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In the CIS and Eastern Europe, directional antennas are made artisan. In addition, there is no large-factory in the Czech Republic, Poland and the Baltics. A simple magnetic car antenna has a gain 1 - 3 dB (1 - 2 dice on a scale of the phone), Yagi - 7 - 15 dB (depending on the number of elements, build quality and adjust the antenna), which is already 2 - 3 dice on a scale and log-periodic antenna - 7 - 12 dB. Car antenna is a vertical pin in 3 / 4, 1 / 2 or 5 / 8 wavelength. Even a car antenna, raised higher, could improve the situation with an uncertain relationship. The fact is that when talking on the phone for about 10 - 20% of the energy absorbed by the body user, therefore, raising the whip antenna up, you reduce the impact on its surroundings Google. I watched as improvised, half-wave dipole and the vertical raised to 5 m, solve the problem of communication. We explain how such a dipole is made. In Fig. 1. Vertical dipole In Fig. 1. Vertical dipole We clean c one end of the cable television white RG6U. Obtain the center conductor and braided cable. By the center conductor solder the copper wire of any thickness about 8.2 cm in length (for a range of 900 MHz) and fasten it vertically. By the second braided solder a piece of wire the same length and fasten it vertically downwards (Fig. 1). We get something like the letter "T", the provisions on its side. (The TV uses horizontal polarization, and GSM - vertical, so you need just such a dipole.) Other end to connect through the adapter to the phone. Be careful not to short-circuit the central core with braided, otherwise the phone may be burned. Well, for 5 minutes, we built a rudimentary antenna can compete in China's auto settings. Here is the story of life. Arriving last summer on vacation in the Crimea, I found that on the basis of the promise by the operator confident there is no coverage. This meant that I missed a very important call. Sure the signal showed up on the roof of the cottage, but the prospect to sit there for two weeks I was not inspired. Within 5 minutes I found the right piece of wire (copper instead of aluminum used). Another 10 minutes went out to find the neighbors of 5-meter long piece of cable television. Nokia 7110 has a mechanical switch for an external antenna, so I just stuck the center conductor cable directly into the phone jack and cable shield connected to the metal rim of the external terminal device. Strengthened the antenna on the roof of the house and within 10 minutes to the delight of the family and the envy of the neighbors to communicate by telephone. As they say, will return to our sheep. First, we use the car whip antenna ($ 5 - 10). Here the main thing - do not run into too bad quality. With Netmonitor, check the antenna much easier. When connected to a phone car antenna the signal strength should increase by 1 - 3 dB (for example, -60 dB to -57 dB). In an extreme case, the signal must remain unchanged. If you connect the antenna signal is reduced by 5 dB or more, it is better not to buy. Please note that a good branded car antenna costs $ 40 and above. However, among Asian and 10-dollar items are sometimes found good pieces. Installed on the roof of your "house in the village", a car antenna is able to solve the problem with communication. If the antenna gain is not enough car, you can refer to another - for example, a common directional antenna - the wave channel. It looks like a regular TV antenna, installed on the roof. Yagi provides a real gain of up to 7 - 15 dB with an optimal radiation pattern. But it has a drawback - a narrow band. The difference between the frequency reception and transmission frequency in the GSM 900 MHz is 45, and the entire working range - 890 - 960 MHz (bandwidth of 70 MHz). Achieve a linear or nearly linear characteristics in a wide range of difficult. It is therefore desirable to produce a wave channel, depending on the frequency of the operator and the specific location and depending on the situation, move the resonance frequency for ascending or descending direction. For most broadband should only be used folded dipole, coordinating it with a cable - for example, balancing a loop; also should be limited to a small number of elements, say, 3 - 12, as if there will be more, adjust the antenna without the equipment will be difficult, moreover, operating range of the antenna is shrinking. I had to deal with multiple wavelengths, home-made. Stating: Most antenna gain of less than 7 dB, some had a resonance at 700 - 800 MHz instead of the GSM-band and standing-wave ratio greater than 3 (when transmitting it can easily disable the output stage of the phone). Professionally made and customized homemade antennas were rare. Now on stage - log-periodic antenna (which also can be found in the radio market). In comparison with the wave channel they have a wider operating range. Therefore, such antennas are less critical to the accuracy of fabrication and tuning. The real gain here is 10 - 14 dB. Theoretically, if necessary, you can connect two of the wave channel, one - tuned to the frequency of administration, the other - on the frequency of transmission, but it is already too complex system. Cable and Antenna Adapters In the 900 MHz band cable takes a matter of choice of primary importance. Domestic television coaxial cables can be used only partially (attenuation 30 dB at 100 m is too large). Of the available import samples suitable RG6 - Coaxial cable with double braid. You will find him in any store. Attenuation of 20 - 24 dB at 100 meters (tested experimentally). Industrial whip car antennas typically include cable RG59 with attenuation of 28 dB at 100 m. The antenna type wave channel with a gain of 12 dB and 10 m cable RG6U provide an overall gain 9.6 dB, and at 20 m - 7 dB. On most phones have a jack for an external antenna. In addition, for each type of phone there is a so-called antenna adapter (about $ 5), it connects to the specified port and a short piece of cable from one side of which is a particular phone jack high, but on the other - a standard RF connector. Typically, the attenuation in the antenna adapter does not exceed 1 dB. Buying an antenna coupler, make sure it is capacity. When you turn the phone adapter built into the phone antenna is turned off and the output stage switches on the adapter. In other words, if you simply plug the adapter to the phone, the signal at the scale of the phone has a little fall. Then you connect an external antenna to the adapter and the signal increases. If all goes that way, then the adapter is working Mobile phone spy. Setting up the antenna on the ground So, you bought an antenna and connected it to the cable and the phone. Climbed to the highest point and began setting up the antenna. Place the phone so that the screen was visible. As mentioned earlier, when configuring the antenna devices Nokia is best to use the function Netmonitor. In most other phones, you can enter a special code and open the service menu that allows you to see the reception level of 6 - 8 frequencies, taken in descending order of phone numbers of frequencies, the distance to the base station, the percentage of errors in the channel, etc. (For a description of many service menu cm . at: www.3ton.com/gsm.) Netmonitor If there is, we shall be guided by the signal level in dB (note that the signal is stronger when the level value in dB less). If it is not, we will be configured on a standard scale signal. Since the antenna GSM base stations 900 have a vertical polarization wave channel should be placed vertically. The alignment of antennas note that the receiving signal strength displayed on your phone, change a delay of several seconds, so the antenna should be rotated slowly and discreetly. If you know the direction to the nearest town, start with him. Slowly turn the antenna on the horizon. If a signal is found, your task is to find the direction from which the signal comes from the maximum level. If there is no signal, slowly turn the antenna on the horizon, until it appears. Remember that every meter height of the antenna can be decisive. If the signal is not found, try to move a few feet away and look again. Maybe you're lucky. It is undesirable to use a cable between the antenna and the phone longer than 30 m in this case, almost all the signal is lost in the cable.
