A series-fed low sidelobe antenna for 24-GHz automotive radar

In this paper, a series-fed microstrip antenna array with low sidelobe is presented for 24-GHz automotive radar. Chebyshev distribution is realized by different widths of a quarter-guided wavelength (lambda(g)/4) feedline between adjacent antenna elements, achieving a low sidelobe level (SLL). A 1 x 8 antenna array is designed with the SLL of -23.1 dB at 24.125 GHz, which is extended to 2 x 8 and 8 x 8 planar arrays to improve array gain. The measured gain of 2 x 8 and 8 x 8 planar arrays is 17.3 dBi with an SLL of -23.6 dB and 22.1 dBi with an SLL of -24.7 dB at 24.125 GHz, respectively. In summary, the two antennas have excellent performance in the 24 GHz ISM band with the characteristics of good performance, simple structure, and easy integration, which can be applied to 24-GHz automotive radar.