Application of Antenna Mode Switch and Polarization Diversity to Target Direction Finding and Recognition

摘要

In this dissertation delay-and-sum method minimum variance distortionless response method and antenna mode switch techniques are applied to target DOA (Direction-Of-Arrival) estimation After the target DOA is successfully estimated the antenna polarization diversity technique RCS (Radar Cross Section) and PCA (Principal Component Analysis) are further applied to identify the type of a target In the first part of this research two DOA estimation methods based on antenna mode switch techniques are utilized for improving the DOA estimation of incoming signals The improvement of DOA estimation is implemented on conventional delay-and-sum method and minimum distortionless response which are very simple and fast in calculation With the use of antenna mode switch techniques interferences from the antenna back lobe are greatly reduced and then the accuracy of DOA estimation is significantly improved Moreover the required size of an antenna array and its matrix calculation efforts can be decreased To practically implement the above concept a symmetric bow-tie antenna is proposed in this study By measuring its gain pattern and then taking the resulting data as input to the above improved DOA algorithms the results are very good and consistent with the simulation To give insight into the theoretical support we derived a novel formula to interpret the improvement of DOA estimation Our derived formula clearly shows how antenna back lobes significantly interfere the DOA estimation of incoming signals By this formula the influence of array element spacing and accuracy of DOA estimation can be predicted For the purpose of better accuracy the antenna mode switch is further combined with the minimum variance distortionless response method for DOA estimation of incoming signals It shows that the accuracy successful recognition rate and ability of tolerating noise are significantly improved With the use of such techniques the required array element number and element spacing are decreased After the DOA of an incoming signal is successfully estimated it further motivates us to identify the type of signal source i e to recognize the target In the second part of this research the radar target recognition is given based on polarization-diversity RCS and PCA signal processing The polarization-diversity of this study means changing the polarizations of incident waves and antennas Without loss of generality models of ships are used as targets of recognition for simplicity The RCS is simulated by ANSYS-HFSS software For consideration of better discrimination noise-reduction and easy computation the identification is implemented on PCA space Simulation results show that the polarization-diversity based target recognition scheme can accurately identify the type of a target with less efforts of measurement Simulation results also show that the proposed recognition scheme has good ability to tolerate random effects This dissertation is composed of seven chapters Chapter 1 presents an introduction of this study Chapter 2 gives basic theories utilized in this study Chapter 3 shows the delay-and-sum DOA estimation of incoming signals is improved by our antenna mode switch technique and shows how the concept is implemented by a practical antenna design In Chapter 4 we derive a novel formula for interpreting and predicting the improvement of DOA by using our antenna mode switch technique on delay-and-sum algorithms In Chapter 5 the DOA estimation of incoming signals by minimum variance distortionless response method and antenna mode switch technique is presented Chapter 6 shows the radar target recognition by polarization-diversity RCS on PCA space Finally conclusions of this research are given in Chapter 7

獎項日期	2015 2月 3
原文	English
監督員	Kun-Chou Lee (Supervisor)