Understanding Mobile Radio Propogation-2 — Lesson 2

This lesson covers the three primary propagation mechanisms: reflection, diffraction, and scattering. It delves into the details of how radio waves propagate, and how these mechanisms affect the propagation of radio waves. The lesson also discusses the importance of understanding these effects when developing a realistic channel propagation model. For instance, it explains how reflections occur when electromagnetic waves impinge on an object with a large dimension compared to the wavelength. It also explains how diffraction occurs when the radio path between the transmitter and receiver is obstructed by a surface with sharp irregularities. Lastly, it discusses scattering, which occurs when the medium has objects that are smaller or comparable to the wavelength. The lesson uses the example of a base station communicating with a mobile station to illustrate these concepts.

Video Highlights

01:18 - Introduction and recap of previous lessons, including propagation basics and properties of radio waves
03:08 - Explanation of diffraction, which occurs when the radio path between the transmitter and receiver is obstructed by a surface with sharp irregularities
06:20 - Explanation of the Fresnel coefficient gamma and how it relates to the electric field intensity of the reflected and transmitted waves
13:06 - Explanation of the two-ray ground reflection model and its importance in predicting large scale signal strength over several kilometers
28:22 - Discussion on the concept of diffraction and its importance in wireless communication
33:37 - Explanation of the Fresnel-Kirchhoff diffraction parameter and how it can be used to calculate the diffraction gain
41:59 - Discussion on the concept of scattering and its importance in wireless communication
49:01 - Summary of the lecture and conclusion

Key Takeaways

- Reflection, diffraction, and scattering are the three primary propagation mechanisms that affect the propagation of radio waves.
- Reflections occur when electromagnetic waves impinge on an object with a large dimension compared to the wavelength.
- Diffraction occurs when the radio path between the transmitter and receiver is obstructed by a surface with sharp irregularities.
- Scattering occurs when the medium has objects that are smaller or comparable to the wavelength.
- Understanding these effects is crucial when developing a realistic channel propagation model.