On quality and type of the radio antenna, correctness of its mounting depends, how surely the TV will accept TV signal. Therefore when choosing the antenna it should be taken into account that there are several types of this device.
In spite of the fact that the number of the channels accepted by radio antennas is limited, the popularity of these designs is at the high level. It is connected with the fact that devices combine such attractive qualities as low cost, lack of monthly fee for use, simplicity of mounting.
Design, operation principle of the radio antenna
For normal reception of TV channels on antenna entrance of the TV there has to be tension within 320-500 mkv. That to reach it, the antenna has to have certain design. The main element – the poluvolnovy vibrator which can be loopback, linear cutting and linear continuous-solid is the cornerstone of each radio antenna. Regardless of design the vibrator has the directional pattern in the form of the eight located in the antenna plane therefore the highest level of signal is towards the main lobe of the radio antenna. One more element of the antenna – most often is the rod located in front of the half-wave vibrator. Behind it the reflector is located, - most often too rod, but the big sizes. Also on the general bar several passive vibrators are fixed. As material of production of the antenna usually serves aluminum or anticorrosive alloys.
Types of antennas
The simplest option – frame antennas. It the devices which are not demanding any settings. Sometimes, for increase in coefficient of strengthening the antenna is done in the form of several frames connected among themselves. The design like "dipole" which can be wave, half-wave or quarter wave is not less widespread. Here length of vibrators corresponds to wavelength or is from it ½, ¼. Devices which are the system consisting of several small antennas are more difficult on the device lattice (or cophased). The design represents several grids located on one rod. The "Polish" antennas which popularity is caused by opportunity to accept the weakest signals thanks to availability of the built-in amplifier also belong to such devices. The log-periodic antennas belonging to the category of broadband satellite devices stand a little "alone". These devices are capable to accept signals on several channels in wide frequency range at once: the greatest vibrator, for high – the smallest "is responsible" for low frequencies. One more type of the antenna, type "the running wave", differs in the high level of orientation since the wave of the entering signal passes along geometrical axis. This device is considered ideal for acceptance of the satellite Internet.