High-Gain Design of a 6 × 26 Slotted Waveguide Array Antenna with a Grid Cavity for Ku-Band Wave-Monitoring RADAR Systems

This paper proposes a high-gain slotted waveguide array antenna design for Ku-band wave-monitoring radar systems. The antenna structure features a two-layer design that integrates the feeding and radiating sections. A grid cavity is stationed on top of the radiating section to suppress the first sidelobes and increase antenna gain. Subsequently, the antenna combined with the grid cavity is designed and fabricated, and its performance is analyzed. The measurement results show a frequency bandwidth of more than 2.8% based on the −10 dB reflection coefficients. The implementation of the grid cavity improves the first sidelobe level by approximately 2 dB. The measurement results also indicate that the proposed antenna achieves a gain of approximately 30.5 dBi—an improvement of approximately 2 dB over that of a conventional slotted waveguide array antenna without a grid cavity. Based on these results, the proposed antenna can be expected to significantly contribute to the development of Ku-band wave-monitoring radar systems for coastal erosion prevention.