A 24 GHz Microstrip Comb Array Antenna With High Sidelobe Suppression for Radar Sensor

In this letter, a compact microstrip comb array antenna with high sidelobe suppression is presented for a 24 GHz radar sensor. Based on the printed circuit board process, several series-fed microstrip comb lines are designed on the substrate to form linear antenna arrays. Chebyshev distribution is adopted for the nonuniform excitation of each antenna element to achieve a very low sidelobe level (SLL). The excitation amplitude is adjusted by tuning the feedline width between the adjacent elements. Under such circumstances, a slimmer array with a tapering distribution is realized. The proposed linear comb array consists of eight elements and is further extended to 8 × 2 and 8 × 8 planar arrays to meet different requirements. The proposed antenna arrays are verified by the simulation and measurement, which are in good agreement. The measured SLLs are better than -28 dB. The measured gains of 8 × 1, 8 × 2, and 8 × 8 comb arrays at 24.125 GHz are 12.2, 15.0, and 19.8 dBi, respectively. The return losses are better than 10 dB and the broadside gains remain stable within the regulated industrial scientific medical band from 24 to 24.25 GHz.