A satellite dish is used for two purposes: to send signals towards the signal receiver or to receive signals from the space satellite. Even though the overall design is the same for all satellite dishes, there are differences depending on the usage. A satellite dish usually transmits signals for radio or TV or Internet.
A satellite dish is constructed out of many parts. There is the metallic dish, parabolic in shape, which receives the signal, the feed horn, which starts from the center of the dish and points in the exterior, the arm of the dish that supports the feed horn etc.
The satellite dish is only a part of an entire satellite system. The dish captures the signal transmitted by the satellite and sends it to the receiver. When we talk about signals, we actually talk about electromagnetic waves. There is an LNB that transforms these electromagnetic waves into electrical signal. This way they can be sent to the signal transmitter. From there the signal travels to the L-band range. When the signal receiver catches these signals it transforms them into television images and sounds.
To install a satellite dish you have to take into consideration some factors. First is the location of the dish. You have to place the dish in a way that the signal will have no obstruction in its path to the receiver. This means no trees, no buildings, nothing. After that it is important to align the antenna at the proper angles. The antenna has to be grounded also for safety reasons.
The larger the dish, the better the image quality. This is how things evolve today. Still, this is not a mandatory thing as there are small dishes that provide amazing quality.