Design of directional and circular polarized antenna systems capable of receiving data from meteorology satellites

In this thesis, a circularly polarized microstrip patch antenna with two cross-shaped directors is firstly proposed. The patch antenna is first designed in the form of a traditional linear polarized antenna. Then, two opposed corners of the patch are truncated to give a circular polarization property to the antenna. Graphics with different frequency values have been obtained in the design phase. The antenna design was accomplished through the Comsol program. In the last design phase, two cross-shaped directors are added in front of the patch surface of the microstrip antenna to increase its gain. All adjustable geometrical properties of the antenna are optimized by parameter sweep method for each design phase. The antenna gain is increased from 3.99 dBi to 4.402 dBi with the help of the directors. After the gain improvement of the proposed antenna, its S11 and axial ratio characteristics are still in the desired range. The resonance frequency of the antenna is slightly shifted from 1700 MHz to 1705 MHz whereas AR remains below 3dB level successfully. This thesis also presents the design of a circularly polarized antenna system consisting of a pair of V-dipole antennas and a rod director operating at a center frequency of 137 MHz. For this design, firstly a single V-dipole antenna structure was evaluated. After the results were seen to be successful, a second V-dipole antenna in diagonal position with a quarter wave distance and reflective rods were included in the design. With this new design, 4.82 dBi maximum absolute gain and 0.51 dB axial ratio at 137 MHz were successfully achieved.