A Compact, Versatile Six-Port Radar Module for Industrial and Medical Applications

The Six-port receiver has been intensively investigated in the last decade to be implemented as an alternative radar architecture. Plenty of current scientific publications demonstrate the effectiveness and versatility of the Six-port radar for special industrial, automotive, and medical applications, ranging from accurate contactless vibration analysis, through automotive radar calibration, to remote breath and heartbeat monitoring. Its highlights, such as excellent phase discrimination, trivial signal processing, low circuit complexity, and cost, have lately drawn the attention of companies working with radar technology. A joint project involving the University of Erlangen-Nuremberg and InnoSenT GmbH (Innovative Sensor Technology) led to the development of a highly accurate, compact, and versatile Six-port radar module aiming at a reliable high-integration of all subcomponents such as antenna, Six-port front-end, baseband circuitry, and digital signal processing in one single package. Innovative aspects in the RF front-end design as well as in the integration strategy are hereby presented, together with a system overview and measurement results. 1. Introduction Optical high-resolution, contactless distance measurement techniques such as laser interferometry and laser pulse time-difference measurements have been widely implemented for industrial and medical applications. The drawback of optical techniques is the difficulty to penetrate dust and fog with the laser in harsh environments as optical lenses and mirrors can get dirty. Furthermore, with increasing suspended particle density in the propagation environment dampening and scattering effects increase so that the laser cannot reach the surface of the object under investigation. These inconveniences of laser based systems are the cause of an increasing interest in alternative nonoptical measurement techniques that are robust against such industrial environment conditions. One of the main noncontact-based alternatives to laser is radar. Radar-based measurement techniques work also when a direct optical line of sight to the object under investigation is not guaranteed since radar waves can propagate much better through foggy or dusty air. Furthermore, even bulky and optically nontransparent dielectric slabs or nonmetallic shields can be penetrated by the radar signal [1, 2]. Within the last decade, radar technology has been rapidly expanding in industrial, automotive, and medical application areas [3]. Advanced positioning and sensor feedback tasks in automation processes rely on high precision