Antennas are devices that focus energy in a particular direction similar to the way the megaphone focuses voice energy. Antennas can provide different radiation patterns depending on the design and application. How much the energy is focused in a given direction is referred to as Antenna Gain. A flashlight can help illustrate the principle. Some flashlights allow the user to adjust the beam of light that comes out by twisting the lens. The lens can either focus or spread the beam of light. When the lens is used to spread or diffuse the beam of light, the beam of light travels a shorter distance than when the lens is twisted in a direction that tightens the beam of light.