Research And Implementation Of The Antenna Array Beam-forming

In today's information age,radio technology is often found in military defense and daily life.With the increased demand,the wireless systems increase more and more requirements towards antennas.With the characteristics of high gain,low sidelobe,specific beam and phased beam scanning,the array antenna is increasingly used in radio communications and radar systems.This paper is derived from the requirement of cosecant square beam shaped array antenna in a certain project.A vertical linearly polarized antenna is designed which provides a gain greater than 16.5d Bi.A cosecant shaped-beam antenna is an array of beam-forming elements,which is shaped from 0 to 30.The sidelobe level of square cosecant pattern is about less than-18 d B.Considering the demand of operation,this paper utilizes a general shaping algorithm to design the feed network and complete the broadband antenna design by adopting linear array arrangement.Firstly,the method of the antenna array beam-forming is studied in this paper.The initial amplitude and phase values which are obtained by Fourier inversion method to satisfy the assignment requirement is excited by antenna elements.Then Particle Swarm Optimization(PSO)algorithm are selected to further act on the original value of amplitude and phase.In this paper,the method is verified by an array antenna which is shaped by two side cosecant square beam in pitch direction.The results indicate that the gain of the optimized array pattern flat and the shaped effect of the cosecant square beam is close to target curve.The gain and side-lobe level at the frequency band are better than the technical requirements.This method is universal and suitable for pattern shaping of one-dimensional and two-dimensional arrays.It can make the pattern closer to the target pattern,and the pattern gain fluctuation is lower in the beam shaping range.This scheme has been applied to practical engineering projects at present.A miniaturized low loss 1 min 32 unequal amplitude and phase feed network layout is designed based on multi-layer PCB by using the method of orthogonal hybrid and Wilkinson Unequal Power Division Theory.The loss of feed network is less than 2 d B,the phase error is basically less than 10°,the amplitude error is mostly less than 5%,and the voltage standing wave ratio(VSWR)is less than 1.6.The measured amplitude and phase weights of each port of feed network are substituted into the HFSS model,and the real data is approximately close to model curve.Finally,the physical prototype has been processed by simulation design,and various indicators have been tested.The test data indicate that the pattern curve is approximately close to the target curve at the frequency band,the gain is better than 17 d Bi,the side-lobe level is lower than-20 d B,the VSWR is lower than 2,and other items also fit into the requirements of the indicators.The physical prototype meets the project application.