimes you can restore performance full reset settings to factory defaults through the appropriate menu item, usually called "Reset settings" or "Restore factory settings" or do it using a special service code (not supported by all phones). The most effective way is to restore the software using the appropriate programmer.