In this paper, an analysis of a Gunn loaded stacked annular ring microstrip antenna is presented using a circuit concept. Consequently, various parameters such as input impedance, voltage standing wave ratio, return loss, band width, radiation pattern, and beam width of the antenna are evaluated as a function of bias voltage for different threshold values. It is found that the operating frequency of the Gunn loaded stacked patch is controllable with the bias voltage. The band width of the Gunn loaded stacked patch is improved to 11.61% as compared to the 9.16% band width of the stacked patch in addition to there being better matching and wider tunability. The radiated power and beam width of the stacked patch are also enhanced by loading a Gunn diode with it.