Multibeam Rotman lens-fed patch antenna array using SISL technology for 24GHz automotive radar

Abstract

This paper presents a multibeam patch antenna array fed by Rotman lens based on substrate integrated suspended line (SISL) platform. With the advantages of low cost, self-packaging, and wide angle scanning, the proposed antenna can be applied for 24GHz automotive anti-collision radar system. The SISL Rotman lens with sixteen input ports is employed as the beam-forming network (BFN) to generate a corresponding number of beams. With the SISL’s advantages of low loss, even if all substrates use only very cheap FR4 to reduce cost, good lens performances can still be maintained at 24GHz. By utilizing double metal layers with metalized via hole connecting and cutting the undesired substrate, the loss of lens can be further reduced. Moreover, the design of Rotman lens involves tradeoff considerations for wide angle scanning. The radiating part consists of sixteen patch antennas, which are designed using SISL technology for broadband operation and high gain. The experimental results demonstrating a scanning range of ±44° at 24GHz, illustrate that the multibeam antenna array has been successfully demonstrated.