In the datasheets, 1.1 is stated as the peak forward voltage.In order to operate efficiently, this device should have a peak RMS reverse voltage range of 420.
TS20P05G C2 Features
the forward peak voltage is 1.1 the peak RMS reverse voltage range of 420
TS20P05G C2 Applications
There are a lot of Taiwan Semiconductor TS20P05G C2 applications of RF diodes.