How does pin-diode limiter in TR-cell work?

Hi all, in radars after the TR-cell there is usally a PIN-diode limiter.
Before the incoming wave meets the pin-diode, some of its power is coupled into a schottky diode for making a DC-voltage. This DC-voltage is applied to the PIN-diode and will bias it more or less depending on how much power ther is in the incoming wave.

My questions:
i. Is the PIN-diode, which is put in the middle of the waveguide, forward-biased or backward biased for a DC-steered attenuation ?

ii. There should be a capacitor to ground somewhere between the rectifying diode and the PIN-diode. Why can't I see it ! ? Do I have a capacitor in the structure between the diodes that is enough ?

regards,
StoppTidigare