2-36distances are possible because of the different densities and refractive qualities of warm and cool air. Thesudden change in density when a radio wave enters the warm air above a duct causes the wave to berefracted back toward Earth. When the wave strikes the Earth or a warm layer below the duct, it is againreflected or refracted upward and proceeds on through the duct with a multiple-hop type of action. Anexample of the propagation of radio waves by ducting is shown in figure 2-25.Figure 2-25.-Duct effect caused by temperature inversion.Q42. How do raindrops affect radio waves?Q43. How does fog affect radio waves at frequencies above 2 gigahertz?Q44. How is the term "temperature inversion" used when referring to radio waves?Q45. How does temperature inversion affect radio transmission?TROPOSPHERIC PROPAGATIONAs the lowest region of the Earth's atmosphere, the troposphere extends from the Earth's surface to aheight of slightly over 7 miles. Virtually all weather phenomena occur in this region. Generally, thetroposphere is characterized by a steady decrease in both temperature and pressure as height is increased.However, the many changes in weather phenomena cause variations in humidity and an uneven heating ofthe Earth's surface. As a result, the air in the troposphere is in constant motion. This motion causes smallturbulences, or eddies, to be formed, as shown by the bouncing of aircraft entering turbulent areas of theatmosphere. These turbulences are most intense near the Earth's surface and gradually diminish withheight. They have a refractive quality that permits the refracting or scattering of radio waves with shortwavelengths. This scattering provides enhanced communications at higher frequencies.Recall that in the relationship between frequency and wavelength, wavelength decreases asfrequency increases and vice versa. Radio waves of frequencies below 30 megahertz normally havewavelengths longer than the size of weather turbulences. These radio waves are, therefore, affected verylittle by the turbulences. On the other hand, as the frequency increases into the vhf range and above, thewavelengths decrease in size, to the point that they become subject to tropospheric scattering. The usablefrequency range for tropospheric scattering is from about 100 megahertz to 10 gigahertz
Propagation of disturbance suffered by a particle in a medium is called wave propagation Wave Propagation is a term used to estimate the actions and characteristics of a wave of motion either in solids, liquids, gasses, or electrical radio type waves by the environment it is in and what factors affect those waves behaviors.
A Sound wave, water wave, earth quake wave. Electromagnetic waves (radio, light, etc.) do not require a medium for propagation.
In a transverse wave the particle displacement is perpendicular to the direction of wave propagation (at right angles). In a longitudinal wave the particle displacement is parallel to the direction of wave propagation.
A longitudinal wave is a scalar wave with the vibration parallel to the central direction of propagation.
Wave is a propagation of oscillations of some physical parameter (perturbation of pressure, mass density, electrical or magnetic fields...). If oscillations are perpendicular to the direction of propagation - the wave is transverse (for example - electromagnetic wave). If physical parameter oscillates along the propagation direction - the wave is longitudinal(Sound).
Lucien Boithias has written: 'Radiowave Propagation' -- subject(s): Tropospheric radio wave propagation
Ground wave, sky wave and space wave propagation
Wave propagation
Propagation of disturbance suffered by a particle in a medium is called wave propagation Wave Propagation is a term used to estimate the actions and characteristics of a wave of motion either in solids, liquids, gasses, or electrical radio type waves by the environment it is in and what factors affect those waves behaviors.
A Sound wave, water wave, earth quake wave. Electromagnetic waves (radio, light, etc.) do not require a medium for propagation.
Space wave propagation frequency is nothing special, it is the same frequency of the wave in question, for example WLAN Wifi produces 5.2 GHz radio wave from your computer or from router, so that would be the the space wave propagation frequency in question
... wave's speed of propagation.
"Propagation" means the process of the wave getting from here to there.
Frequency and speed of propagation of the wave are independent of one another. The medium determines the speed of propagation.
In a transverse wave the particle displacement is perpendicular to the direction of wave propagation (at right angles). In a longitudinal wave the particle displacement is parallel to the direction of wave propagation.
Sound molecules traveling through air is an example of a longitudinal wave. It moves parallel to the direction of wave propagation.
A longitudinal wave is a scalar wave with the vibration parallel to the central direction of propagation.