Murad, Ridwan (PhD)Zewdie, Ayalew2020-10-092023-11-282020-10-092023-11-282020-01http://etd.aau.edu.et/handle/12345678/22634Side lobe suppression is one of the most important design considerations of linear antenna array to reduce interference and wastage of radiation power. Side lobe level reduction also avoid indicating false target. The reduction of side lobes can be achieved by proper calibration of inter element spacing, excitation amplitude or both inter element spacing and excitation amplitude at a time. In addition to these commonly used methods of side lobe suppression, changing the orientation of selected elements by rotating them about the normal of the array axis can change the polarization of the element pattern. This technique can produce polarization variation as compared with uniformly oriented elements. The purpose of the rotation of elements is to create interference in the side lobe direction of non-rotated array elements. Due to this created interference, the side lobe level of the whole array can be suppressed. This thesis presented side lobe level suppression of linear antenna arrays employing rotation of array elements. Simulations were performed using MATLAB and genetic algorithm optimization tool has been used to find angle of rotation, inter element spacing and excitation amplitude. Employing rotation of symmetrically positioned array elements, side lobe levels of -17.15dB for uniformly spaced & uniformly excited linear array, -20.40dB for non-uniformly spaced & uniformly excited linear array, -27.25dB for uniformly spaced & non-uniformly excited linear array and finally -28.02dB for non-uniformly spaced & non-uniformly excited linear arrays have been obtained, as can be seen on result, for a total of 10 array elements. As compared to radiation pattern of uniform linear arrays without rotation of elements, the obtained results show significant reduction of side lobe level. As a result of this side lobe reduction, energy wastage and interference outside of the main beam can be minimized with considerable amount and the performance of the array can be improved.en-USAntennaSide lobe levellinear arrayelement spacingexcitation amplitudeuniform spacinguniform excitationangle of rotationpolarizationrotationThesis