Conformal circular array antennas analysis and design

Radars which uses electromagnetic or acoustic waves are used for target determining, tracking and displaying and have a very important role in electronic defence systems. The most important part of the radars is clearly antenna. Array antennas are used for narrowing the beam, increasing the gain and the beam scattering in most of radar applications. The most characteristic part of the array antennas is the array pattern. Pattern consists of two main components such as main beam and side lobes. In order to avoid the interference effects, the side lobes are preferred as low as possible compare to main lobe. This is obtained when proper excitation coefficients are used for arrays? radiating elements. For this purpose, antenna feeding methods such as Taylor, Dolph-Chebysev, Bayliss, Binom are developed. This thesis includes circular and nonuniform array analysises for identification of friend of foe (IFF) systems.In this study, sum and difference pattern analyses are realized for circular array at horizontal plane. The circular array having simultaneously feeding elements is transformed a nonuniform array and element excitation coefficients are calculated by using a proper line source distribution. The obtained excitation coefficients are used in circular array and thus, side lobe suppression is realized for both sum and also difference beams.In this study, three circular arrays using different elements such as dipole Yagi and circular patch antennas are corresponding non-equispaced linear arrays are designed. A program is written in order to obtain the feeding amplitude distribution. Also usage of different antenna element?s effects on the radiation pattern is examined. The obtained results are given as graps.A non uniform patch array consists of sixteen radiating elements is designed and fabricated. To suppress the side lobe levels of the difeerence beam in the designed array antenna, the excitation coefficients are calculated by using the proposed method and a Microstrip power divider providing these coefficients is designed and fabricated. Also, a 180 degrees hybrid coupler is designed and fabricated to obtain the difference beam.