Can Sail equipment interfere with customer WiFi routers?

Certain types of Sail equipment are using frequencies in the 5 GHz band that may also be used for WiFi. However, it is very unlikely for Sail equipment to interfere with the operation of WiFi routers used by residential or business customers. This article explains why. 

A directional antenna transmits and receives signals only in specific directions. An omni-directional antenna transmits and receives signals equally in all directions. Sail's radio devices are installed on rooftops and are using directional antennas to target the radio signals as desired. Transmitting from such antennas toward the ground or toward the sky would be a waste of the available signal power. In contrast, WiFi routers have antennas that can be best characterized as omni-directional. Because WiFi devices may be located anywhere inside a residence or office (e.g. on a lower floor, on a higher floor, or behind a wall), WiFi antennas cannot be directional. As a result, Sail equipment installed on rooftops and operating in the 5 GHz band does not cause interference on WiFi routers located indoors, even if using exactly the same channel. The signal from Sail's antenna is too weak in the direction where the WiFi routers are located, and is further weakened by roof and floor materials. 

There is an additional reason why Sail equipment cannot interfere with WiFi routers. Consumer-grade WiFi routers use only certain parts of the 5GHz band, and specifically the UNII-1 and UNII-3 sub-bands shown in the below diagram. Sail equipment is in most cases configured to use the UNII-2a and UNII-2c sub-bands in order to entirely avoid interference to or from consumer-grade WiFi routers. 

Radios operating in the UNII-2a and UNII-2c sub-bands are required to implement Dynamic Frequency Selection (DFS), also known as Radar Avoidance. A radio detecting a radar signal at its operating frequency must change its channel to one not affected by radar. Consumer-grade WiFi routers do not implement DFS and consequently do not operate in the UNII-2a and UNII-2c sub-bands. As a result, Sail equipment is (with few exceptions) operating in channels that are different from those used by WiFi routers.