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.
People with the flu usually have a fever for two to five days. This is different than fever caused by other upper respiratory viruses, which usually resolve after 24 to 48 hours. Most people with the flu have fever and muscle aches, and some people also have cold-like symptoms (runny nose, sore throat). Flu symptoms usually improve over two to five days, although the illness may last for a week or more. Weakness and fatigue may persist for several weeks (table 1). Flu complications â Complications of influenza occur in some people; pneumonia is the most common complication.