A Study On Low Profile Ultra-Wideband Tightly Coupled Phased Arrays With Low Scattering

The rapid development of wireless electronic technology has put forward higher requirements for phased arrays.On the one hand,phased arrays are required not only to achieve ultra-wideband,and wide scan angle,but also to achieve miniaturization,lightweight,as well as low profile,to conform to the platform.On the other hand,due to the fact that the phased arrays are gradually becoming one of the main sources of the electromagnetic scattering of the platform,phased arrays are also required to meet the needs of low scattering characteristics.Therefore,it is of great significance to study the scattering characteristics of phased arrays.At present,a novel type of wideband phased arrays making use of the tightly mutual coupling between closely spaced elements to broaden the bandwidth is becoming one of the research hotspots in the international antenna community.Compared to the traditional phased arrays,the tightly coupled phased arrays are more suitable for ultra-wideband,wide scan angle,low profile and miniaturization.However,the studies on the scattering characteristics of this new type of phased arrays are rarely seen.This thesis focus on the study of the ultra-wideband phased arrays with 2-D scanning properties based on the enhanced mutual coupling.An in-depth study on their radiation and scattering characteristics is presented,and the array characteristics of low profile and low scattering characteristics are achieved.The main work or innovation of the thesis are as follows.Firstly,the relevant background and significance of studies on tightly coupled phased arrays are introduced.The international and domestic research process and current status of the phased arrays and antenna scattering are reviewed.Secondly,the working principle of phased arrays and the method for achieving traditional ultra-wide band phased arrays are reviewed in detail.The principle for achieving ultra-wide band phased arrays based on the tightly mutual coupling effect is also introduced.Meanwhile,a detailed introduction of the basic theory on scattering cross section(SCS)and antenna scattering is presented.Thirdly,based on 2-D array with tightly coupling,an ultra-wideband phased array element and their respective array operating in P-L band with low profile are designed and simulated.The array can achieve 4:1 bandwidth when scanning up to ±60° in the E-plane for VSWR?2.5 and ±45° in the H-plane for VSWR?3.0.Fourthly,the scattering characteristics of the ultra-wideband tightly coupled phased array are analyzed,in comparison with a Vivaldi ultra-wide band phased array with the similar aperture area and the same bandwidth as the reference antenna.The simulated results show that the scattering performance of the ultra-wideband tightly coupled phased array is better than that of the Vivaldi ultra-wideband phased array.Fifthly,a novel approach of using the polarization conversion metasurface to optimize the scattering performance of the ultra-wideband tightly coupled phased array is proposed.The SCS reduction of the array within a specific band and angle of incidence has been achieved without affecting the profile and radiation of the antenna.Finally,the ultra-wideband tightly coupled phased array is manufactured and measured.Measured results are in good agreement with the simulation results,which Validates the correctness of the design of low profile and low scattering ultra-wideband tightly coupled phased array.