 # What does the term LOS communication mean? Name the types of waves that are used for this communication. Which of the two-height of transmitting antenna and height of receiving antenna can affect the range over which this mode of communication remains effective? Verified
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Hint:Line of sight (LOS) is a type of propagation that allows data to be transmitted and received only when the transmit and receive stations are in direct line of sight with no obstruction between them. Line-of-sight communication includes FM radio, microwave, and satellite transmission.

Complete step-by-step solution:
The term "line-of-sight" refers to the distance between two points. Waves travel in a direct path from the source to the receiver, which is a feature of electromagnetic radiation or acoustic wave propagation. Light emissions travelling in a straight line are included in electromagnetic transmission. The atmosphere and material barriers can diffract, refract, reflect, or absorb the rays or waves, so they can't travel over the horizon or behind impediments.
Space waves and ground waves are used for the (LOS) communication because these waves can move directly from the earth's surface to the troposphere's surface, they are also known as tropospheric propagation. Because the signals are carried in a straight path from the transmitter to the receiver, it is also known as line of sight propagation.
The maximum line of sight distance ${d_m}$ (i.e., range of communication) between transmitting antenna of height ${h_T}$ and receiving antenna of height ${h_R}$ above the earth is given by
${d_m} = \sqrt {2R{h_T}} + \sqrt {2R{h_R}} \\ \\$
From this relation, it is clear that ${d_m}$ depends on both, ${h_T}$ and ${h_T}$ .

Note:Propagation along a line of sight might be advantageous. Radars utilise it to determine the distance between objects. The time it takes for the echo to return is measured after a radio pulse is directed towards the target. The object's distance is then calculated as half the product of this time and the radio wave's velocity.