Polarization Analysis And Design Of Dual-band Dual-polarization Array Antenna

The dual-band dual-polarized array antenna shares a common radiation structure for receiving and transmitting signals,which can reduce the size and save the cost,and therefore it needs to have high polarization purity as well as transmitting and receiving isolation.All these properties require a reasonable choice of antenna structure and feed network layout in the design.In this thesis,the polarization characteristics of the antenna are studied and an array antenna with dual-band and dual-line polarization working in Ku-band is designed.The main work is as follows:1.This thesis proposes a cross-polarization measurement method based on two identical antennas to be measured and discusses the polarization characteristics of antennas and.For two antennas with unknown and identical radiation characteristics,the co-polarization and crosspolarization transmission coefficients are measured,and the antenna gain and cross-polarization level can be obtained by classifying the transmission channels in the measurement and statistics calculating based on Friis formula;the accuracy of this method is verified by using MATLAB for data processing and auxiliary calculation.2.An 8×8 elements Ku-band dual-band dual-polarization array antenna is designed and simulated in this thesis.According to the system index requirements,the antenna unit structure is determined,using the step horn form of the unit,which can obtain higher gain and uniform aperture field distribution.Besides,with the feed structure of the antenna unit designed separately,the transmit and receive feed structures located in different layers,and the orthogonal polarization,polarization isolation improves.Furthermore,the design of the feed network and the overall structure of the array antenna is completed in current research;the feed network adopts T-shaped structure for power division.The problems of impedance mismatch and power imbalance in the feed are solved by utilizing impedance transformation and impedance regulation.3.A 4×4 elements dual-band dual-polarized array antenna with higher cell gain was devised and processed for testing in this thesis.It turns out that this antenna still maintains good polarization purity and high port isolation.In addition,because of the higher gain of the antenna unit and deeper first zero point,the suppression of the gating-lobe also remains better,and the test results and simulation results are in good agreement.The Ku-band dual-band dual-polarization antenna designed in this thesis has high polarization purity and transceiver isolation,and has promising applications in satellite communication systems.