Transmission Impairments

Factors that degrade the quality of signal during transmission.

Free Space Loss

Attenuation due to spread of the signal over large area.

Free space loss=PtPr=(4πfdc)2\text{Free space loss} = \frac{P_t}{P_r} = \left(\frac{4\pi f d}{c} \right)^2
Here:
PtP_t
Power at transmission
PrP_r
Power at reception
ff
Frequency of the signal
dd
Distance between attennas
cc
Speed of light in vacuum
LDB=20log⁡10(4πfdc)L_{\text{DB}} = 20 \log_{10} \left(\frac{4\pi f d}{c}\right)

Multipath Interference

When multiple copies of the signal reach the receiver with different delays. Caused because of reflection from obstacles.

In microwave, signal may refract and also go through curve paths so that it will reflect from ground.

Written by November 3, 2026 1 min read
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