Generally, a laser Doppler velocimetry can estimate particle velocity by forming a standing wave region with crossed beams and by counting the brinks of particle scattering. If we apply this concept to microwave measurement in near field, an arrayable measurement of object parameters will be expected with low cost. This paper presents a novel velocity and volume estimation method of small object based on reflection coefficient measurement using near field sensor with an interdigital ring coupler structure. The sensor is designed with electrostatic analysis and FDTD analysis. Experiments are carried out with a constructed sensor. Experiments and simulation results agree well. It implies that this sensor has possibility to measure not only the velocity but also the volume of the target.