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Spline-Shaped Microstrip Edge-Fed Antenna for 77 GHz Automotive Radar Systems

Marco Salucci, Lorenzo Poli, Paolo Rocca, Claudio Massagrande, Pietro Rosatti, Mohammad Abdul Hannan, Mirko Facchinelli, Andrea Massa

TL;DR

This work addresses the need for compact, single-layer mm-wave radiators for 77 GHz automotive radars with precise beam control. It introduces a spline-shaped edge-fed microstrip antenna (SS-EFA) whose contour is modeled with Bézier splines to enable a low-descriptor, flexible design space, optimized under the System-by-Design (SbD) framework. A PSO-OK/CSbD-based optimization with a fast digital twin delivers an optimum layout that satisfies impedance, SLL, HPBW, BDD, and PR across 76–78 GHz while accounting for mutual coupling in a linear array; the central element and its replicas achieve good isolation and stable beam steering. Numerical full-wave simulations and PCB-based experimental validation show close agreement and confirm target performance, including $|S_{11}(f)|$ around $-11$ to $-12$ dB, $SLL$ around $-15$ dB, HPBW around $17$ deg, and high polarization purity, demonstrating a practical, single-layer solution for automotive radar applications.

Abstract

An innovative millimeter-wave (mm-wave) microstrip edge-fed antenna (EFA) for 77 GHz automotive radars is proposed. The radiator contour is modeled with a sinusoidal spline-shaped (SS) profile characterized by a reduced number of geometrical descriptors, but still able to guarantee a high flexibility in the modeling for fulfilling challenging user-defined requirements. The SS-EFA descriptors are effectively and efficiently optimized with a customized implementation of the System-by-Design (SbD) paradigm. The synthesized EFA layout, integrated within a linear arrangement of identical replicas to account for the integration into the real radar system, exhibits suitable impedance matching, isolation, polarization purity, and stability of the beam shaping/pointing within the target band [76:78][GHz]. The experimental assessment, carried out with a Compact Antenna Test Range (CATR) system on a printed circuit board (PCB)-manufactured prototype, assess the reliability of the outcomes from the full-wave (FW) simulations as well as the suitability of the synthesized SS-EFA for automotive radars.

Spline-Shaped Microstrip Edge-Fed Antenna for 77 GHz Automotive Radar Systems

TL;DR

This work addresses the need for compact, single-layer mm-wave radiators for 77 GHz automotive radars with precise beam control. It introduces a spline-shaped edge-fed microstrip antenna (SS-EFA) whose contour is modeled with Bézier splines to enable a low-descriptor, flexible design space, optimized under the System-by-Design (SbD) framework. A PSO-OK/CSbD-based optimization with a fast digital twin delivers an optimum layout that satisfies impedance, SLL, HPBW, BDD, and PR across 76–78 GHz while accounting for mutual coupling in a linear array; the central element and its replicas achieve good isolation and stable beam steering. Numerical full-wave simulations and PCB-based experimental validation show close agreement and confirm target performance, including around to dB, around dB, HPBW around deg, and high polarization purity, demonstrating a practical, single-layer solution for automotive radar applications.

Abstract

An innovative millimeter-wave (mm-wave) microstrip edge-fed antenna (EFA) for 77 GHz automotive radars is proposed. The radiator contour is modeled with a sinusoidal spline-shaped (SS) profile characterized by a reduced number of geometrical descriptors, but still able to guarantee a high flexibility in the modeling for fulfilling challenging user-defined requirements. The SS-EFA descriptors are effectively and efficiently optimized with a customized implementation of the System-by-Design (SbD) paradigm. The synthesized EFA layout, integrated within a linear arrangement of identical replicas to account for the integration into the real radar system, exhibits suitable impedance matching, isolation, polarization purity, and stability of the beam shaping/pointing within the target band [76:78][GHz]. The experimental assessment, carried out with a Compact Antenna Test Range (CATR) system on a printed circuit board (PCB)-manufactured prototype, assess the reliability of the outcomes from the full-wave (FW) simulations as well as the suitability of the synthesized SS-EFA for automotive radars.
Paper Structure (7 sections, 6 equations, 17 figures, 3 tables)

This paper contains 7 sections, 6 equations, 17 figures, 3 tables.

Table of Contents

  1. Introduction
  2. SS-EFA Layout and EM Working Principle
  3. Design Process
  4. Performance Assessment
  5. Numerical Assessment
  6. Experimental Validation
  7. Conclusions

Figures (17)

  • Figure 1: SS-EFADesign - Sketch of the antenna geometry with its geometrical descriptors.
  • Figure 2: SS-EFAWorking Principle - Pictorial representation of the SW excited within the SS-EFA structure.
  • Figure 3: SS-EFAWorking Principle - Sketch of two non-uniform width ($\gamma_{1}\neq\gamma_{2}$) and different length ($\beta_{1}\neq\beta_{2}$) SS-EFAs.
  • Figure 4: SS-EFAWorking Principle - Pictorial representation of the behavior of the surface current density.
  • Figure 5: Numerical Assessment ($N=5$) - Screenshot of the SbD-synthesized optimal SS-EFA radiator layout embedded within a $N=5$ linear array of identical $\frac{\lambda_{0}}{2}$-spaced replicas.
  • ...and 12 more figures