Microwave detection circuit verification
Your coil won't be responsive at the frequencies you are interested in.  I don't have the math to figure it, but I have some experience as a technician with radio frequency circuits.  That coil on that core will probably do a dandy job of filtering microwave signals out of your receiver.
Those diodes probably won't work at microwave frequencies, either.  The BAT43 datasheet only mentions frequencies twice: 1MHz and 45MHz.  That diode isn't made for GHz frequencies like you will need to detect microwaves.


You need a better diode.  I have used the BAT63 for a similar project.
You need an antenna instead of that coil.  I used a simple dipole antenna.  Just two equal length wires of approximately 1/4 the wavelength of the operating frequency you are interested in.

The circuit that I built used a sort of voltage multiplier to drive a few LEDs to indicate the RF level.
It looked like this:

You could simplify it to this:

Use two wires of about 3 centimeter length as antennas connected to P1 and P2.  3 centimeters is approximately correct for 2.5GHz.  That's about 1/4 the wavelength of 2.5GHz.