I. Introduction
There is a strong interest in contact-less vital sign monitoring methods for less static operation and higher flexibility. The use of microwave technology can provide advantages over e.g. image-based systems as it can track certain features without feeling intrusive to the people being monitored. Radar systems may be operated in a wide range of application scenarios and can provide robust and highly accurate measurements. Recent industrial development enabled radar devices to be significantly scaled down. So far, radar development usually required time-consuming simulation, design and tuning of radio frequency (RF) circuits and components. By integrating the complete radar functionality together with its RF circuitry on a single chip, printed circuit board (PCB) size can be reduced while speeding up the overall development process by minimizing RF considerations. Moreover, 3D-printed quasi-optics can be included on the PCB or in the housing to refract and diffract emitted and received radio waves and to further adjust the effective radar coverage to optimally fit the given scenario. In this paper, a miniature yet affordable vital sign radar is presented. The developed radar device operates in the 60GHz industrial, scientific and medical (ISM) band and utilizes a 7GHz bandwidth ranging from 57 to 64GHz.