Research On Switch Antenna Array Technology And Its Application

Phased array radar has received considerable attention due to its significant advantages in fast beam switching.Meanwhile,digital array radar with digital beamforming technology is the future development trend.However,the high cost of phased array radar and digital array radar limits its application area.The use of switched antenna array technology can effectively reduce the number of channels,and further reduce the cost,power consumption and volume of digital array radar hardware.For stationary targets,traditional digital beamforming algorithms and super-resolution algorithms can be directly used to switch antenna array radars to achieve angle estimation.However,for moving targets,switching antenna array radars face angle-velocity coupling problems.If the phase introduced by motion is not compensated,it will cause angle estimation errors and even lead to estimation errors.In order to solve the angle-velocity coupling problem of switching antenna array radar and overcome the shortcomings of existing motion compensation methods,we conduct the following research work:1)The signal models of the switched antenna array radar are established,including switch antenna array(SAA)frequency modulated continuous wave(FMCW)radar and time division multiplexing(TDM)multiple input multiple output(MIMO)FMCW radar.The phase characteristics introduced by motion and its effects of digital beamforming are analyzed,which promote the subsequent study of moving target phase compensation methods.2)A phase elimination method based on double time switching scheme is proposed.The signal is received according to the double-time switching scheme.The motion-induced phase is eliminated by simple signal processing,and the angle-velocity coupling problem is solved.The angle of the moving target is accurately estimated.The method does not need to use an optimization algorithm to solve the optimal timing,nor does it need to estimate the speed,and avoids the estimation problem of the fuzzy speed.3)A phase extraction method based on reference-element is proposed.Firstly,the signal is received according to the reference-element based switching scheme.Then,the motion-induced phase is extracted by processing the phase of the reference-element signal.Finally,the extracted phase is used to construct a phase compensation matrix to compensate the array signal.Compared with the phase elimination method based on double time switching scheme,the time required to receive a round of signals is greatly reduced.4)A phase extraction method based on specific switching scheme is proposed.Firstly,the signal is received according to the specific switching scheme.Then,the motion-induced phase is extracted by processing the phase of the 2nd and 3rd element signal.Finally,the extracted phase is used to construct a phase compensation matrix to compensate the array signal.The time consumed by receiving signals in one round is equal to that of the conventional sequential switching scheme.5)The existing phase compensation methods are difficult to solve the angle-velocity coupling problem of low SNR moving targets.Therefore,we propose an angle estimation method of low SNR moving targets for SAA FMCW radar.Firstly,the signal is received according to the conventional switching scheme.Secondly,the SNR is increased by digital beamforming,and the velocity estimation is performed.After that,the array signal is compensated using the estimated velocity.Finally,the angle estimation is completed by another digital beamforming.This method effectively solves the angle-velocity coupling problem of low SNR moving targets.For TDM MIMO FMCW radar,a crossed switching scheme is proposed,which makes the angle estimation method of low SNR moving target for SAA FMCW radar can be applied to the TDM MIMO FMCW radar.The performance of the angle estimation methods for low SNR moving targets are verified by simulation and experimental tests.