Investigation Of Substrate Integrated Array Antenna With Low Sidelobe Level

In radar and communication applications,the low sidelobe level(SLL)array antenna can greatly improve the anti-interference ability.Substrate integrated array antenna has the advantages of low profile,low loss,easy to integrate,and so on.These features make it attract great attention.However,there are problems of narrow bandwidth,complicated design,and difficulty in realizing the short low SLL circularly-polarized(CP)array antenna.In this thesis,the substrate integrated array antenna with low SLL is designed,which includes the following aspects:First of all,a method to expand the bandwidth of the slot linear array is proposed.In view of the design contradiction between the gain and bandwidth under a certain aperture,the non-alternating slot placement is proposed.In this case,the number of elements is reduced by half.With the non-alternating slot topology,the bandwidth can be expanded while remaining a high gain.On this basis,the low SLL of the H-plane and the unequal power divider of the E-plane are carried out.Finally,the 16×16 low SLL substrate integrated waveguide(SIW)slot array antenna with non-alternating slot placement is fabricated and measured.Compared with the conventional slot array antenna,the bandwidth enhancement is 2.3 times.In the band,the SLL is less than-19d B.Secondly,a simple method to achieve the two-dimensional low SLL slot array antenna is proposed.By the 0°/180°phase transformation of some elements,the SLL of the array antenna can be reduced.For the SIW slot array,0°/180°radiation phase can be easily achieved in a wideband by placing adjacent slots on the opposite/same side without changing the length and offset of the slots.This feature of the SIW slot array is applied to optimize the SLL in both E-plane and H-plane with the improved greedy algorithm.In this case,only reversing the offset direction of partial slots and a simple equal power divider is required.Finally,the 16×16 low SLL SIW slot array antenna with expanded bandwidth is fabricated and measured.The measured results exhibit the relative bandwidth is 3.7%with a return loss of 10 d B and the SLL is less than-18 d B from 93 to 95 GHz.At last,a method to reduce the SLL of the short CP antenna based on the substrate integrated image guide(SIIG)is proposed.Due to the characteristics of the SIIG transmission line,it is suitable for the short leaky wave antenna.Then A-shaped CP element is designed,which consists of two orthogonal linearly polarized structure with equal amplitude and 90°phase difference.With the field cancellation technology,the A-shaped element can mitigate the open-stopband(OSB)effect and then achieve the boresight radiation.Furthermore,the Taylor distribution is used to achieve the taper amplitude distribution,thereby achieving the low SLL.Finally,a 1×10 low SLL SIIG CP leaky-wave antenna array is fabricated and measured.The antenna length is 3.5?₀.At the center frequency,the efficiency is 92.3%,the sidelobe level is-19.1 d B.