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 24 GHz radar sensor. Based on printed circuit board (PCB) process, several series-fed microstrip comb lines are designed on the substrate to form linear antenna arrays. Chebyshev distribution is adopted for 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 adjacent elements. Under such circumstances, a slimmer array with a tapering distribution is realized. The proposed linear comb array consists of 8 elements, and is further extended to 82 and 88 planar arrays to meet different requirements. The proposed antenna arrays are verified by simulation and measurement, which are in good agreement. The measured SLLs are better than -28 dB. The measured gains of 81, 82 and 88 arrays at 24.125 GHz are 12.2 dBi, 15.0 dBi and 19.8 dBi, respectively. The return losses are better than 10 dB and the broadside gains maintains stable within the regulated Industrial Scientific Medical (ISM) band from 24.00 GHz to 24.25 GHz.