Fabrication and measurement of an antenna radiating polarization parallel to a substrate in a direction perpendicular to a side surface of the substrate for millimeter-wave radar board

This paper describes a reflector-backed dipole antenna embedded in a substrate for 79 GHz band radar application. The antenna radiates in a direction perpendicular to a side surface of the substrate with polarization parallel to a substrate main surface. From a viewpoint of manufacturing cost, radar boards are often composites of low-loss substrates for high-frequency bands and general-purpose substrates such as flame-retardant type 4 (FR-4). The asymmetric structure of the composite substrate in the thickness direction deteriorates the radiation pattern in the plane parallel to the thickness direction. By removing the FR-4 substrate below the antenna, the degradation of the radiation pattern is mitigated. In this paper, the design and the measured results of the proposed antenna are demonstrated.