Research On In-Situ Measurement Technology Of System Radiation Emission Based On Non-Uniform Array

With the improvement of the electrification in various fields,the system under test(SUT)involves large volume and high power supply requirements.The test of the radiated emission signal cannot be carried out in the anechoic room,but can only be carried out in-situ.Due to the development of communication technology,the amount of ambient signals is increasing day by day,and the signals may also exceed the standard limit,which makes it impossible to accurately measure the radiated emission of the SUT.The test technology based on the array antenna can suppress the ambient signal and is an effective method to test the radiated emission of the SUT.At this stage,most of the antennas used in this method are linear uniform array antennas.The electromagnetic coupling between the array elements in the uniform array will cause mutual coupling errors in the received data,which will affect the accuracy of the signal degree of arrival estimation results and the suppression effect of ambient interference.In addition,when the number of signals in the environment is greater than the number of array elements of the uniform array,the number of array elements needs to be increased in the uniform array,which causes inconvenience to the in-situ test.Considering the advantages of nonuniform array elements such as large distance between array elements,low mutual coupling,and the ability to form virtual array elements,it is of great significance to carry out research on the measurement technology of SUT radiation emission based on non-uniform array.In this paper,the measurement method of SUT radiated emission based on symmetrically arranged non-uniform array structure is studied first.In the process of ambient signal identification,a blind source separation and spatial smoothing algorithm based on this structure is proposed,which can realize the function of decoherence and the number of estimated signals is larger than the number of array elements.In the signal suppression part,the MCMV algorithm can be used to ensure that the SUT signal will not be canceled under the premise of the existence of coherent signals,which makes up for the shortcomings of the MVDR algorithm.The radiation emission measurement method based on this array structure effectively realizes the suppression of the ambient signal and accurately measures the radiation emission of the SUT signal.Then,this paper studies the SUT radiation emission measurement method based on the two-level nested array structure.In the process of ambient signal identification,an improved sparse reconstruction algorithm is proposed based on the DCA of two-level nested arrays,which can decoherent well and the number of estimated signals is greater than the number of array elements.Meanwhile,a blind source separation and improved sparse reconstruction algorithm are proposed,which can obtain the incident angle information of coherent signals and provide input for beamforming.In the signal suppression part,the beamforming and adaptive noise cancellation methods can be used to suppress the ambient signals well when the number of ambient signals exceeds the number of array elements.Finally,the algorithm proposed in this paper is verified by algorithm simulation and experimental test.The simulation and experimental results show that the accurate measurement of SUT radiation emission can be achieved by using non-uniform array,which has a good reference value for in-site measurement of SUT radiation emission.