Microwaves propagate through the atmosphere primarily by line-of-sight transmission, meaning they travel in straight paths from the transmitter to the receiver. Here’s how they behave as they move through the air:
- Straight-Line Travel:
Because of their short wavelengths, microwaves don’t bend much around obstacles like hills or buildings, so clear paths between antennas are usually needed. - Atmospheric Absorption:
Certain atmospheric gases, especially water vapor and oxygen, can absorb microwaves at specific frequencies, causing some signal loss over long distances. - Scattering and Reflection:
Microwaves can be scattered or reflected by particles such as raindrops, clouds, or dust, which can affect signal strength and quality, especially in bad weather. - Minimal Diffraction:
Unlike lower-frequency radio waves, microwaves have limited ability to diffract (bend) around obstacles, so obstructions can block the signal. - Tropospheric Effects:
Under certain atmospheric conditions (like temperature inversions), microwaves can travel farther by bending slightly—a phenomenon called tropospheric ducting.