Radio Wave Propagation Essay Example | Topics and Well Written Essays - 1500 words

Radio Wave Propagation - Essay ExampleSo waves get strength rapidly. 1Radio waves travel very fast but only in a straight line. Thus the curvature of the earth should limit the outer space between transmitter and receiver, a distance of close 60 miles 100 km). However, the earths atmosphere has properties that allow enhanced propagation. The atmosphere is layered, and these layers have important effects on waves that are propagated on the earths surface. The layer called the troposphere is a heavy, oxygen filled layer that extends from the surface to about 30 miles (50 km) altitude. From 30m (50 km) to 260m (416 km) is a highly charged layer called the ionosphere. The ionosphere affects intercommunicate signals in different ways depending on their frequencies. 2The frequencies used for radio propagation range from 30 kHz to 3 GHz. Frequencies are continuous but are defined in bands according to their properties and uses. Higher frequencies have shorter wave lengths and much en ergyLF waves are propagated as ground waves which, as the name implies, travel on the ground. Because the ground and its terrain interfere with ground waves, transmission requires lots of power. LF waves are used mainly in maritime communications over the sea and the navigational dodging called LORAN. 4 Sometimes ground waves suffer from a reflecting wave off the ionosphere that can return to earth out of phase near the receiver and interfere with the straightaway reception.MF wave frequencies are used for AM radio broadcasting. They are also ground waves and during the daylight hours are limited to a range of about 60 miles (100 km). But radio waves can be bent or refracted by changes in the earths atmosphere particularly by weather patterns and by the ionosphere. The Ionosphere consists of the D (30-60 miles 50-100 km), E (60-100 miles 100-160 km), F1 (90-160 miles 144-256 km), and the F2 (160-250 miles 256-400 km) layers. At night, the E layer disappears and the F1 and F2 laye rs combine to form the F layer (somewhere between 90 and 250 miles 144-400 km). Since the E layer disappears at night, the lower relative frequency Sky Waves (MF) travel further up into the atmosphere, where they are REFRACTED by the F layer up to 300m. Thats why at night, your radio often picks up many another(prenominal) more AM broadcast stations 4HF waves have enough energy to reach the ionosphere during the day and are refracted by its various layers. Thus short-wave can travelled much further than the curvature of the earth would normally allow. This Sky Wave propagation depends strongly on the ionosphere which is in constant flux. The ionosphere is affected by many astronomical events like meteor showers and solar flares it is also affected by seasons. Because the ionosphere changes so much, short-wave is considered unreliable for important commercial use. However, some of the effects on radio transmission are positive. These so-called anomalous propagations are of