Effects Of Mutual Coupling And Amplitude-phase Errors On The Ultra-Low Sidelobe Antenna

Modern electronic warfare has set higher demands for the low or ultra-low sidelobe antennas, which are key components of modern Radar. In this thesis, our work is focused on analyzing and compensating the effects of mutual coupling between elements of the thin dipole antenna array in naval ships.Firstly, the method of moment is employed to simulate the effect of mutual coupling between the elements. Chebyshev arrays are studied. The effects of mutual coupling on the ultra-low sidelobe antennas pattern synthesis are presented.Secondly, the Eigen-driven analysis method is presented, which takes into account of mutual coupling between elements. Monte Carlo method and the eigen-driven analysis method are combined to simulate the effects of errors on side-lobe level distribution of the Ultra-low side-lobe arrays.Thirdly, methods of compensating of mutual coupling effects are , introduced in detail. On the basis of MOM, a new definition of mutual compensating matrix is introduced and used to find the coupling-free signal voltages across the antenna terminal loads. Mutual coupling compensating matrix changes with the vertical direction of the signal. If a mutual coupling compensating matrix getting from a certain vertical direction is used to compensated the signal coming from other vertical direction, the mismatch may influence the compensating performance . It has been discussed in the thesis. A self-calibrating method for direction finding in the presence of mutual coupling ispresented. Calibration sources at known locations are not required. It takes advantage of imaginary part information of mutual compensating matrix. Simulating results show that the method can get enough precision to compensate mutual coupling effects.Fourthly, Technique for extension mutual coupling compensating matrix is presented. The mutual coupling data of small antenna array can be extrapolated to accurately predict that of larger antenna arrays.