Propagation & the Real World#
What happens after the signal leaves the board.
Once RF energy leaves the antenna, it enters a world of reflections, obstacles, absorption, and interference. Propagation is how electromagnetic waves travel through real environments β and understanding it is the difference between a link that works reliably and one that fails mysteriously at certain times or places.
Propagation behavior varies dramatically with frequency, distance, environment, and even weather. This section covers the physics and practical reality of getting signals from one point to another through open space.
What This Section Covers#
- Free-Space Path Loss β The baseline signal loss with distance, and why link budgets are the first step in any wireless design.
- Near-Field vs Far-Field β Two fundamentally different regions around an antenna, with different physics and different practical implications.
- Reflections, Diffraction & Multipath β How signals bounce, bend, and scatter in real environments, creating constructive and destructive interference.
- Indoor vs Outdoor Propagation β Why indoor RF is harder than outdoor, and what walls, floors, and furniture do to the signal.
- Frequency-Dependent Propagation β How propagation characteristics change dramatically across the spectrum, from HF to millimeter wave.
- Antenna Height & Placement Effects β Why physical placement matters as much as the antenna itself, and how Fresnel zones determine link reliability.
- Weather, Materials & Environment β Rain, trees, snow, and building materials all affect RF propagation in frequency-dependent ways.