A Study On Wideband And Wide Angle Scanning Phased Array Antenna

In the past decades,phased arrays have been receiving great attentions,especially those with wide bandwidth and wide-angle scanning ability.This paper presents new design methods and performance improvement of wideband and wide-angle scanning phased array,which consists of the following parts:1.A C-band wideband wide-angle scanning linear phased array is designed and,to achieve wideband property,a wideband electromagnetic band gap(EBG)structure whose bandwidth of reflection phase ranging from-90° to 90° is 59.7%,is employed as the ground plane for dipole antennas.The designed linear array covered with a single-layer wide-angle scan impedance matching(WAIM)layer features an impedance bandwidth of 19.8%,with the ability to scan up to 80° in the H plane,and the gain variation is less than 3dB.In order to validate the simulation results,an array prototype and two feed networks for broadside and 80° scan respectively are fabricated.A good agreement between simulated and measured results is observed,which demonstrates the correctness of the simulation results.2.In this section,we proposed an ultra-wideband wide-angle scanning phased array with an impedance bandwidth over 5:1,and an ability to scan up to 80° and 45° in the E plane and H plane,respectively.Connected long slot array is employed in the proposed design and,similar to the tightly coupled dipole array,the inherent wideband property makes it a perfect candidate for ultra-wideband and wide-angle scanning phased array.In order to compensate the inductance introduced by the ground plane,a meandering slot is added and the strong capacitive coupling can be obtained by carefully adjusting the geometrical parameters,thus an enhanced impedance matching is achieved.On the other hand,the design methodology of frequency selective surface(FSS)WAIM layers based on the equivalent circuit model is presented.The optimal structures of FSS WAIM layers are obtained via a self-written MATLAB program,in which the Particle Swam Optimization algorism(PSO),a robust optimization algorithm is utilized to approach the global minima and speed up the process.The proposed array achieves a 5.54:1 impedance bandwidth(0.87 ~ 4.82 GHz)with active VSWR < 3 for all 0° ~ 80° scans in the E plane,and a 5.12:1 impedance bandwidth(0.82 ~ 4.2 GHz)with active VSWR < 3 for 0° ~ 45° scans in the H plane..A 31×6 array prototype is fabricated and measured,and a good agreement between simulations and measurements is observed.This approach provides a considerable increase in design efficiency,as well as a significantly improved scanning performance across the entire frequency band.