Thesis Type: Doctorate
Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Electrical and Electronics Engineering, Turkey
Approval Date: 2015
Student: ÇAĞRI ÇETİNTEPE
Co-Supervisor: SEYİT SENCER KOÇ, ŞİMŞEK DEMİRAbstract:
Frequency diverse array (FDA) concept is one particular manifestation of waveform diversity, a topic which gains popularity among the research community in response to pressing demands of modern radar and communication systems such as multiple tasks, capacity and security. Introduction of a set of waveforms to the elements of an array, with slight shifts in the carrier frequencies so to establish frequency diversity, leads to far-field patterns that are remarkably different from conventional phased arrays, and opens up new possibilities like simultaneous missions, automatic beam scanning, range filtering, and flexible beamforming. Being a relatively new topic and lacking experimental demonstration in practical scenarios, the frequency diverse array concept lends itself to research opportunities from both theory and implementation perspectives. This thesis seizes these opportunities by proposing two possible applications for the FDA. First part of the thesis applies the FDA to a microwave link in a simple multipath propagation environment, establishes a theoretical framework to analyze its performance, and demonstrates potential improvement over a conventional phased array in mitigating harmful effects of multipath propagation. The second part then adapts the FDA to a monostatic radar configuration with a complex target, develops the theory to examine radar cross section (RCS) fluctuations as a function of target aspect, and shows more favorable RCS characteristics as an improvement over a conventional phased array. The thesis also encompasses experimental verification of these concepts with a practical FDA system. Measurement results obtained over a wide range of experimental parameters agree well with theoretical expectations.