محمدرضا نامجو

The primary aim of this thesis is to enhance image resolution in the range direction through antenna array optimization and selecting a suitable antenna element, considering optimization at a frequency of 9.9 GHz. Initially, it covers fundamental concepts in Synthetic Aperture Radar (SAR) systems. In Chapter 2, relationships influencing antenna size selection are discussed, followed by defining three key factors—NESZ (Noise Equivalent Sigma Zero), RASR (Range Ambiguity to Signal Ratio), and AASR (Azimuth Ambiguity to Signal Ratio)—which are crucial for image clarity. At the end of this chapter, several functions used for optimizing array antennas in SAR systems and a commonly used antenna element are studied. Chapter 3 describes the method, cost function, and the element employed in this thesis. In the final chapter, a comparison of using a suitable antenna element based on the optimization is provided. Image quality can be improved through processing techniques (using appropriate filters) or hardware adjustments (increasing amplifier power or low-noise amplifiers). Traditionally, attempts have been made to improve image quality by enhancing the antenna radiation pattern through various optimization methods. This thesis, besides optimization using conventional methods and eva‎luating responses, aims to utilize an element aligned with the radiation pattern for further improvement in end-view angles. As will be explained, the antenna’s signal-to-noise ratio decreases, and the noise level increases in the range direction at end-view points. The method demonstrated in this study reduces the range ambiguity signal ratio at the far end by approximately 2 to 3 dB.

آنتن آرايه‌اي، بهينه‌سازي، المان آنتن، ابهام در رادار دهانه روزنه‌اي

Array antenna, Optimization, Antenna element, Ambiguity in synthetic aperture radar

mohammadreza namjoo

Seyed Hassan Sedighy