SIW Folded Cassegrain Lens for Millimeter-Wave Multibeam Application

A folded Cassegrain lens in substrate-integrated waveguide (SIW) is presented in this letter. The proposed folded Cassegrain lens is composed of three layers. The input ports and the output ports are allocated in the bottom layer and the top layer, respectively. The stimulated cylindrical wave from the bottom layer is transferred into planar wave and then transmits to the top layer after the reflection and the coupling of the proposed lens. In contrast to the previously reported reflector lens, such topology can efficiently suppress the blockage issue and maintain the inherent symmetry simultaneously. To demonstrate its feasibility, a multibeam array based on the SIW folded Cassegrain lens is designed. Finally, fabrication and measurement are conducted, and satisfactory agreement is exhibited.