Microwave Radiometer simulation in ADS

Hi Guys,

I need your help to check my system simulation model. it is a total power radiometer...it works between 10 to 12 GHz and input signal of the system is just noise with certain temperature 80°C. I want to simulate the system in time domain (input and output signals) and frequency domain (spectrum signals and power spectral density)...Actually my experience in ADS is not enough...so I need your help to choose which simulator in ADS that can be used (Transient, AC, Envelop, HB...etc) ...I have attached the file of system model

Thanks in advance