公开(公告)号：US20220031172A1

公开(公告)日：2022-02-03

申请号：US17299271

申请日：2018-12-24

Applicant: Google LLC

Inventor： Yuchu He ,  Jiang Zhu ,  Changzhan Gu ,  Haijiang Ma

IPC: A61B5/0205 ,  G01S7/02 ,  G01S7/35

Abstract: Techniques and apparatuses are described that implement a smart device-based radar system capable of detecting human vital signs using a compact circularly-polarized antenna. A radar system includes at least one compact circularly-polarized antenna with a patch antenna and a quadrature hybrid coupler. The quadrature hybrid coupler is on a separate plane that is above or below the patch antenna. By vertically stacking the patch antenna with the quadrature hybrid coupler, lateral dimensions of the radar system can be reduced relative to other antenna configurations or designs. The quadrature hybrid coupler can also have a ring-shape design to improve isolation and polarization purity of the compact circularly-polarized antenna relative to a rectangular design. The compact circularly-polarized antenna enables a radar system operating at frequencies between approximately 1 gigahertz (GHz) and 24 GHz to be implemented within a variety of small smart devices.