Comparison of multi-beam pillbox antennas using leaky-wave and slotted waveguide radiating parts for automotive radars at millimeter-waves

This work deals with a comparison between multi-beam leaky-wave and slotted waveguide pillbox antennas. The antenna systems present the same pillbox architecture: feeding part, quasi-optical system and radiating part. Two different radiating parts are considered: a leaky-wave solution and an array of slotted waveguides. In particular, an array of slots etched on the uppermost metal layer of the pillbox structure and 23 waveguides with 8 radiating slots are adopted for the leaky-wave and slotted waveguide solution, respectively. The quasi-optical system and feeding part used in both antennas are the same. The quasi-optical system is made by a pin-made integrated parabola and several coupling slots, and is used to shape and focus the energy coming from the input part to the radiating part. Seven pin-made integrated horns are placed in the focal plane of the integrated parabola to radiate seven beams in the far field. The antenna performances in terms of efficiency, bandwidth and scanning capabilities are compared. Both the proposed antennas are low-cost, low profile, compact, efficient and very promising solutions for applications in the millimeter-wave range, especially for long range automotive radars.