I decided to acquire mobile phone to communicate with suburban a plot. It turned out that the network is unstable, was observed connection breaks, loss of words. The probable cause of this phenomenon is the large distance to the base station. Indeed, if you climb the tree quality is good, and the house - not very.
The solution to this situation is to install an external antenna. Of course, such antenna sold in firms specializing in accessories for mobile communications, but the price these antennas is usually high. The idea to make a simple antenna independently. Decided to start to try what I've tried to receive television in the UHF range - double triangular antenna. It is quite detailed described in the article In Mikhailov's "Antenna UHF for an hour of work" (see "Radio" No. 6 for 1998).
The drawing of an antenna designed for the 900 MHz range, shown in the figure.
Material - coated fibreglass or plated hardened paper (the latter is better - foil easier torn off). Mark the sheet, cut the foil with a knife or a cutter, then remove unnecessary portions. Cable - 75 Ohm, solder braid to the bottom half of the antenna, and the center conductor to the top. Then run the cable as shown in the figure. A and B - the point of zero potential, attach it to the mast, which may be metal. Since the polarization of the electromagnetic waves in cellular vertical, the antenna is set so that the point a was at the top and B for bottom.
You can even add a reflector, but not necessarily. The dimensions of the reflector 170x150 mm., It is attached at a distance of 65 mm from the leaf antenna. Can use metal fasteners, if screwing it in zero points of potential.
The leaf antenna (or rather, foil) must be covered by any varnish or glue for corrosion protection. Cable length should be limited to such frequencies, it has an attenuation of about 1 dB/m, and the gain of the antenna 5...6 dB.
The best way to connect the antenna to the phone through a special cord (antenna the adapter). If the cord is not present, and the phone is supplied with whip antenna, to make the coil and connect the external antenna through it. The end of the cable clear of exterior insulation and braid length 25...30 cm center conductor in isolation is wound on a metal rod (such as a drill) diameter which corresponds to whip the phone's antenna, fixed thread and slightly heated (for example, attaching a rod to a hot soldering iron). After cooling get a decent spring, which put on regular antenna of the phone. The number turns - 5-7. The coil leads are soldered to the connection cable. The results of the application the antenna has surpassed all expectations.
Author: M. Nicoletto, Moscow