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.
Although infections from other viruses may have similar symptoms, those due to the influenza virus tend to be worse. Symptoms can begin about 1 to 4 days, or an average of 2 days, after a person is first exposed to the influenza virus.Fever and other symptoms can usually last up to 7 to 10 days, but the cough and weakness may last 1 to 2 weeks longer.If you get sick with influenza, home treatment can help ease symptoms.lthough infections from other viruses may have similar symptoms, those due to the influenza virus tend to be worse. Symptoms can begin about 1 to 4 days, or an average of 2 days, after a person is first exposed to the influenza virus.