Characteristics of Inonized Regions

Characteristics of ionized regions

     1.Total Internal Reflection of Radio Wave

Radio waves below 40 MHz are significantly affected by the ionosphere, primarily because radio waves in this frequency range are effectively reflected by the ionosphere. The E and F layers are the most important for this process. For frequencies beyond 40 MHz, the wave-tend to penetrate through the atmosphere versus being reflected.

A single skip of a radio wave using the ionosphere.

Radio waves are a form of electromagnetic energy. Their propagation depends heavily on environmental factors. Our knowledge of the atmosphere allows us to choose the best frequency and propagation path to communicate.

   2.  Formation of Skip Distance and Skip Zone

Sky  waves

The skip distance is the distance over the Earth's surface between the point where a radio signal is transmitted, and the point where it is received having travelled to the ionosphere, and been refracted back by the ionosphere. The signals leave the antenna and travel away from it, eventually reaching the ionosphere. Normally they will leave the earth at an angle called the angle of radiation. Whether it is low, i.e. almost parallel to the Earth, or high, i.e. at a high angle upwards, they will reach the ionosphere at some point.

Skip distance

The sky wave refers to the signal that travels away from the Earth’s surface towards the ionosphere. Unlike a ground wave it does not follow the contour of the ground, but instead it is directed towards the ionosphere.

The angle between the line of the sky wave signal and the Earth’s surface at that point may be shallow or steep.

    3. Formation of Sporadic E and Sporadic F

Sporadic E or (Es) layers are ionization enhancements in the ionospheric E region at altitudes usually between 90 and 120 km A characteristic feature of Es layers is that they are thin layers with 0.6–2 km thicknesses and 10–1000 km horizontal extension. The Es layer could also appear as a non-uniform wave layer, multiple layers occurring simultaneously and separated at 6–10 km, or as composition of irregular elongated clouds of intense ionization within the lower E region .

 

F region, highest region of the ionosphere, at altitudes greater than 160 km (100 miles); it has the greatest concentration of free electrons and is the most important of the ionospheric regions. The charged particles in the F region consist primarily of neutral atoms split into electrons and charged atoms. 

4.VHF  Band in Inonized region

The ionosphere typically neither reflects nor absorbs waves with VHF or higher frequencies, but passes them through to space. There are no reflections back to the ground, so there is no useful propagation between stations on the ground. VHF signals with frequencies above about 30 MHz usually penetrate the ionosphere and are not returned to the Earth's surface. E-skip is a notable exception, where VHF signals including FM broadcast and VHF TV signals are frequently reflected to the Earth during late spring and early summer.