Design and Development of Fractal Microstrip Antenna Arrays for Mimo Applications

Abstract

During last two decades, significant advancement is seen in wireless communication. To fulfil the increasing demands of users around the world higher data rate in in RF wireless communication system. It indicates that bandwidth enhancement is the main concern in the antenna design. In addition, compactness of design is equally important to place our antenna system easily in the modern communication devices. In the work presented, transmission line model is used for the simulation and analysis of slotted rectangular and triangular shaped patch microstrip antenna using feed line method. The reason behind this is to study the various parameters such as impedance bandwidth, radiation pattern and return loss of the presented antenna structure. Conducting patch with triangular shape is preferred due to the improved results over the rectangular patch antenna especially in the antenna arrays. Selection of length and width of the patch is very crucial parameter along with the dimensions of feed line. So in this thesis, a complementary sierpinksi gasket fractal antenna array for MIMO systems is designed at resonating frequency of 4.83 GHz, with the bandwidth of 408.2 MHz for WLAN application using CST Microwave Studio 10. Various parameters affecting the performance of MIMO antenna array such as envelope correlation coefficient, diversity gain are studied and physical parameters such as slot in the patch & DGS are also considered with its fabrication done. Also Compact triangular Patch microstrip fractal antenna array with defected ground structure is designed at resonating frequency of 5.6GHz, covering band 5.43-5.84GHz giving bandwidth of 418 MHz for WLAN application. Second order fractals are made in patch with optimized slot in ground plane, fabrication for this design is also done. Antenna parameters like ECC, diversity gain, bandwidth, return loss are determined. Both the fabricated wide band antennas are tested using VNA model no: E5071C. The testing results are shown along with the comparison between the simulated results and fabricated results. The operating frequency of single wide band at 4.83 GHz and 5.6 GHz is obtained at 4.38 GHz and 5.45 GHz respectively, also the range of frequencies covered by band has shifted to left side.