Design and development of wideband and dual band linear to circular polarization converters for space applications

Abstract

Polarization converters play a crucial role in various frequency ranges, offering advantages newlinesuch as reduced Radar Cross-Section (RCS), minimized interference, improved millimeterwave newlineimaging, and enhanced circularly polarized antenna performance. These applications are newlineincreasingly important due to rapid advancements in radar and satellite communication technologies. newlineRecently, metasurfaces, two-dimensional counterparts of metamaterials have gained newlinesignificant attention owing to their cost-effectiveness, conformability, and sub-wavelength newlinestructural characteristics. A metasurface consists of an array of sub-wavelength resonant structures, newlinewhere geometric parameters significantly influence Electromagnetic (EM) wave behavior. newlineBy carefully designing these structures, precise control over the amplitude and phase of newlinethe wave can be achieved. This thesis focuses on the design, development, and experimental newlinevalidation of metasurface-based wideband and dual-band polarization converters for space newlineapplications. newlineThe first contribution of this work is an ultrathin wideband polarization converter composed newlineof two modified L-shaped metallic elements arranged in an opposite configuration. This newlinestructure efficiently converts an incident linearly polarized wave into a circularly polarized newlinewave over a broad frequency range of 8.19 to 11.08 GHz, achieving a 3-dB Axial Ratio Bandwidth newline(ARBW) of 30%. The unit cell dimensions are 7×7×1.6mm3 (0.225and#955;×0.225and#955;×0.051and#955;), newlinewhere and#955; corresponds to the center frequency of the operational band. The proposed design is newlineclassified as an ultrathin Polarization Conversion Metasurface (PCM) as the thickness is significantly newlineless than and#955;/12. The anisotropic structure of the PCM makes it a promising option for newlinecommunication applications that require high accuracy and efficiency. Hence, the proposed newlinewideband PCM demonstrates significant potential for versatile applications in X-band radar newlinesystems, multibeam antennas, beam scanning antennas, vehicle speed detection, air traffic newlinecontrol, and weather monitoring