| With the rapid development of wireless communication technology,through the accurate regulation of the excitation amplitude and phase of each element of the phased array antenna,the active phased array antenna has many functions,such as fast beam scanning,beam synthesis,anti-interference and so on.However,the increasingly complex application environment requires the phased array antenna in the wireless communication system to further meet the needs of miniaturization,broadband and multi-function.Because of its abnormal and diversified electromagnetic scattering characteristics,electromagnetic metasurface structure is widely used in the engineering practice of phased array antennas,which add low scattering,polarization rotation,beam regulation and other characteristics to the traditional phased array and make the antenna to achieve more functions in a limited aperture.In view of the fact that the tightly coupled dipole array antenna has the characteristics of compact structure,low profile and ultra-wideband,this thesis chooses the tightly coupled dipole array as the basic antenna form to study the fusion design scheme of electromagnetic metasurface structure and array antenna.The main work of this thesis is as follows:Firstly,the background and significance of the research work are introduced,and the application and development status of electromagnetic metasurface in antenna design are summarized.Besides,the electromagnetic metasurface theory and the ultra-wideband principle of tightly coupled array antenna involved in the research are described,and the common analysis method of periodic element radiation and scattering characteristics is introduced.Secondly,a tightly coupled phased array antenna with low scattering working in5～18 GHz is proposed.According to the tightly coupled antenna theory,the basic form of the array element is designed,and its radiation characteristics are optimized.In addition,the artificial magnetic conductor structure is incorporated into the design of the antenna element,so that the reflection phase difference between the subarray 1 formed by the fused element and the subarray 2 formed by the original antenna element in the crosspolarization direction is close to 180°.The low-scattering phased array antenna can scatter the energy of vertically incident cross polarized electromagnetic waves to other directions in space and reduce the monostatic radar cross section(RCS).The optimized antenna achieves 3.6:1 bandwidth with the active VSWR is less than 3 when scanning ±60° in E/H plane.Compared with the reference antenna composed of subarray 1,the low scattering phased array antenna achieves more than 7 d B reduction of monostatic RCS at broadside within working band.Finally,a shared-aperture tightly coupled array antenna based on frequency selective structure fusion is proposed.Low-band subarray and high-band subarray work in 0.6～2.4GHz and 3.5～12 GHz respectively,and the two arrays are arranged in the same ground plane.By inserting a meandering semi-lumped inductor into the low-band dipole arm,the low-band dipole array is constructed into a special grid frequency-selective structure,so that it can pass through the electromagnetic waves in the high-band.An infinite periodic array is simulated and optimized under the condition of shared-aperture structure,and a prototype antenna with a 12×12 high-band subarray and an 8×8 low-band subarray is obtained.The simulation and experimental results show that the shared-aperture antenna provides superior performance of dual-band(0.6～2.4 GHz and 3.5～12 GHz)with the VSWR less than 2 for broadside radiation.Meanwhile the VSWR is less than 3 when scanning ±30° in E/H plane in low-band and scanning ±15° in E plane and ±30° in H plane in high-band.The lowest radiation efficiency is more than 80%,while the average radiation efficiency is 88% in high-band and 92% in low-band. |
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