Dual-axis Antenna Systems - Azimuth Travel: 180° ?

[john_robot]

Hi, I checked on Dual-axis Antenna Systems most of them have Azimuth Travel: 120°. why not 180° ?

http://www.servsat.com/_pdfs/1 VIKING Antennas-3.0m 3.4m 3.7m C and Ku Band.pdf

 

[SatelliteAV]

It is impossible to view satellites that are located 90 degrees from the downlink location. If we lived on a flat planet, this would be possible, but not on a globe.

It seems that a standard would be 140 degrees as that is closer to the range of viewable satellites.