Satellite dish

A parabolic antenna for the satellite broadcast reception, often called satellite dish that receives radio programs such as radio, television or other services such as Internet access via satellite, to be broadcast from a satellite in a geostationary orbit. Due to the large distance of about 36,000 km, the signals on the earth are very weak. To receive it, parabolic antennas are needed with a diameter of typically 60 cm, for example, for the Astra satellites at Ku - band.

• 4.1 Germany
• 4.2 Austria

Construction

The antenna consists of a parabolic mirror and the reception head with horn antenna, integrated frequency converter and IF amplifier (low noise block converter, LNB ). The parabolic reflector concentrates by reflection the signal waves at its focus. There is the receiving head, processes the signals. Depending on the design conduct one or more coaxial cables, the received signals to a receiver or distribution system ( " satellite system " ) on.

The parabolic mirror

The size of a parabolic antenna is indicated by the diameter of the parabolic mirror. The most common types of antennas have a diameter of 60 to 120 cm. The surface and thus the received energy grows quadratically with the diameter. For example, the receiving surface of a 85 cm antenna is twice as large as that of a 60 - cm dish. Unlike the terrestrial transmission frequencies in the VHF or UHF band, the Ku-band radiation is markedly attenuated by moisture. The signal strength may decrease by more than 6 dB. When installing two or more LNBs ( multi-feed ) larger antenna diameter are recommended.

Offset antenna

The (now almost exclusively used ) offset antenna is basically part of a rotationally symmetric parabolic antenna. The mirror surface is not circular, but oval. In contrast to the rotationally symmetric parabolic antenna "looks" the offset antenna, not directly to the satellite, but has a significant angular deviation (offset angle) on. LNB requires the same angular deviation in the other direction so that it is still in the focal point of the antenna level.

The advantage of this form of antenna LNB no longer hangs in the input beam, so it is lost no reception energy. Also, the reflector has dimensions slightly cheaper. Since the reflector offset antenna is a vertical than in a same orientation symmetric parabolic antenna to snow and dirt collect not so easy on the reflector.

Unfortunately, ( here called α ) by the offset angle as the difference angle in comparison with a rotationally symmetrical parabolic antenna, the effective area of the parabolic reflector about to cos ( α ) smaller but this is offset by the elliptical shape of the antennas offset again.

Material

Parabolic exist today mostly in painted steel or aluminum. These paints or powder coatings are used by the manufacturers. Adhesive films and synthetic resin paints are not suitable because they introduce an additional attenuation in the receive path. The varnish is always matte, otherwise the sunlight would be reflected bundled on the LNB when the sun is behind the satellite. Plastic mirrors are rarely used because of higher prices. For them, a metal grid in the plastic is incorporated, which reflects the radiation. Unlike aluminum mirrors, the fixing screws do not pass through the mirror surface, but the plastics material is on the back of the mirror in the form of a bracket above. The plastic can be any color or be transparent, so that the antenna is hardly noticeable on facades. Furthermore, there are wire mesh antennas. Their advantage is that they make the wind only lower (but not negligible ) resistance, their disadvantage is the risk of rust in paint damage. They are usually painted black to be inconspicuous.

The receiving head (LNB)

At the focal point of the parabolic mirror is the reception head. For the reception of satellite programs with relatively small antennas in Europe, the Ku-band (10,7 to 12.75 GHz ) is being used. The gain of the satellite signals is carried out by low noise block converter (LNB, rarely LNC). This converts the signal into a frequency range of 950 to 2150 MHz, this can receive a satellite receiver.

With the introduction of satellite technology is first introduced mainly LNBs ago that covered this time common frequency range from 10.95 to 11.7 GHz, to the max. 48 analog programs could be transferred. Later the area was used from 10.7 to 10.95 GHz for satellite reception. The entire range of 10.7-11.7 GHz is now called low band. The first satellite, which used frequencies below 10.95 GHz, was the Astra 1C.

Over time, the number of programs grew, and it proceeded to make use of the entire Ku band. The 'new ' frequency range from 11.7 to 12.75 GHz is designated as a high- band. These were developed LNBs, covering the entire frequency range. To identify this universal LNB are called. On the high- band digital stations are mainly emitted. However, this is historical and has no technical background. Send to a universal LNB, you can connect both analog and digital receivers.

The change started in 1996 from analog to digital TV DVB- S was completed about 2002/2003, only German programs were provisionally also aired similar to primary care, which was discontinued on April 30, 2012.

