Array Design Of Ku/Ka Dual-frequency Shared Aperture Phased Array Antenna

AESA(Active Electronically Scanned Array)antennas are widely used in the military industry,especially in the field of missiles,because of their fast scanning,beamforming and ability to perform multiple functions at the same time.Looking at the actual application scenarios of the missile-borne antenna,it is required to have a wide airspace coverage,strong anti-interference ability and multi-functional use,etc.,which promotes its development in the direction of broadband,low sidelobe,and dualfrequency shared aperture.Therefore,from the perspective of engineering application,this paper aims to study the Ku/Ka dual-band shared aperture AESA antenna used in the missile-borne field with broadband and low sidelobes.The work includes the following aspects:(1)Design of Ku/Ka dual-frequency shared aperture Phased Array Antenna Unit.This part designs a Ku antenna unit to achieve horizontal polarization and Ka antenna to achieve vertical polarization respectively,and the Ku and Ka antenna units choose the layout of one with three.which are integrated in the shared aperture of the square with the side length of 0.48?0,The Ku antenna adopts the design idea of laminated patch,and effectively expands the antenna bandwidth through slot coupling and air cavity,and obtains a relative bandwidth of 33.8%.Ka antenna also adopts laminated patch structure to achieve a relative bandwidth of 15%.In order to improve the channel isolation between Ku antenna and Ka antenna in Ku frequency band,Ka antenna adopts the form of a slot-coupled microstrip antenna,and strengthens the shielding through grounding holes.Simulation analysis shows that the antenna with this structure has the characteristics of passing high frequency and blocking low frequency,and the Ku and Ka antenna achieves channel isolation higher than 60 dB in the Ku frequency band.The design of the shared aperture antenna unit has the characteristics of wide frequency band,miniaturization and high isolation,and can be applied to the compact dualfrequency shared aperture phased array antenna.(2)Array design of Ku/Ka dual-frequency shared aperture phased array antenna array.In the shared aperture,the Ku antenna adopts a random array of 208 elements,and the Ka antenna is a regular array.Firstly,Ku antenna uses genetic algorithm to obtain a low sidelobe effect of less than-16 dB at the normal sidelobe level.For Ka antenna,two array forms are selected,one is a regular full array layout,and the highest sidelobe level when the beam scans ±40° in the working frequency band is always lower than-16 dB.Another arrangement is to choose "regular full array + sparse array",that is,the Ka array elements of the face edge are sparse,the sparse rate is 76.9%,and the sidelobe level is always below-18 dB within the canning range of ±40°.Then,the physical processing and test analysis are carried out on the above two array forms.The measured results show that the impedance bandwidth and scanning gain decrease of each channel basically meet the requirements of the index.It can be seen that the design of this scheme is feasible,and lays the foundation for the engineering application of dual-frequency shared aperture phased array antenna.