Research On Optimal Design Of Spherical Phased Array Antenna

Since the birth of phased array antenna technology in 1960 s,it has been developing rapidly in recent decades with the obvious advantages of replacing the mechanical rotating antenna scanning mode and tracking the multi-target without inertia.With the development of technology and the emergence of new requirements,the disadvantages of planar phased array antenna become apparent.Scanning range of conformal phased array antenna is 3/4 sphere.The shape of conformal phased array antenna is similar to carrier surface,which meets the requirements of aerodynamics.The other advantages of conformal phased array antenna are low profile,lightweight and high space utilization rate.Conformal phased array antenna has a wide application prospect.The goal of this paper is research of spherical phased array antenna which belongs to conformal phased array antenna.The research and simulation of far field,array forms,polarization phase compensation and sparseness of spherical phased array antenna has been finished,and the design of spherical phased array antenna is carried out,which is prepared for the engineering of spherical phased array antenna.Specific work summary is:1.The basic model and polarization theory of conformal phased array antenna and mutual coupling effect between elements are researched.Then theories and comparison of genetic algorithm and immune algorithm is given.2.Specific characteristics of conformal phased array antenna are researched.The directional diagram of units is different with each other,thus Euler transformation is needed to finish coordinate transformation,which leads to large amount of calculation.This paper puts forward a method which can simplify the calculation of coordinate transformation,and analyzes mutual coupling effect between elements with active element pattern.At last,the mathematical model related to polarization is built.3.Array forms of conformal phased array antenna are researched.This paper gives subdivision process of some typical polyhedrons with subdivision projection method,top-added method and top-truncated method.4.Non-collinear polarization of conformal phased array antenna is researched.This paper gives the array form of spherical array,pole distribution and equator distribution,and derives formula of their directional diagram,and puts forward a phase compensation method based on scanning angle which is changed.The simulation shows that the method can effectively solve the problem of worse directional pattern lead by non-collinear polarization.5.Sparseness of conformal phased array antenna with self-adaptive immune genetic algorithm is researched.Traditional genetic algorithm has disadvantage of prematurity,degeneration and slow convergence.This paper puts forward self-adaptive immune genetic algorithm based on immune algorithm and genetic algorithm.In the self-adaptive immune genetic algorithm there is self-adaptive commute and mutate operator,vaccines operator,immune detection operator and immune balance operator,which improves individual substitution and population diversity,and,meanwhile,increases convergence speed to global optimal solution.Sparseness with self-adaptive immune genetic algorithm can keep the gain after sparseness similar to the one of full arrays within certain scanning angle.6.Sparseness of spherical phased array antenna based on polygon stitching.Spatial weighting is needed in calculation of directional diagram of conformal phased array antenna.If the maximal side-lobe level is low,improvement of side-lobe performance with sparse algorithm is meaningless.Using self-adaptive immune genetic algorithm for sparseness of planar sub-array can keep the gain after sparseness similar to the one of full arrays within certain scanning angle,and planar sub-arrays are used to split into spherical array,which finishes the sparseness of spherical array indirectly.