| CPC G01S 7/032 (2013.01) [G01S 7/028 (2021.05); G01S 7/06 (2013.01); H01Q 1/24 (2013.01); H01Q 1/38 (2013.01); H01Q 15/08 (2013.01); G01S 13/88 (2013.01)] | 14 Claims | 

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               1. A radar device comprising: 
            a printed circuit board, PCB, comprising a ground plane, 
                a radar sensor chip package mounted on the PCB and comprising a mmWave radio frequency, RF, integrated circuit and a planar antenna structure configured as an antenna-in-package and oriented in a plane parallel to the ground plane, wherein the mmWave RF integrated circuit is configured to output a mmWave signal to be transmitted by the planar antenna structure, and 
                a cavity, wherein the radar sensor chip package is arranged in the cavity, the cavity having an open side, and the cavity being defined by a conductive rear wall surface opposite the open side, a pair of mutually opposite and conductive sidewall surfaces, a conductive top surface, and a conductive bottom surface, wherein at least a portion of the conductive bottom surface is formed by at least a portion of the ground plane of the PCB, and wherein the sidewall surfaces, the top surface, and the bottom surfaces each extends from the rear wall surface towards the open side of the cavity, 
                wherein a width dimension (W) and a height dimension (H) of the cavity are such that a mm Wave signal output by the mm Wave RF integrated circuit and transmitted by the planar antenna structure excites at least one resonant mode of the cavity. 
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