Study Of Phased Array Antenna Based On Substrate Integrated Waveguide For UAV Applications

Phased array antennas(PAAs)exhibit many advantages such as high gain,rapid beam scanning and shaped beam forming,etc.PAAs has been widely used in both military and civilian fields.In recent years,there has been an explosive demand for PAAs in unmanned aerial vehicles(UAV).As an important component of UAV radar,the UAV-based PAA plays a key role in radar performance.Due to the limited space and load capacity of UAV,the PAAs should have the characteristics of wide band,multi-function,wide-angle scanning,and high efficiency,as well as small size,low cost,light weight and high integration.Substrate Integrated Waveguide(SIW)is advantageous in reducing mutual coupling and suppressing surface waves,while microstrip patch antenna(MPA)has been well known for its low profile and easy integration.In this dissertation,SIW and MPA have been introduced as key technologies for UAV-based PAAs.A series of novel PAA with high performance for UAV applications has been proposed.The main contributions of this dissertation are summarized as follows:1.A wideband SIW cavity patch antenna element and its array are proposed.The proposed linearly polarized(LP)stacked patches antenna element is implemented with physically connected technology,to effectively reduce the high profile and ease the complex manufacturing process of traditional wideband stacked patches.Consequently,it offers the advantages of low profile,low cost,and integrated processing.The wideband and wide-angle scanning PAAs demonstrate the features of high efficiency and low gain fluctuations over the working band,therefore have a broad applications prospect.2.A wideband SIW cavity stacked patches antenna element with air cavity and its array are proposed.Patches in traditional stacked patches might be damaged by backdrilling when design as high-integrated tiled PAAs.The proposed circularly polarized(CP)antenna element based on stacked patches technology with air cavity theory in dielectric can be manufactured by two PCBs and one adhesive method,with low cost and free of damaging patches.The proposed wideband and wide-angle scanning PAA is a good candidate for satellite communication systems.3.A simple method is proposed to suppress the blind spots in SIW PAA.Due to surface waves,blind spots may appear in wide-angle scanning in the conventional SIW PAAs,especially at high frequency.Although blind spots are not within the scanning range,it will have a great impact on the scanning performance of the PAA when scanning at ±45°.After in-depth analysis of the mechanism behind blind spots,a simple while effective approach to suppress blind spots has been proposed.Based on the principle of effective antenna aperture,the position of vias of the SIW is adjusted.There is no need to change the structure,the unit size,or the profile.A wider beamwidth active element pattern(AEP)can be obtained.The proposed PAAs can scan up to ±45° in two-dimension(2D)plane with a gain fluctuation of less than 3 d B.The PAA performance is therefore significantly improved.4.Based on the phase controllable characteristics of PAAs,an improved circularly polarized reconfigurable PAA is proposed.Compared with conventional CP reconfigurable PAA,the performance of the proposed PAA is significantly improved.The axial ratio(AR)performance of conventional CP reconfigurable PAAs using pure linearly polarized antenna unit deteriorates seriously when scanning at large angles.A45° LP element is proposed as an improved unit for reconfigurable PAA.Without changing the structure of the array,a high-performance CP reconfigurable PAA is achieved.The PAA can scan up to ±60° in 2D plane with significantly improved the boresight gain of the array,as well as sidelobe level and ARs.5.Based on the phase controllable characteristics of PAAs,using an ingenious arrangement,a LP reconfigurable PAA using CP antenna elements is proposed.The left and right CP antenna elements are placed in a diagonal with rotation angle,and through proper phase compensation,the LP reconfigurable characteristics are achieved.Compared to conventional LP reconfigurable PAAs,the proposed PAAs have a wider working band,owing to CP units' performance.In addition,the proposed PAAs has the advantages of no additional devices,no parasitic effects,low cost.