Waveguide Slot Antenna Analysis And Research

Waveguide slot antenna has the advantages of compact structure, high efficiency, convenient installation and power capacity. At the same time, because of the distribution on the aperture of the waveguide slot antenna can be controlled freely, it can realize the narrow beam, shaped-pattern, low side lobe and ultra-low side lobe easily. So it is widely used in Airborne Fire-Control Radar, seeker and so on. This paper researches on the waveguide longitudinal slot antenna array. The main contribution and innovative points can be summarized as follows:Firstly, the basic principle and parameters of waveguide slot antenna are introduced. The way of the equivalent circuits to analyze the waveguide slot is presented.Secondly, Method of Moments is used to analyze the slot which is located on the broad wall of the waveguide. The thickness is considered. The aperture distribution, scattering parameter and the admittance property of the waveguide slot are discussed in detail by computing the equivalent magnetic current. The normalized resonant conductance and resonant length of the slot are increased with the incremental slot displacement off centerline.Thirdly, Genetic Algorithm is used to design the resonance waveguide slot antenna array on the basic of the way of equivalent circuits to analyze the waveguide slot. The current is considered as the objective function, and a novel fitness function is proposed. The optimization design of the 8-slots array, 16-rectangular aperture and 76-circular aperture waveguide slot antenna array is realized to achieve to the low sidelobe by the Genetic Algorithm. It reduces the unknown quantity and the computational time.Then, the method of design for the squint-beam waveguide slot antenna is analyzed. The influence by the cylinder and round platform carrier on the performance of the squint-beam waveguide slot antenna is discussed. The carrier has no infection with main beam, but can improve the side lobe. A squint-beam waveguide slot antenna whose pattern looks like a choanoid with cylinder carrier is designed.At last, the error of designing the waveguide slot antenna array is analyzed. The error of the length, the slot offset off waveguide centerline and the location of the slots, the cladding material is discussed. The error can worsen the characteristic of the side lobe and VSWR.