Anotace:
A high gain low sidelobe monopulse microstrip array antenna for Ku-band frequency modulated conti-nuous wave (FMCW) radar application is proposed. The design consists of microstrip array radiation front-end and waveguide coupling slot array feeding network back-end. The microstrip array comprises 16×32 series-fed patches etched on the top side and slotted ground on the bottom side. A series of shunt slots in the broad-wall are loaded on a WR51 standard magic Tee waveguide to form a compact low loss monopulse comparator and hybrid feeding network. The radiation front and feeding network is individually fabricated with standard printed circuit board (PCB) and machining process and then can be integrated by advanced assembling process. Precise alignment of waveguide slots and ground slots is obtained during these procedures to achieve accurate excitation. Measured results are in accordance with simulation results and show about 32.5dBi max gain and -25dB sidelobe level (SLL) of sum pattern in E plane and -27dB null-depth of difference pattern at 17 GHz center frequency.