Design of Frequency Scanning Narrow Wall Slotted Waveguide for Mortar Locating Radar

Tracking the trajectory of a projectile such as a mortar requires a radar system with high angular resolution and fast response time. Frequency scanning antennas are a potential solution because of their ability to change the direction of the beam without mechanical components. This study aims to design and develop a frequency scanning narrow wall slotted waveguide antenna in the S-band. The antenna is designed to be able to direct its beam without requiring a mechanical scanning mechanism or phase shifter. By utilizing the phenomenon of beam steering based on frequency variations, this system aims to produce angular scanning that can be used on a mortar locating radar. The antenna operates at a frequency from 2.7 to 3.1 GHz using the WR-284 waveguide standard. The antenna is operated as a traveling array by adding slots to the narrow wall of the waveguide and matched loads at the end of the waveguide. The antenna design process includes modeling the characteristics of wave propagation in the waveguide, determining the dimensions and positions of the slots to produce the desired radiation pattern, and simulations to evaluate the antenna performance. The simulation results show that the antenna can perform angular scanning up to 13 degrees with a bandwidth of 400 MHz. The antenna has an average gain of 17.35 dBi and a sidelobe level of ™11.6 dB. The antenna efficiency varies between 65% to 90% with a beamwidth variation of 3.76 degrees. This performance shows that the designed antenna meets the requirements for use as a mortar locating radar.