APPLICATIONS Horn antennas are widely used as satellite dishes and radio telescopes. Antennas 6 2. PARABOLIC ANTENNAS A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves.
Flu (influenza). Flu is usually infectious a day before symptoms start and remains infectious for about five to six days. Children and people with lowered immune systems may be infectious for a few days longer.
Influenza has a rapid onset and pronounced symptoms. After the influenza virus invades a personâs body, an incubation period of one to two days passes before symptoms appear. For most people flu symptoms begin to subside after two to three days and disappear in seven to ten days. However, symptoms like coughing and fatigue may persist for two or more weeks.