| Antenna is an important module for receiving and transmitting electromagnetic waves,especially high-gain reconfigurable reflectarray(RAA),which plays an important role in longdistance wireless communication.RRA is a new type of high-gain antenna.Compared with the traditional phased array,it adopts the mode of spatial feeding and integrated active device to adjust the phase,which avoids the complex feeding network design,reduces the loss caused by the feeding network,and reduces the design cost.Compared with the mechanical beam scanning of the reflector paraboloid antenna,electronic beam switching is adopted in the RRA to speed up the beam scanning switching rate.In this context,the defects of narrow band,low aperture efficiency and high profile height of the reconfigurable reflection array are studied in this paper.The main research contents of this paper are as follows:1.The phase of the array is optimized based on genetic algorithm.The target value is calculated by the simplified formula of direction diagram and the Fast Fourier Transform is added to speed up the calculation.The physical experience of symmetry of phase distribution is added to the generation of individual gene sequence,which reduces the length of gene optimization and speeds up the convergence speed of the algorithm.In addition,the algorithm used uniform crossover and hybrid selection of offspring and parents to ensure the diversity and steady propagation of offspring in the genetic process.After optimization of the algorithm,flat top beam and dual beam radiation patterns are realized.2.An 1Bit RRA with broadband element structure and low scanning Angle loss is designed.The switching of the resonant state can be realized by controlling the switching of the PIN diode integrated in the unit,so as to achieve the purpose of 180 °difference in phase modulation.In the frequency band from 9.5GHz to 10.8GHz,the reflection unit can achieve the reflection loss within-1dB and the phase change of 180°±20°.Finally,a 12×12 antenna array was designed.The array operated at 10.1GHz,and the main beam gain tested was 18.8 dBi,and the corresponding aperture efficiency was 20.34%.The RRA achieves a beam scanning effect of ±50° and a scanning loss of less than 1.5dB in the Angle range.3.According to the characteristics of high profile and large volume of RRA,an 1Bit folded RRA is designed.According to the principle of reflection law,polarization selective surface can be added above the array surface to reduce the feeding height of the antenna to half of the original one.In order to ensure that the reflected electromagnetic wave can penetrate the polarization selective surface,the unit should have the polarization rotation function of electromagnetic wave while realizing phase shift.The unit can achieve a reflection loss within-2dB and a phase difference of 180 degrees in the frequency band from 9.2GHz to 16.1GHz,corresponding to a relative bandwidth of 54.5%.The beam scanning of ±50° is realized by simulation.The gain of the main beam is 21.3dBi,and the corresponding aperture efficiency is 33%. |
