Fixed antenna-feeder devices

On the stationary transmitting radio centers to ensure close communications (1,000 km) non-directional and omnidirectional used the range dipole antenna type UGD (angled horizontal range), IOP, VGDSH, VGDSHP and VGPSH (planar). For the organization of long-distance communications are used directional antenna radiation — rhombic (WG), double rhombic (RGD), horizontal in-phase (SGDRA) and the log-periodic (LPA).

When working at a distance of 1,000 km using 3-4 UGD antenna size and antenna size 2-3 IOP VGDSHP and VGPSH. The average values ​​of gain (CG) and directional (CPV) antenna near-field communication, taking into account the real parameters of the land are in the range of 1.5-2.5 and 3-5 (for the non-directional) to 3-7 and 6-12 (for omnidirectional). The same antenna, providing maximum radiation angle in the vertical plane of 20 to 90 deg., Have a beamwidth (NAM) in the horizontal plane from 40-110 ° (omnidirectional) to 360 degrees (non-directional).

It should be emphasized that the magnitude of the CPV and KU correspond to the directions of maximum radiation (up to DN). When working outside the permissible azimuth and elevation sectors of the direction of emission (reception) do not coincide with peaks and will be located on the slopes of the radiation pattern. In these cases, the CPV and KU decreases with the square of the field level. For example, if the level of the normalized NAM selected direction is 0.5, the CPV (CS) compared with the direction of maximum Nam drops 4 times (6 dB).

It is also necessary to pay attention to the fact that the admissible expansion of the working range of the antenna VGDSH towards lower frequencies is limited and does not exceed 4%, whereas for antennas IOP it reaches 25%.

In order to communicate over long distances using multiple sizes of antennas. Most often used on each track are two rhombic antennas to work in the daytime and at night. In order to reduce the number of antennas and increasing the rate of their use rhombic antenna equipped with technical devices, providing rezers (switching the direction of radiation).

Power transmission antennas near and distant relations by means of four-crossed overhead feeders to the characteristic impedance of 300 ohms. The coefficient of the traveling wave in the short-range antenna feeder should not be less than 0.25, and feeders and rhombic period antennas 0.5-0.6 above. The coefficient of amplitude asymmetry in the main working range shall not exceed 5%.

It should be noted that in the absence of directional radiation antennas (reception) in a predetermined direction by the stationary radio centers possible to use omnidirectional antennas for very long routes (2,000 km). In this case, the necessary conditions for their use are as follows: fabric dipole antennas perpendicular to deploy a given direction, the height of his suspension should be more than half, and the length of the arm of the vibrator should not exceed 0.7 times the length of the working wavelength.

On receiving steady radio centers for short-range communication using the antenna type UGD, IOP, and for long-distance connections — rhombic antennas and multiple transducer arrays of antennas traveling wave — BS-2, 2-2BS, BSL-2. Receiving antennas transmit different from what they are designed for low power signals. Antenna type BS in most cases have the opportunity to reverse the direction of reception.

To provide polarization diversity reception at radio centers used BS antenna with horizontal blades and unbalanced antenna BSVN2, 2BSVN2 and ZBSVN2 (receiving vertically polarized field), whose paintings are hung on poles antennas respectively BS2, and 2BS2 ZBS2. The coefficient of a traveling wave in the antenna feeder type aerial BS should not be lower than 0.6 and the ratio of the amplitude of asymmetry does not exceed 5%.

Power receiving antennas for the near and distant relations is carried out either by a four-aircraft crossed the feeder or feeder cable with characteristic impedance of 200 ohms and 75 respectively. In the latter case, a broadband amplifier mounted antennas.

A characteristic feature of receiving and transmitting radio stationary centers is the presence of a large number of these different types of antennas, some of which are located at a significant distance (1 km) from the maintenance of the building. Therefore, during the operation of the antenna fields is necessary to consider the possible deterioration of the air feeder lines due to the weather. Thus, when frost settling on the feeder lines in the attenuation of them may increase by tens and hundreds of times (up to 10-20 dB and more).

To improve the reliability and quality using a shortwave radio antenna-feeder devices (AFD) must comply with a number of requirements. First of all, do not allow the use of antennas of range and significant deviations from their basic azimuths. Eliminating cases of antennas, feeders which have a large asymmetry (20%) and attenuation (above 10 dB). To do this in a timely manner and in full control of the main operational and technical specifications. Connect symmetrical AFD to receivers who have unbalanced inputs, should be through the transition baluns. Otherwise, due to the appearance of the antenna feeder effect of distorted antenna patterns and reduced noise immunity radio.

In most cases, the required radio quality and reliability is achieved by using powerful transmitters on the radio link. Therefore it is necessary to practice the wider use of redundant dual-polarization and AFD for the organization of dual diversity reception in space or polarization. This will improve the reliability of radio communication, equivalent to that achieved at a magnification of 10 times the energy potential of radio.

In order to effectively use AFD on the stationary radio centers must constantly work to improve the skills of staff serving antenna systems and RF paths.

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