MIMO kablosuz haberleşme sistemleri için anten analizi/tasarımı ve yayılım kanalı modellemesi

Multiple-input-multiple-output (MIMO) wireless communication systems have been attracting huge interest, since a boost in the data rate was shown to be possible, using multiple antennas both at the transmitter and receiver. It is obvious that the electromagnetic effects of the multiple antennas have to be included in the wireless channel for an accurate system design, though they are often neglected by the early studies.In this thesis, the MIMO channel is investigated from an electromagnetics point of view. A full-wave channel model based on the method of moments solution of the electric field integral equation is developed and used in order to evaluate the MIMO channel matrix accurately. The model is called the channel model with electric fields (MEF) and it calculates the exact fields via the radiation integrals, and hence, it is rigorous except the random scatterer environment.The accuracy of the model is further verified by the measurement results. Thus, it is concluded that MEF achieves the accuracy over other approaches which are incapable of analyzing antenna effects in detail.Using the technique, MIMO performance of printed dipole arrays is analyzed. Effects of the electrical properties of printed dipoles on the MIMO capacity are explored. Appropriate dielectric slab configurations yielding high capacity printed dipole arrays are presented. The numerical efficiency of the technique allows analyzing MIMO performance of arrays with large number of antennas, and high performance array design in conjunction with well-known optimization tools. Thus, MEF is combined with particle swarm optimization (PSO) to design MIMO arrays of dipole elements for superior capacity. Freestanding and printed dipole arrays are analyzed and optimized.MIMO performance of printed rectangular patch arrays is analyzed using a modified version of MEF. Various array configurations are designed, manufactured, and their MIMO performance is measured in an indoor environment. The channel properties, such as the power delay profile, mean excess delay and delay spread, are obtained via measurements and compared with MEF results. Very good agreement is achieved.