Research On Shared-aperture Dual-band Microstrip Antenna Array

Dual-band dual-polarized microstrip antennas are widely applied in modern communications, microwave imaging, synthetic aperture radar, electronic confrontation and other fields. The application of them to national economic and military purposes is in urgent demand. they are also a hot topic in the field of antenna research. In this paper, the double-frequency microstrip antenna and array is studied, calculation and optimization methods are analyzed in detail. A variety of novel structures of antennas is given. The results show that the design of antennas is satisfactory. Six main subjects included are:First, microstrip antenna are analyzed using the modified theory of cavities, the formula of admittance, size and radiation pattern of microstrip antenna about rectangle and square structures is given. The results have a reference value for the engineering design of the microstrip antenna.Secondly, the symplectic finite difference time domain method (SFDTD) is studied. The scheme, absorbing boundary and stability are analyzed, the resonant frequency, reflection losses of double-frequency dual-polarized antenna are studied using SFDTD.Third, particle swarm optimization (PSO) algorithm is studied. To improve PSO and to convergence region are discussed. PSO is applied to antenna array parameter optimization and antenna pattern comprehension.Fourth, double-frequency double-polarization antenna is studied. The influence of size and medium on the performance of the antenna is analyzed. We put a parasitic strip on the major unit to improve antenna gain and reduce mutual coupling. And this structure will be used in array antenna to solve the problem of blind angle. We use matching structure to enhance bandwidth of the antenna.Fifth, Based on enhanced transmission character, a novel x-band antenna is designed. The influence of physical parameters on the performance of antenna is studied. The measurements results show that:the antenna gained6dB enhancement, E plane half power beam width reduced126degrees, the front-to-back ratio of the antenna radiation pattern increased to25dB. Sixth,A double-frequency double-polarized S/X band antenna array is designed. The antenna array has a frequency ratio of1:3, the impedance bandwidth is greater than9%, polarization isolation is better than25dB, cross polarization level lower than-27dB, and some parameters were superior to the domestic level.