Design and Analysis of Wideband Reflectarray Antenna

Abstract

In recent years, reflectarray antennas are receiving more attention by the antenna research community. This is due to their low profile, reliable folding mechanism; low-cost chemical etching process features any many such advantages. However, the narrow bandwidth performance is the only drawback of the reflectarray antenna which limits its use in many practical applications. In fact, two different parameters control the bandwidth of the reflectarray antenna, (i) the narrow bandwidth of the radiating elements and, (ii) the spatial phase delay bandwidth. This thesis focuses on the spatial bandwidth enhancement.

A flat reflectarray antenna is designed at the design frequency of 10.7 GHz. The performance parameters of the antenna-like phase-shift distribution, radiation patterns, and directivity are discussed. The effects of the feed displacement and frequency change on the aperture phase and radiation patterns of the reflectarray antenna are studied and the outcomes are listed in the thesis. The design and analysis of the multifaceted reflectarray antenna are presented for spatial bandwidth improvement. The faceted configuration of the reflectarray antenna is achieved by segmenting the flat surface of the reflectarray antenna. For optics design of multi-faceted RFA, multiple panels are arranged on the tangents of the parabolic curve surface. This type of arrangement reduces the path length deviations. Using Geometric Optics (GO) based technique, phase shift distribution, radiation patterns, and directivity of the multifaceted reflectarray antenna are computed. For 3-panel and 5-panel faceted configuration of the reflectarray antenna, 1-dB gain bandwidth of 6.5% and 7.4% are obtained, respectively. The comparison of different configurations of the reflectarray antenna is presented in the thesis. It is demonstrated that the faceted configuration of the reflectarray antenna improves the spatial bandwidth. The design and analysis of a double circular ring are demonstrated with a phase rang of 487°. In addition to this, the design of an array of radiating elements is also introduced. The phase error distribution is discussed in this thesis based on Zernike polynomials. This dissertation also introduces the relationship between Zernike polynomials and aberrations. Using the Zernike polynomials, the phase correcting surface is optimized by correcting the coma aberration. The use of third-order Zernike polynomial is shown to suppress the coma aberration.