Design and Simulation of Long Slot SIW Leaky Wave Antenna for Automotive Radar Application

This paper presents the design and simulation of a leaky wave antenna utilizing substrate-integrated waveguide (SIW) through various methodologies such as numerical analysis, HFSS, and simplified aperture function. The primary focus of the antenna design is its operation at 77 – 79 GHz, a commonly used frequency band for automotive radars. Initially, the mathematical foundation is discussed, followed by an explanation of two numerical approaches employed to determine the curve function of the slot. Given the lightweight and compact nature of radars operating in this frequency range, a substrate-integrated waveguide (SIW) was chosen as the waveguide type for the antenna design. Two alternative approaches have been employed to depict the slot on the waveguide, deviating from the conventional technique, and their respective performances have been evaluated. The initial approach replaces the slot with a series of holes, which serve as sampled points for a curve function. Conversely, the second approach maintains a rectangular shape for the slot with a narrow width, and instead of curving the slot, the waveguide vias are tapered to conform to the desired curve. The initial antenna configuration has achieved a gain of 4.3 dBi, a side lobe level (SLL) below 30 dB, and a bandwidth spanning 500 MHz Conversely, the subsequent design exhibits a gain of around 4 dBi, a SLL below 27 dB, and a bandwidth spanning 300 MHz.