Non-contact short-range radar sensors can detect object movement based on the amplitude and phase readouts. Such systems are widely used in industries, but the medical sector is of special interest. In this work, a Doppler radar system based on six-port interferometric topology is presented to investigate the effect of the reflection by the environment or static part of an object on the received signals from the desired modulator (i.e., a patient's chest). The experimental results show that the static reflector partially distorts the reflected signal of the modulator. In addition, the larger the area, the more significant the distortion is, laying a foundation for future research.