ABSTRACT
Rain affects propagation through the lower troposphere, where liquid raindrops attenuate electromagnetic waves. Path attenuation can be important on terrestrial and Earth-space links at frequencies above about 6 GHz (see Figure 1.16). The link margin needed to combat multipath fading on a terrestrial link works to protect the same path against rain fades. Depending on link design, rain attenuation on a terrestrial path may not be important at frequencies above 15 or 20 GHz. Multipath is generally not a problem on Earth-space paths, and rain may limit system availability at frequencies as low as 7 or 8 GHz, depending again on link design.
