A Realistic Look at Link Distances of 70-80GHz Links

A Realistic Look at Link Distances of 70-80GHz Links

There has been significant growth in backhaul products operating in millimeter frequency range recently. Being subject to rain attenuation, and because different environments can have different characteristic attenuations, careful and precise calculation of theoretical distances is critical.

Read More


4 Realities about Rain Fading in Microwave Networks

Image of a thunderstorm line (in dBZ) seen on ...

Image via Wikipedia

Rain fading (also referred to as rain attenuation) at the higher microwave frequencies (“millimeter wave” bands)  has been under study for more than 60 years. Much is known about the qualitative aspects, but the problems faced by microwave transmission engineers—who must make quantitative estimates of the probability distribution of the rainfall attenuation for a given frequency band as a function of path length and geographic area—remains a most interesting challenge, albeit now greatly assisted by computer rain models.

A surprising piece of the puzzle is that the total annual rainfall in an area has almost no correlation to the rain attenuation for that area. A day with one inch of rainfall may have a path outage due to a short period of extremely high localized rain cell intensity, while another day of rain may experience little or no path attenuation because rain is spread over a long period of time, or the high intensity rain cell could miss the microwave hop completely.

Over the years, we have learned a lot about deploying millimeter wave microwave hops for our customers:

  • Rain outage approximately doubles in each higher millimeter wave band, e.g. 18 to 23 GHz
  • Rain outage is directly proportional to path length—assuming a constant fade margin for each hop
  • Rain outage in tandem-connected short hops is the same as for a single long hop—if they have the same fade margin
  • Multipath fading in optimally aligned millimeter wave hops does not occur during periods of heavy rainfall, so the entire path fade margin is available to combat rain attenuation fades

More information about assessing rain-induced attenuation is available in our white paper, Rain Fading in Microwave Networks.

Read More


Subscribe to our newsletter