Multilayer SIW Rotman lens antenna in 24 GHz band

We introduce here a multilayer Rotman lens antenna in Substrate Integrated Waveguide (SIW) technology. The lens is realized with two stacked substrate layers, coupled thanks to a new broadband transition quite insensitive to the incident angle of the incoming wave. The lens is connected to an array of slotted waveguides, centrally fed, in order to enhance the reflection and gain bandwidths. To validate the proposed concepts an antenna prototype has been manufactured in the 24-GHz band using Printed Circuit board (PCB) process. Very good scanning performance over an angular sector of ±33° has been obtained with side lobe levels lower than -10dB over the entire field of view. We also show that the true time delay characteristic of the Rotman lens is preserved even if the lens is realized in two stacked layers.