is there any simulator tools for radar?

ADS is really commonly used. Depends what part you want - more on the EM/antenna side just use any standard EM tool like HFSS/CST MWS, etc. If you're looking more at the circuit level use ADS and momentum, get some good nonlinear simulation performance there.

is the ADS capable of simulating the radar and the target? i use MATLAB.Which one is better?