In this paper, experimental result using a 5.8 GHz Doppler radar to monitor the variations of vital signs of an infant simulator under different medical conditions is presented. The infant simulator can mimic cardiovascular derangements seen in critically ill infants. The result demonstrates the system is capable of tracking a majority of the changes in heart rate and respiratory rate. Analysis suggests possible techniques for further improvement, such as direct coupling circuit, carrier frequency tuning and spectral analysis.