Microstrip-line Type Bruce Array Antenna with Low Sidelobe Level for Millimeter-Wave Radar

In the case of the radar in mmWave, a radar antenna with high gain, simple structure, and low loss is required due to increased transmission and manufacturing losses. Also, the radar needs a low sidelobe level to eliminate clutter and interference. Therefore, this paper proposes the 1 × 8 array microstrip-line type Bruce antenna fabricated on a multiple-layer printed circuit board (PCB) with a low sidelobe level. A series-fed network fed the antenna elements, and a low side lobe level was achieved by applying different thicknesses of radiation lines and designing a feeding network. It has a high measurement gain of 15.7dBi and a low sidelobe level of −27 dB in the ϕ = 0° plane and −22.7 dB in the ϕ = 90° plane. The proposed antenna was applied to a K-band frequency-modulated continuous wave (FMCW) radar system, and the clutter removal experiment was measured.