Josaphat Laboratory graduated Dr. Merna Baharuddin with Ph.D. Thesis entitled “Development of microstrip antenna for circularly polarized synthetic aperture radar” on 25 March 2009. She is staff of University of Hasanuddin (Unhas) and receipient of Monbukagakusho Scholarship.
Abstract :
Synthetic aperture radar (SAR) is an active sensor that can produce high resolution imagery in microwave bands. The use of microwave frequencies enables penetration through clouds, and even through forest canopy for lower frequency bands. A circularly polarized SAR (CP-SAR) to be launched onboard a micro-satellite is currently developed in the Microwave Remote Sensing Laboratory (MRSL) of the Center for Environmental Remote Sensing (CEReS), Chiba University. As part of the project, an airborne CP-SAR development is also undertaken in order to obtain sufficient knowledge of CP-SAR sensor systems. An L-band CP-SAR system will be designed for operation onboard an unmanned aerial vehicle (UAV).
Conventional SAR systems have been based on linearly polarized (LP) antenna systems. However, there are limitations due to the propagation phenomena such as the variation of geometric distance between the radar system and the Earth, the occurrence of a phase shift when microwave strikes smooth, reflective surfaces, etc. Especially for space propagation, electromagnetic waves propagating through the ionosphere interact with electrons and magnetic fields. As a result, the polarization vector of the electric field is tilted by the Faraday rotation effect.The destructive effects mentioned above of a SAR sensor with linear polarization can be solved by the use of CP-SAR. The operational frequency is chosen to be 1.27 GHz in L-band considering its superior features on particular applications. To investigate the new SAR sensor with CP antennas, in this dissertation, CP microstrip elements are proposed and developed to be implemented in an array antenna for the CP-SAR sensor onboard an UAV. The numerical simulations and the measurement results are shown and discussed.