How to measure noise figure?

I want to measure a noise figure of diode detector to estimate losses at receiver.
How do i do it? Picture is included.

Hi:

you can mesure the amplitude of output noise when you turn of the input signal and then calculate the output noise power from multipling the output niose amplitiude in itself .
then you can compute the noise figure from this equation :

Noise figure = (SNR)in/(SNR)out = (Sin/Sout)×(Nout/Nin)

Noise figure = (1÷Gain)×(output noise amplitude^2)÷(kTB);

where B is the bandwidth of your circuit and k is the bultzman constant and T=300k

good luck.