DESIGN AND OPERATION OF AN EDGE-WALL SLOTTED WAVEGUIDE ARRAY ANTENNA WITH ULTRALOW SIDE LOBES FOR APPLICATION OF OFF-SHORE RADAR

This paper presents the design, fabrication, and operation of an edge-wall slotted waveguide array antenna with metal flare for the generation of ultralow side lobes fan-beam radiation. The single traveling wave array antenna consists of 71 radiating elements. The radiation pattern at the operating band was designed utilizing the Taylor's aperture distribution to achieve an ultralow side lobe level (SLL) of-33 dB. The mathematical relationship between the slot characteristics and the conductance is evaluated by the least squared quadratic curve fitting procedure. Finite element method software is used to analyze the various antenna characteristics of the radiating slots, including return loss, insertion loss, and radiation patterns. The array antenna was fabricated and the performance characteristics of the antenna were measured in an antenna near-field measurement chamber. The well match of the measured and simulated results indicated the excellent design of the array antenna with ultralow side lobes. Finally, the unit was fitted onto a search radar system and an experimental test on the radar returns on Keelung Islet was carried out. The clear radar signals of the islet showed the well design of the unit.