Research And Design Of Tightly Coupled Wideband Array Antenna Based On Different Processing Technologies

Compared with the traditional array antenna technology,the tightly coupled array antenna avoids the coupling effect and is easy to realize the characteristics of Ultra Wide Band,high gain,low profile and conformalization,which gradually becomes a research focus in the modern wireless communication,satellite navigation,radar and other wireless communication systems.The existing tightly coupled array antennas are mostly manufactured by PCB process,and the working bandwidth can cover multiple octaves.But the structure of the tightly coupled antenna array is complex,and at higher frequencies,the antenna performance is easily affected by the circuit material parameters and the accuracy of PCB process.In this paper,based on the design idea of tightly coupled array,3D printing technology and rectangular micro-coaxial process are introduced to extend the design of tightly coupled antenna array to millimeter wave frequency band,and the analysis,design and testing of tightly coupled broadband antenna array are carried out.The main work of this thesis is as follows.(1)By deeply analyzing the principle of tightly coupled antenna broadband operation,the role of each part in the tightly coupled antenna array technology and the influence on the overall radiation performance are explored.What’s more,based on the principle of the tightly coupled antenna,an ultra-broadband tightly coupled array antenna dual-polarization unit with an operating bandwidth of 2-18.6 GHz(VSWR ≤ 2.5)is designed.The array element consists of two cross-placed dipoles,which is fed by a broadband printed Marchand Balun,and a rectangular patch is inserted into the slot between the two adjacent arms to increase the coupling capacitance of the dipole end so as to achieve a wider impedance bandwidth.At the same time,a toroidal resistive type frequency selective surface suppression radiation zero is used to further expand the impedance bandwidth.After optimization,the tightly coupled antenna array element achieves an ultra-wide operating bandwidth of 2-18.6 GHz under the periodic boundary conditions,while its profile height is only 1/10 wavelengths at the low frequency of the operating band,which has a smaller profile height and good broadband performance compared with the conventional broadband antenna array.(2)The feasibility of realizing the simple machining mode of the broadband antenna is explored,and a coaxial Marchand Balun fed wideband dipole antenna was designed and fabricated by combining 3D printing technology.The surface is metallized once formed using 3D printing technology.The final test results show that the antenna has a working bandwidth of 1.61-3.23 GHz,and the in-band gain is greater than 2 d Bi,which verifies the feasibility of 3D printing technology for making broadband antenna.It also analyzes the effect of electroplating different metals on antenna gain.(3)The existing tightly coupled antenna designs are all based on PCB printing technology,limited by the process accuracy and the poor high-frequency performance of traditional transmission lines,and the designed frequency band is basically below K-band.By combining the tightly coupled antenna element with rectangular micro-coaxial process,the design of the tightly coupled antenna is extended to the millimeter wave band in this thesis,which well combines the advantages of the rectangular micro-coaxial process in high integration and low loss.The tightly coupled antenna unit is designed to meet the requirements of micro-coaxial technology,and the operating frequency band reaches 7.3-38 GHz(VSWR≤2.5),covering multiple bands.