They say the cold war period was difficult. It got to strange things. It is known that the Russian and a number of American channels use circular polarization( usually left), while Europe applies horizontal. It would seem that there is no connection with the cold war. But it was worth assessing the independent installation of a satellite dish. It turned out that for European channels, when calculating the location and orientation of a satellite dish, the factor of polarization angle is important.
Cold War and heavy legacy in the orientation of satellite antennas
Satellites are known to hang above the equator. Special stations on Earth ensure that the vehicles do not move relative to the surface and do not rotate. The slightest deviations are fixed by special instruments of orientation in space, and subtle disagreements are quickly eliminated. Astronomers are worried about the question of how spacecraft can hang above the Earth if they are motionless. The Earth is rotating, but the satellites are forced to move to save the location. And with a decent speed, because they have a rather big orbit radius.
Already said in the reviews that the centrifugal force at this height balances the force of gravity of the planet, and the height of the satellites above the equator is the same. Only on this line of circular orbit fly and at the same time remain in place. Part of the satellites is inconvenient to catch a plate. To balance the force of attraction by centrifugal force, the vectors must act in opposite directions. The first acts down, the second - up.
This is possible if we move over the equator( not counting the errors in the difference between a geoid and a sphere).There, the satellites fly under the action of inertia, they rarely have to turn on adjustment engines in order to remain stationary relative to the Earth. Not always broadcasting spacecraft demonstrated a similar appearance. There were times of the Cold War, when paranoia made people spy on each other.
How will a satellite spy without changing its location? We flew in an elliptical orbit to photograph enemy territory. Why not just hang a pair of movie cameras over the Pentagon over America? Satellites would shoot down ballistic missiles. War could get hot. And so for the fast moving apparatus is difficult to keep up. True, the pictures were blurry. This paranoia brought that today in the world there are two types of polarization and, of course, converters( irradiators) for satellite antennas:
- Calculated for circular polarization.
- Designed for linear polarization.
Application mentioned above. Moving in an elliptical orbit, one of the satellite building axes is perpendicular to the Earth. With respect to a certain point, the spacecraft leans alternately on both sides, flying out of the horizon and flying over the horizon. It is not possible to use linear polarization, as the angle changes. The plates had to constantly track the movement of the satellite to download spyware, repeating the celestial trajectory, in addition, the angle of inclination would have to be changed.
It seemed difficult and irrational, so much so that they sacrificed a small loss of power from circular polarization, but the antenna aims more easily. Therefore, the audience of NTV + or Tricolor TV did not hear that people in Europe are suffering, rotating the converter along the axis. This information is important to know when installing a satellite dish with your own hands.
Russian channels, like a number of American ones, use circular( usually left) polarization, with which it is possible to precisely aim the dish at the satellite. In Europe, three degrees of freedom, which will save on energy. For a long time, Eutelsat satellites could not receive information - linear and circular polarization are incompatible. Antenna converters are different. Those who accept only linear polarization happen with a single emitter, a circular one, in principle, cannot be qualitatively accepted. It is believed that the owners of NTV + would like to be surrounded by competitors from Europe.
Approval seems doubtful. The circular converter differs from the linear one by and large by the presence of a depolarization plate. This can be seen on video in Youtube, if you type the query "converters with circular polarization."
Review dedicated to the topic of how to change the direction of polarization and make a linear circular. But if you pull the dielectric plate out of the converter, linear polarization will begin. Combined feeds, capable of capturing both species, are already on the market. And now information about the rules of installation of satellite dishes!
How to use correctly the ability to change the polarization of the converter to configure the antenna
We want to say that there is no protection. Sometimes polarization is required to change. Without this, self-installation of a toroidal antenna would not be so effective. The signal in them is reflected twice, due to which the polarization is reversed. In this case, the converter from a conventional satellite dish is adapted to receive, if you pull out the dielectric plate and, turning 90 degrees, return to its original place.
Remember, factory plastic often cracks. Replaced, for example, a credit or discount card grocery store or bank. We'll have to make a plate of two layers, since the material is thin. You can buy and install a toroidal-type satellite dish, then supplement it with conventional emitters, taken from an old dish, or in a workshop.
The main feature of the converter with circular polarization is two perpendicular rods inside. To look under the airtight lid, heat in boiling water, but do not immerse the housing with electronics and connector. Exceptionally round plug. Then gently removed by hand and cloth. A number of linear converters - the only rod.
Providers sell equipment tuned to a specific signal. But, knowing the above theses, it becomes possible for everyone to change the installation rules for satellite dishes. It is required to know that satellite broadcasting is conducted in two bands, C and Ku. Not any converter will block all waves. Created, however, hybrid, suitable for any occasion, if properly set the polarization. The installation scheme of a satellite dish should take into account such trifles. It is supposed to understand the types of polarization and frequency of reception. Then the correct installation angles of the satellite dish will lead to a wonderful video reception.
Next, you need a calculator that calculates the position of the spacecraft in the sky. There is in the form of a special program, or it is possible to do calculations online on any site.
The calculation of the satellite dish installation includes finding the elevation angle and azimuth of the dish, the height of the equipment is neglected in this case. As mentioned above, the Russian providers use circular polarization, so the slope of the irradiator, issued by calculators, is simply discarded. The installation location of the satellite dish is literally chosen by eye. With the help of a protractor and a compass, and the corners are already available from the calculator. It is necessary that a satellite hanging in space be visible at the reception point.
Installation of satellite dishes on the roof begins with the work of a punch, they need to make a couple of holes for the bracket. Next plate is positioned in the approximate direction of reception. The installation of the Yamal satellite dish( free television for Siberia) is conducted according to the signal quality. It is possible to immediately view the first program if there is a suitable receiver.
Satellite dish installation companies use special devices to assess the signal level, but ordinary citizens will have to navigate through the software of the equipment. There are special menus, through them you can observe the quality of reception. If the installation is done correctly, repair of satellite antennas is not required. It is important to equip a properly equipped lightning rod nearby.