An improved analytical model for RF-DC conversion efficiency in microwave rectifiers

In this paper, an improved analytical model for diode efficiency in microwave rectifier is presented. This model provides a simple calculation routine to determine the input power level at which the peak reverse voltage across the diode starts to exceed the diode breakdown voltage when the diode efficiency starts to decrease. After studying the origins of the power losses in a shunt connected diode rectifier carefully, closed-form equations are derived to calculate the diode efficiencies at various input power levels. A 2.45 GHz microwave rectifier is designed and measured. The experimental results agree well with the proposed model prediction.