Dual-Band Reflectarrays Using Microstrip Ring Elements and Their Applications with Various Feeding Arrangements. (August 2006) Chul Min Han, B.S., Korea University Chair of Advisory Committee: Dr. Kai Chang In recent years there has been a growing demand for reduced mass, small launch volume, and, at the same time, high-gain large-aperture antenna systems in modern space-borne applications. Thi...

An investigation for the enhancement strategy of bandwidth performance and analysis of different types of losses associated with reflectarray antennas is presented in this paper. Studies are carried out using different commercially available dielectric materials with dielectric permittivity ( r) values ranging from 2.08 to 13 and loss tangent (tan ) ranging from 0.0003 to 0.025. The performance...

Dual-reflectarray configurations exhibits some advantages from both mechanical and electrical points of view with respect to reflector antennas. Dual-reflectarray antennas present a reduced volume and the capability of being easily folded. Furthermore, these antenna configurations provide phase control on both reflectarray surfaces [1], which can be used to improve the antenna performance for m...

A reconfigurable aperture-coupled reflectarray element is proposed for the realization of beam steering antennas, suitable for radar applications. Each reflectarray element is coupled to a microstrip line, which is loaded by a single varactor diode acting as a phase shifter element, thus providing a continuously variable reflection phase. A reduced size reflectarray unit cell is properly design...

A novel scheme is introduced to design the high gain beam scanning reflectarray antennas for limited scan range application. At first, various existing schemes for beam scanning reflectarray antennas design are reviewed and it is concluded that as a convenient design scheme, the feed displacement technique is preferred for limited scan range applications. In order to improve the scan range, a b...

Reflectarrays composed of resonant microstrip gold patches on a dielectric substrate are demonstrated for operation at terahertz frequencies. Based on the relation between the patch size and the reflection phase, a progressive phase distribution is implemented on the patch array to create a reflector able to deflect an incident beam towards a predefined angle off the specular direction. In orde...

A microstrip reflectarray is a flat reflector antenna that can be mounted conformally onto a spacecraft’s outside structure without consuming a significant amount of spacecraft volume and mass. For large apertures (2 m or larger), the antenna’s reflecting surface, being flat, can be more easily and reliably deployed than a curved parabolic reflector. This article presents the study results on a...

A simulation technique based on Finite-Difference TimeDomain (FDTD) is used to analyze mutual coupling effects in reflectarray environment. The neighbouring element method has the ability to analyze actual non-identical reflectarray unit-cell accurately compared to the traditional Floquet simulation which assumes all unitcell is identical. It is also found that the nearest neighbouring unit-cel...

The paper describes a theoretical investigation into a limited bandwidth operation of a microstrip reflectarray. Two main factors limiting the bandwidth are considered. One is related to the requirement of phase compensation to convert a spherical wavefront launched by a feed into a planar wavefront. The other one is linked to the limited phasing range of microstrip antenna elements. The two fa...

The monochromatic aberrations produced by the phase distribution reflected by resonant sub-wavelength metallic structures are studied both analytically and numerically. Even for normal incidence, the angular dependence of the re-radiated wavefront disturbs the overall performance of the reflectarray. This effect is modelled as combination of a linear and a cubic dependence. A complete numerical...