A satellite finder is a device used to detect the position of broadcast satellites when setting up a dish. This avoids the need to find the right location and angle for the dish by trial and error. The price of a satellite finder can vary immensely so it is important to be sure exactly what is needed and find an appropriate model.
Unlike a television aerial, which simply needs to be in range of a nearby broadcast tower, a satellite dish must be placed in a precise position and direction to pick up a signal. If it is even slightly out of position, it will fail to pick up a good signal, as anyone who has had a dish accidentally bumped by a tree branch will know. Because a satellite can cover an entire country rather than the small area covered by a broadcast tower, the precise positioning for a dish depends on its location.
A satellite finder helps discover the two important measurements which detail how a satellite relates to a location. One is the azimuth angle, which is the angle at which the satellite orbits the earth. This angle is in relation to the equator, not one's own location. The second measurement is the elevation, which is the angle between the satellite and an imaginary line running along the ground from one's location to the horizon.
Usually a satellite finder will be in the form of a handheld electronic device which has the details of major satellites built into it. It will instruct as to the correct angles at which to install the dish based on the location. It can then confirm correct installation. This is considerably easier than the traditional method of wiggling the dish about while a partner stands in front of the television and yells out when you've got it right.
In most cases, the more expensive a satellite finder, the more precise its measurements. The right model depends on your circumstances. Somebody who uses a dish on a motor home and needs to adjust it a couple of times a year may find a budget model suffices. A professional installer who sets up multiple dishes each day may need a premium model.
An alternative to a satellite finder unit is to use an online service. There are several sites which can use a specific address to provide a list of satellite locations in relation to a location. These sites can also tell someone the precise angle and positioning for a dish to get the best results. The drawback is that some form of measuring device is still needed to make sure to get the dish in this position.