Define and briefly explain attenuation that happens during transmission due to c

Question

Define and briefly explain attenuation that happens during transmission due to conductor and dielectric losses. Find (reference the sources where you find this info) an actual coaxial cable specification and report its attenuation per foot (or other unit length). Find (reference the sources where you find his info) and report a plot the attenuation (Absorption) through rain versus frequency; discuss this plot, at what frequencies attenuation through rain peaks and what frequencies it is minimum. Define and briefly explain path loss that happens during wireless transmissions due to antenna radiation. Find (reference the source where you find this info) and present information due to antenna radiation. Find (reference the sources where you find this info) and present information on friis equation that describes path loss. Calculate path loss for an example of transmission between two antennas assuming that the gain of both antennas is 1. Define and briefly explain dispersion that happens, due to material properties varying with frequency. Name one material that has material properties that change with frequency and present any related data (reference the sources where you find this info).

Explanation / Answer

Attenuation Dielectric losses are caused by the electric field acting on the molecules of the insulator and thus, will cause heating through molecular agitation. Radiation losses are the loss of energy as the electromagnetic wave propagates away from the surface of the transmission line conductor.
Losses on long runs of commonly used coaxial transmission line causes concern as low as 400 MHz. Because of the increased losses the power handling capability decreases at higher frequencies, therefore, at higher microwave frequencies, or where long runs make transmission attenuation losses unacceptable, or where high power levels causes the transmission to overheat, waveguides are used instead of the transmission lines.
Attenuation due to conductor happens within the transmission cable arise from the resistance of the conductors and the current flowing in the conductors results in heat being dissipated. The actual area through which the current flows in the conductor is limited by the skin effect, which becomes progressively more apparent as the frequency rises. To help overcome this multi-stranded conductors are often used.

To reduce the level of loss due in the transmission cable, the conductive area must be increased and this results in low loss transmission cables being made larger. However it is found that the resistive losses increase as the square root of the frequency.

Attenuation (dB per 100 feet)

Coax Cable Signal Loss (Attenuation) in dB per 100ft*
Loss*   RG-174   RG-58   RG-8X   RG-213   RG-6   RG-11   RF-9914   RF-9913
1MHz   1.9dB   0.4dB   0.5dB   0.2dB   0.2dB   0.2dB   0.3dB   0.2dB
10MHz   3.3dB   1.4dB   1.0dB   0.6dB   0.6dB   0.4dB   0.5dB   0.4dB
50MHz   6.6dB   3.3dB   2.5dB   1.6dB   1.4dB   1.0dB   1.1dB   0.9dB
100MHz   8.9dB   4.9dB   3.6dB   2.2dB   2.0dB   1.6dB   1.5dB   1.4dB
200MHz   11.9dB   7.3dB   5.4dB   3.3dB   2.8dB   2.3dB   2.0dB   1.8dB
400MHz   17.3 B   11.2dB   7.9dB   4.8dB   4.3dB   3.5dB   2.9dB   2.6dB
700MHz   26.0dB   16.9dB   11.0dB   6.6dB   5.6dB   4.7dB   3.8dB   3.6dB
900MHz   27.9 B   20.1dB   12.6dB   7.7dB   6.0dB   5.4dB   4.9dB   4.2dB
1GHz   32.0dB   21.5dB   13.5dB   8.3dB   6.1dB   5.6dB   5.3dB   4.5dB

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