In the datasheets, 1.7 is stated as the peak forward voltage.A continuous forward current of 20 is the maximum consumption of this device.RF diode is necessary to operate the device at a DC reverse voltage below 400.
BYV34-400M Features
the forward peak voltage is 1.7
BYV34-400M Applications
There are a lot of TT Electronics / Semelab BYV34-400M applications of RF diodes.