Contents I. Introduction
High gain antennas are desired in various applications, such as satellite communications, radar systems, and radio astronomy observations. Reflectarray and transmitarray antennas using printed circuit technology represent an attractive option for high gain antennas. Various reflectarray/transmitarray approaches have been described in the literature [1]-[5]. The transmitarray combines the features of lens and phased array antenna. When the transmitarray is in receiving mode, the transmitarray focuses the incident field from the aperture onto the feed; while in transmitting mode, the transmitarray collimates the radiation from the feed into a narrow beam [6], [7]. Each transmitarray cell element provides 3600 of phase variability with almost no change in the transmission magnitude as the insertion phase is varied. Dielectric resonator antenna (DRA) was first proposed by Long et al [8] in 1983. DRA have been of immense research interest because of their small size, low profile, wide bandwidth, high radiation efficiency due to the absence of conduction or surface wave losses and ease of excitation. Many investigations have been reported about the DRAs with different shapes and their characteristics have been examined [9]-[12].
