Research On Broadband Sub Wavelength Phased Array Antenna Technology

With the development of science and technology,the electromagnetic environment is becoming more and more complex.The simple directional radiation antenna has a single function,which is difficult to meet the diverse requirements of modern communication.The antenna with dynamically adjustable electromagnetic beam direction has attracted extensive attention.Mechanical scanning antenna has many problems,such as large space,slow scanning speed,heavy quality and so on.The traditional feed network of phased array antenna is complex,and the cost is relatively high due to the use of T/R module.In recent years,metamaterial has attracted much attention.metamaterial has good regulation performance for the phase of electromagnetic wave.The combination of metamaterial and feed antenna can realize the dynamic regulation of electromagnetic beam.In thesis,the scanning function of sub-wavelength structured phase modulation materials on beams is studied,focusing on how to make dual-frequency and multi-wavelength electromagnetic waves get the same beam deflection effect under the same conditions.The main contents of this paper are as follows:1.Metamaterial unit structure based on geometric phase is designed to realize polarization conversion of circularly polarized electromagnetic waves at 10 GHz and 20 GHz at the same time.Adding metal rings can increase resonance and improve polarization conversion efficiency,and the phases of the two frequency points can be independently regulated and controlled without mutual interference.Using this structure to form a gradient phase super surface,the principle of electromagnetic beam regulation by near-field element guidance technology is further studied under the condition of consistent gradient phase.Combined with near-field element guidance technology,the passive super surface can realize the synchronous dynamic regulation of dual-frequency electromagnetic beam deflection angle,and the maximum beam deflection of 48 can be achieved on the pitch plane with a bandwidth of about 0.6 GHz.2.Combining PIN diode and varactor diode,the metamaterial unit structure based on circuit phase is designed,and the corresponding exploration is made to reduce the coupling between reflective active super-surface units.Finally,the side lobe influence caused by the coupling between units is reduced to a certain extent by using the super-unit form.On the basis of the generalized Snell's law,the phase distribution required by the broadband achromatic beam deflection is analyzed.Combining with the particle swarm optimization algorithm,appropriate structural parameters are selected from the database obtained by parameter scanning,and the dynamic beam deflection of9?11 GHz electromagnetic wave beam is achieved by 10°,20° and 30°,and the influence of chromatic aberration on beam deflection angle is reduced.