Radiation and Propagation of Waves

Extraterrestrial Communications

Extraterrestrial Communications: Extraterrestrial Communications : The most recent, and by far the fastest-growing, field of communications involves the use of various satellite relays, of which the first was launched in 1957,-12 years after the practicability and orbital positioning of stationary satellites were first described and calculated. The field may be subdivided into three parts, each …

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Tropospheric Scatter Propagation

Tropospheric Scatter Propagation: Tropospheric Scatter Propagation is a means of beyond-the-horizon propagation for UHF signals. Tropospheric Scatter Propagation uses certain properties of the troposphere, the nearest portion of the atmosphere (within about 15 km of the ground). Properties of Tropospheric Scatter Propagation: As shown in Figure 8-20, two directional antennas are pointed so that their …

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Sky Wave Propagation Frequency Range

Sky Wave Propagation Frequency Range: Sky Wave Propagation Frequency Range is the  ionosphere is the upper portion of the atmosphere, which absorbs large quantities of radiant energy from the sun, becoming heated and ionised. There are variations in the physical properties of the atmosphere, such as temperature, density and composition. Because of this and the …

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Electromagnetic Spectrum

Electromagnetic Spectrum: In an earth environment, electromagnetic waves propagate in ways that depend not only on their own properties but also on those of the environment itself; some of this was seen in the preceding section. Since the various methods of propagation depend largely on frequency, the complete electromagnetic spectrum is now shown for reference …

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Interference of Electromagnetic Waves

Interference of Electromagnetic Waves: Interference of Electromagnetic Waves occurs when two waves that left one source and travelled by different paths arrive at a point. This happens very often in high-frequency sky-wave propagation and in microwave space-wave propagation. It occurs when a microwave antenna is located near the ground, and waves reach the receiving point …

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