Iris-based 2-bit waveguide phase shifters and transmit-array for automotive radar applications

Three-pole iris-based bandpass filters are proposed as waveguide phase shifters for automotive applications at 77 GHz. Compared to standard configurations with symmetrical irises, asymmetrical designs have been preferred here in order to minimize technological constraints in the perspective of designing beam steering transmit-array antennas. Here the irises are printed on thin Silicon substrates integrated into a WR-12 metallic waveguide. A 210-element transmit-array antenna is also designed at 77GHz using, as building blocks, four different kinds of phase shifters providing a nearly 2-bit phase quantization in the radiation aperture. The phase shifter design are validated in X-band, and a very good agreement between simulations and measurements has been obtained both in amplitude and phase.