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Slotted waveguide antenna design for maritime radar system

Waveguide structures have got popularity because of its extensive application in radar system of naval ships and aircrafts. Waveguide models provide high probability of small target detection and reduce rate of false target detection. There are a large number of studies on the waveguide slotted in the wide wall. Researches concerning the narrow wall of the waveguide are much less known. An edge slotted waveguide antenna array based on semicircular end of inclined slots radiating waveguide is proposed. Length of the inclined slot is extended to the adjacent broad wall with semicircular cutting. This extended length increases the resonant length and hence higher gain is obtained. Semicircular cutting at the end of the slot reduces cross-polarization component hence side lobe level obtained are low. Narrow wall inclined slotted waveguide is analyzed and designed to operate in X-band. The radiating slots are etched and rotated alternatively on the broadened top plate with semicircular cutting into the adjacent walls. This technique deletes the radial component of the propagating wave and adds the axial component of the propagating wave. Semicircular cutting increases the resonant length and enhances the gain of the antenna. Designed waveguide structure provides high gain, and cross-polarization component is minimized. Gain of 26 dB is obtained from the simulation results obtained in HFSS (High frequency Software Simulation) and side lobe level obtained is around 20 dB while hardware design provides the gain of 24.5 dB measured on VNA (Vector Network Analyzer) keeping the side lobe level minimum. The designed simulated structure is fabricated in the workshop and tested in the laboratory for the evaluation of the simulation results. The designed slotted waveguide is tested for the gain and cross-polarization component by using a VNA.