Abstract This paper presents a differential capacitance sensor of variable area type. The principle of the sensor lies in that with the help of two phase difference of 180DEG of the excitation signal source act on the two fixed electrode, the pendulum’s moving sheet between the fixed moving sheet forms electric field.When pendulum in moving process, the area formed the sheet with the two fixed sheets will change accordingly, as a result,which will produce a change of the electrical capacitance. The size of the swing angle of the moving sheet and its area in the fixed ones as well as the capacitance ratio showed a linear relationship. With alternating current bridge method the electric capacity changes of the sensor,which is corresponding to the voltage output can be measure and then the swinging displacement angle can be calculated out. Experimental validation of the feasibility of the design is made.