Special designs

Multifeedhalter

Normally, it is common to align satellite dishes directly at the satellite. However, since neighboring satellites can be received with an antenna, one uses " Multifeedhalter " to two (or more) to be attached to an antenna LNB, with multiple LNBs are firmly positioned in different foci of the satellite antenna ( per satellite LNB ). Since at least one LNB is not aligned in this case, the focal point is called such antennas also " cross-eyed mirror ".

Rotating antennas

If the use of several LNBs is too expensive, I implement a antenna mast motor and a polar mount bracket that the celestial equator departs on rotation on which are the geostationary satellites. Such systems are only suitable for a subscriber. A rotating, stationary satellite antenna can leave about 30 different satellite positions with television programs with a clear view to the south in Central Europe. In this way, theoretically usable bandwidth multiplied to more than 100 GHz. Special antenna rotors are available from 40 €, the installation requires some skill. Rotating systems with 1 meter dish size in Central Europe currently receive more than 6,000 radio and television programs, of which almost half is unscrambled.

Control commands for multi-feed and motorized systems are transmitted by DiSEqC commands.

" Invisible " antennas

For aesthetic or legal reasons it can be useful to hide a satellite dish. So can be hidden in the garden normal antennas for example, plastic tables on the balcony or in empty rain barrels, whose plastic transmits the microwaves.

In addition, there are various special designs, for example, as a chair, in which the backrest serves as a satellite dish, if no one is sitting on it. Another well-known alternative design is the flat antenna ( Panel Antenna ). Such special designs are not suitable for Multifeedhalter, but partially exist motor solutions.

Cabling

For wiring of the parabolic antenna, a coaxial cable with F- connectors used. It is recommended to use cable with multiple shielding (> 90 dB), and a small damping. It should be ensured that the inner conductor is not made of twisted copper wires, but of a whole copper strand.

Multi-party satellite solution

While single-family homes in the decision can be made quickly for a satellite dish, which is often difficult in MDU. Not infrequently, individual antennas may be attached to such objects only in special cases. Order, as shown in the picture to avoid individual antennas for optical reasons, different solutions for satellite broadcast reception systems ( also referred to as " satellite systems " ) have been developed which make do with a community antenna ( see also Digital Satellite Equipment Control):

• Satellite block distribution
• Cable system and, based on the reaction, for example by the " unicable " system
• Canal preparation
• Feeding into the home network

Pay fees in Germany and Austria

In January 1991, the Federal Ministry of Posts and Telecommunications said that it was no longer necessary to log parabolic antennas for the reception of radio and television programs of communications satellites as part of a single fee authorization by the Authority. The installation and operation of parabolic mirrors was thus permitting and free of charge.

The Austrian Postal and Telegraph Administration issued in 1991 a general authorization or release of the reception of radio and television transmissions via satellite.

Legal right of a tenant to a parabolic antenna

Germany

The landlord needs to tolerate no exposed cables or antennas on the building facade. In addition, the landlord has an interest as owner of the house in a single, unbroken facade design, because that gets the value of the house. The landlord has set a voice from his right to the leased out where the satellite antenna is to be mounted, if the antenna is installed by screws.

Even if it does not allow the lease to install a satellite dish on the building façade, a tenant has a legal right to attach a satellite dish, if he has a special interest in receiving additional channels which can not be received over the existing offer including additional offers ( pay TV) can be detected. This can for example apply to foreign tenants or journalists.

The Federal Constitutional Court ( decision of 31 March 2013 1 BvR 1314/11 )

" Reaffirms the principles that must be observed in civil or commercial dispute concerning the installation of satellite dishes by tenants. The civil courts have to make a case-specific assessment, in which the ownership interests of the landlord at the - also visually - undiminished maintenance of residential building, and information interests of the lessee are to be set on the use of generally available information. It should also be the interest of foreign tenants at the reception of radio programs from their home, including the special situation of linguistic and cultural minorities. "

Austria

After OGH GZ 5Ob199/03f one must in principle not restricted to certain offers can (eg, cable TV). However, there are certain limitations for tenants in terms of width and placement of the satellite dish, but the actual law, access to a satellite dish with the relevant offer (satellite) to get, do not bother.

Since the outer appearance of the building is changed, possibly general parts are claimed, one needs as a home owner and a potential landlord consent of the other owners. If the appearance is affected, they do not tolerate it. In problematic cases, you can seek court approval in uncontested proceedings.

Note also the local building code. In Vienna, you can submit an application for architectural review.