...under perpetual construction.
I have seen a suggestion from W8JI to connect two PIN diodes in parallel for the RF but in series for the DC, with the anode and cathode reversed in one diode (so actually in "anti-parallel") to futher reduce the distortion.
S-parameters measured at -20 dBm
Diode forward biased with currents from 1 mA to 100 mA.
Diode reverse biased with voltages from 0 V to 20 V.