Radio Wave Propagation#
Radio wave propagation refers to the behavior of radio waves as they travel between two points. Understanding the nature and effects of radio wave propagation is crucial for various applications in wireless communication.
The Sun and Its Influence#
Like light waves, radio waves undergo multiple phenomena: reflection, refraction, diffraction, absorption, polarization, and scattering. The effects of different conditions on radio wave propagation are essential to consider for:
- Selecting frequencies for international broadcasts.
- Designing robust mobile phone networks.
- Implementing radio navigation—a navigation type using radio signals to determine a device's position.
- Operating radar systems.
Light And Ultraviolet#
Both light and ultraviolet rays influence the ionosphere, affecting radio wave propagation.
Sunspots: The More, The Better#
Sunspots play a significant role in radio propagation. Their activity often correlates with enhanced radio wave propagation due to increased ionospheric reflectivity.
Line of Sight Propagation#
Image by F1jmm / CC BY-SA
In ideal conditions, line of sight propagation assumes a significantly tall antenna with no obstructions, like large mountains, in the signal path.
Image by Armageddons at Swedish Wikipedia / Public domain
However, real-world scenarios for VHF and UHF transmissions can be intricate. Factors like tree branches, rain, snow, or even non-line-of-sight objects can disrupt radio transmissions due to diffraction effects. For optimal propagation, the first Fresnel zone should remain obstruction-free.
Surface-reflected radiation, especially from the ground or saltwater, can amplify or nullify the direct signal. Elevating antennas can minimize this loss, a phenomenon called height gain. This topic's complexity has led to extensive research, resulting in comprehensive books and doctoral theses dedicated to propagation nuances.
When a direct visual fix is unattainable, it's crucial to account for the Earth's curvature when calculating line-of-sight paths on maps.