Lens Antenna

Vivaldi antenna
© Fraunhofer IAF
Side view of the Vivaldi antenna with dielectric lens.

The separation of the transmitted and received signal is performed on the radar chip, hence only one antenna is necessary. The antenna is realized as an antipodal Vivaldi antenna on the RF-PCB. Due to the 50 µm thin substrate, the antipodal layout won't have a significant rotation in the plane of polarization. Furthermore, compared to a podal Vivaldi layout, a slot line transition is not required. For beam forming and to adjust the opening angle of the radar beam to the application requirements, a dielectric lens is used. The lens is made out of high-density polyethylene (HDPE).The material parameters (attenuation, dispersion) of HDPE are propriate for use in millimeter-wave applications. To save at least one reflecting and lossy air to HDPE interface of the millimeter-wave, the backside of the lens has a conical design. The RF-PCB is inserted into a slot at the tip of the cone, whereby the antenna is enclosed of HDPE for direct transmission into the lens material.