A new wearable RF plethysmography (RPG) sensor is developed to monitor wrist pulse rate and variability. System design, numerical simulations, fabrication and measurements were carried out to demonstrate the performance of the plethysmography sensor. The RF sensor detects not only pulse rate but also modulations within each pulse. Clear detection of three modulations indicate that the RF plethysmography signals can be used for diagnosing different health conditions. A cavity based H-slot antenna is designed as a near field sensor. Two transmit and receive architectures based on conventional coupler/power combiner and innovative differential LNA approaches are designed in order to improve sensitivity of pulse detection. Both these architectures are based on the principle of isolation of the reflected signal from the transmitted signal. It is observed that the present RPG sensors perform better than the commercially available PPG sensor. © 2016 IEEE.