Research On Miniaturized Array With Slot Antennas Fed By Unconventional Cavity For Low Sidelobe

With the continuous development of communication technology,the 5G era is coming out.With the continuous increase in people's living standards,people have higher requirements for the performance of communication equipements,especially in minimizing low sidelobes of antennas.At the same time,in the war scene,people also hope that the antenna can be durable and easy to conform.The traditional waveguide slot antenna can meet the requirements of the above-mentioned miniaturized low sidelobes and is easy to conform.However,in the low frequency band,the feed is difficulty due to the influence of the long line effect,which brings a big challenge to the design of the feed system.In response to the above problems,it has been proposed to overcome the long line effect of the low frequency band by means of slitting on the cavity instead of slitting on the waveguide.The effect is ideal,but there are also many problems.The coupling fed gap of the conventional cavity slot antenna is in the center of the cavity,which causes the amplitudes of the excitation of the equally spaced radiation slots to be the same,forming a stepped feed,which is not conducive to beamforming the antenna.In this paper,MATLAB is used to simulate the slot feeding of the cavity center.It is found that this design method will lead to the increase of the sidelobes.In this paper,an unconventional slot antenna with unequal cavity and a coupling gap deviating the center of the cavity is proposed.A array with 128 elements comes from 32×4,multiplying 32 array elements by four radiation slots from each element.Looking at the antenna from above,its coupling fed gap being not in the center of the cavity and the different distances from the four radiation slots result in different conductance of the four radiation slots.At the same time,for the problem of phase deviation of the radiation port caused by the coupling gap not being in the center,this paper adjusts the length of metal arm to make the four radiation slots have the same phase.Moreover,since this antenna is designed for imaging and ranging,we designed a differential feeding network with three ports,i.e.a sum port,azimuth difference,and a pitch difference port.The sum and difference feed network are composed of magic T and adapters,and the whole array is a metal structure,which is simple in design and easy to process.The measured results is in agreement with the designed requirements.In this paper,a miniaturized antenna array with unusual cavity is designed for low sidelobe.Realization of low sidelobes depends on its feeding center,where the location of antenna deviates from.At the same time,this paper also designs a set of metal structure of sum and differential feeding network for the antenna.After measurement,we have the 24 dB gain of the antenna in the sum port,with-16 dB the sidelobes,-30 dB the zero depth in the pitch difference port,and-48 dB the zero depth in the azimuth difference port.From the above results,it is believed that the design goal is achieved by our fabricated array.