Time Reversal Performance Analysis When The Number Of Array Elements Is Limited

Time Reversal technology is the inverse operation process of signal in Timedomain, due to its special space-time focusing characteristics, it gain wideattention by the researchers. With the theoretical achievements of time reversaltechnology increasingly update, how to apply it to the specific engineeringpractice has been becoming the current hot issues at the same time. This thesisbased on the national natural science fund project: Key technology ofinformation extraction of metal tag based on electromagnetic detectiontechnology. It studies the time reversal technique under the finite number ofarray elements respectively from two points of view: transfer function and waveequation.First of all, the thesis introduced the basic theory of time reversaltechnology, which leads to the time-reversal cavity （TRC） and time-reversalmirror （TRM）. Then it discussed the basic research methods of time reversaltechnology: iterative time-reversal mirror（ITRM）, time-reversal multiplesignal classification （TR-MUSIC）and passive time-reversal mirror（PTRM）.Then the thesis mainly study the iterative time reversal mirror from theperspective of the transfer function, it focus on the performance of theapplication under the finite number of array elements. By establishing themathematical model, we use the MATLAB simulation tools to study the iterationtime reversal technology. Compare it’s performance with the multiple signalclassification （MUSIC） under the same conditions. In this thesis, we discussedthe influence of the iterative time reversal mirror’s performance on SNR, numberof array elements and the number of iterations. The simulation results show thatthe SNR, the number of iterations, number of array elements and the performanceof the iterative time reversal mirror are positive correlation. But according todifferent conditions, the impacts of the ITRM’s performance from the threeparameters are different.Finally, the thesis focuses on the performance of the application under thefinite number of array elements from the perspective of the wave equation. UsingMATLAB simulation tools to numerical simulate the Huygens principle, it provethe feasibility of time reversal technology in discrete array. After themathematical model of time reversal cavity is simulated, we discussed theinfluence of time-reversed focusing characteristics by the number of targets and the number of array elements. The analysis of simulation results show that, thenumber of targets does not affect the performance of time reversal. The numberof array elements has no impact on the focus performance, but as the number ofarray elements decrease, the peak value in the focal point is also decreased incase of strong complex noise environment, it can make the focus peak submergedby noise, leads to the time reversal can’t be focused.