Research Of Ultra-wideband Dual-polarization Tightly Coupled Phased Antenna Array

Modern radars and electronic warfare systems often require active and passive composite and common aperture operation.Therefore,the demand for multi-octave antenna systems is becoming more and more urgent.In this thesis,ultra-wideband antennas have received increasing attention.Tightly coupled array antennas belong to the new generation of antennas,which have the advantages of wide frequency band,easy miniaturization,easy common type,easy integration,etc.,and can be widely used in communication,radar and electronic warfare systems.The main research object of this thesis is the ultra-wideband dual-polarization tightly coupled phased array antenna.The main content of the paper includes the following parts:First of all,the thesis analyzes and simulates based on the principles of balun and absorber.Based on the principle of balun balanced feeding and impedance transformation,using coaxial tapered line and microstrip tapered line structures respectively,two ultra-wideband baluns have been designed.Both operating frequency ranges can cover 2-18 GHz,and the VSWR?2,realizing the characteristics of ultra-wideband and low profile.Based on the working principle and equivalent circuit analysis of the broadband absorber,a broadband absorber loaded with lumped resistance has been designed.Its impedance-to-bandwidth ratio is 3.56:1 and the absorption rate is greater than 90% in the operating frequency band 5.09-18.15 GHz,and the wave absorption performance is good.Secondly,a planar dual-polarization tightly coupled array antenna was designed.The characteristics of the array antenna unit structure are as follows: the unit form is an interdigital dipole,which forms a dual-line polarized antenna that is perpendicular to each other;a wave-absorbing layer is loaded between the antenna and the ground plate to change the transmission characteristics of the antenna unit and expandBandwidth;the feed structure is a microstrip tapered balun;a wide-angle matching layer is loaded above the antenna to improve the impedance matching and wide-angle scanning performance of the antenna unit.After simulation and verification,the dual-polarized antenna unit can work in the frequency band of 2-18 GHz,its beam scanning angle on the E-plane and H-plane can reach ±45°,and the isolation degree of co-polarization and cross-polarization is greater than 10 dB.The 8×8dual-polarization tight-coupled array antenna has been processed,assembled and tested.The antenna has good performance and meets the design index,which verifies the correctness of the design scheme.Finally,a vertical dual-polarization tightly coupled phased array antenna is designed.Loading a lightweight periodic structure into the antenna unit structure not only simplifies the array structure,but also enables the phased array antenna to have a wider scanning angle.The introduction of grounding short-circuit line and lumped resistance between the dipole and the metal ground can effectively suppress the in-band resonance.The truncation effect is analyzed and the parasitic element with terminal matched load can suppress the truncation effect at the edge of finite antenna array.The simulation results show that the structure can work at 2-18 GHz,the beam scanning angles on the E and H planes can reach ±60°,and the isolation degree of co-polarization and cross-polarization are above 15 dB.