What is defined as the weakening of signal amplitude as the signal passes through a medium?

Attenuation is the reduction in the amplitude and intensity of a signal as it travels through a medium. In wireless communications, this weakening occurs due to the signal spreading out over distance (free space path loss) and being absorbed by obstacles like walls, furniture, and even air. It is a fundamental property of signal propagation and is measured in decibels (dB). The further a signal travels or the denser the medium it passes through, the greater the attenuation and the weaker the received signal.

A. Diffraction: This is the bending of radio waves as they pass around the edge of an obstacle, not the weakening of the signal itself.

B. Reflection: This occurs when a radio wave bounces off a surface that is large relative to the signal's wavelength, changing its direction.

D. Scattering: This happens when a signal strikes an uneven surface with dimensions smaller than the wavelength, causing the signal to reflect in multiple directions.

1. Coleman, D. D., Westcott, D. A., & Harkins, K. A. (2021). CWNA Certified Wireless Network Administrator Study Guide (6th ed.). Wiley. Chapter 3, "Radio Frequency (RF) Fundamentals," p. 88, states, "Attenuation is the weakening of an RF signal as it travels. Another term for attenuation is loss."

2. Kurose, J. F., & Ross, K. W. (2021). Computer Networking: A Top-Down Approach (8th ed.). Pearson. Chapter 7, "Wireless and Mobile Networks," Section 7.1.2, describes how signal strength diminishes with distance (a form of attenuation) and as it passes through matter.

3. Stallings, W. (2016). Data and Computer Communications (10th ed.). Pearson. Chapter 5, "Signal Encoding Techniques," Section 5.1, explains that "the signal strength falls off with distance over any transmission medium. For guided media, this is generally exponential and is typically referred to as attenuation." This principle is directly applicable to unguided (wireless) media.