As is known, to the territories covered with reliable cellular communication, abut areas where communication is not guaranteed. Usually this is because because of the terrain straight wave is very weak and the electromagnetic field is formed in the radio shadow is formed by the reflected rays. Passing different ways and phase shifting, they create in this space very complex interference pattern. The field strength in the radio shadow changes very sharply, and local maxima can reach a level at which the connection is quite possible.
In real conditions it is impossible to predict neither the location of the local highs nor the field strength in them. However, they can be detected experimentally: it is at these points on the scoreboard cell phone occurs the greatest number of "blocks". Such maximum can be detected and inside the building, but he will most likely be small. Sufficient to regard the peak field strength better to look outside, wall facing the nearest base station. Experience shows that this peak is often located very close to the wall, any 10...20 cm.
By placing the mobile device in the maximum point, you can establish a connection. But take call the reporter, the time of occurrence of which is not known, will not succeed. If, of course, not to hold the phone at this point constantly. Essentially, communication becomes one-sided.
If found in the point to place the antenna with gain, ie directional antenna, and associate it with a mobile camera coaxial cable, the loss will be less antenna gain, then the connection will be more stable and it will be possible not only to make outgoing calls but can receive calls. Thus will have to put up with the inconvenience, as the device will be linked by cable to the antenna.
Estimate the required antenna gain, working in conjunction with thin coaxial cable RK-50-3-13, length 3 m. This cable has an attenuation at a frequency of 1000 MHz of 0.65 dB/m at 1800 MHz frequency - of 0.87 dB/m. Obviously, would have sufficed 3-0,87 - 2,6 dB. In other words, to compensate for losses in the cable there is no need to acquire expensive antenna having a gain of 15 dB 10... (a significant portion of these decibels "used up" in her 10-meter cable).
A suitable antenna for these purposes can serve as a well-known table television automatic process antenna UHF, if all its elements to shorten twice (inter-element distances remain former). If you have a choice, we should choose the antenna former design - with one-piece dipole paintings.
The antenna is installed in the orientation for vertically polarized signal (in the vertical plane) at the point found by the phone, but the final the position needs to be clarified. In the antenna socket adapter include (adaptor), which, in turn, connect the antenna cable through the necessary high-frequency connectors. Slowly moving the antenna to find such her position, which corresponds to the maximum number of "blocks" on the indicator the received signal of the phone. This should be done slowly, because the update information on the indicator occurs with some delay.
When you install the antenna outdoors, it can be placed in plastic bag to protect from moisture. The small size of the antenna allows it to do.
Author: Y. Vinogradov, Moscow