13 LENSES, DISHES, AND ANTENNA ARRAYS
Lenses, dishes, and antenna arrays are all devices that can be used to concentrate and focus electromagnetic radiation. Furthermore, because these devices can isolate radiation from a specific direction, they can be used to create images or photographs.
Dishes used for microwave transmission and reception are a good example to start with. Dishes are often used to receive microwave transmissions from satellites, such as those used for satellite television reception. The main purpose of the dish is to concentrate the microwaves, thus increasing the signal strength. The dish must be made of a reflective material; metal materials are used for radio and microwaves because metals reflect quite ...