Abstract-Circularly polarized superquadric dielectric resonator antenna is investigated. A single coaxial probe is used to excite circularly polarized patterns. Finite element method is used to analyze the problem. Different aspect ratios of the superquadric dielectric resonator cross section for each squareness parameter for circular polarization are calculated.

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The plasma reflectarray/transmitarray antenna is a planar array, which reflects/transmits the incident fields radiating from a feed antenna. The plasma introduces a reconfigurable material for antenna applications. The proposed reflectarray/transmitarray unit cell consists of two plasma cylindrical ring tubes positioned along the top and bottom of a plasma square ground plane filled with argon gas. By controlling the ionized plasma gas density of the square ground plane, two modes of operations are obtained, reflectarray and transmitarray modes for the same unit cell. A 13 × 13 unit cell reflectarray/transmitarray antenna covering an area of 13.52×13.52 cm 2 is proposed. The dimensions of the unit cells are identical with different argon gas densities according to the relative phases of the reflected/transmitted wave. The reflectarray is operating at 19.39 GHz, while the transmitarray is designed for 19.75-GHz applications. The radiation characteristics of the reflectarray/transmitarray single structure have been investigated. The gain and frequency bandwidth for the new configurations are presented. An electronic beam steering plasma transmitarray antenna from −30°to +30°is introduced. A full-wave analysis using the finite integration technique is used for design and analysis of the plasma reflectarray/transmitarray antenna.

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Abstract-This paper addresses the design of fractal antennas placed onto dielectric object in the UHF RFID band and introduces a tag antenna configuration of simple geometry having impedance tuning capability. Through the paper, the dimensions of the fractal antenna are optimized to improve the impedance matching with the chip impedance. The tag performance changes are studied when it is placed on different objects (e.g., cardboard boxes with various content), or when other objects are present in the vicinity of the tagged object. It has been shown that a tag antenna can be designed or tuned for optimum performance on a particular object. Using the finite element method the open circuit voltage and the polarization mismatch factor against the operating frequency are calculated. The input impedance, reflection coefficient, power transmission coefficient and the read range as a function of frequency are illustrated. The performance of the tag antenna in the presence of the dielectric box and different object materials inside the box is illustrated. The effect of the objects that are placed in the center of the dielectric box didn't have a significant effect on the performance of the tag antenna; there is a small shift in the resonance frequency but still within the operating frequency band. Both the power transmission coefficient and the read range change with the object material. The backscattering properties of the tag antenna have been studied. The differential radar cross-section of the tag antenna is calculated for different antenna loads.Corresponding author: H. A. Malhat (er honida@yahoo.com). 210Zainud-Deen, Malhat, and Awadalla

Abstract-In this paper, the radiation characteristics of the singleelement cylindrical dielectric resonator antenna mounted on the surface of a metallic hollow circular cylindrical structure is investigated. The effect of the radius of curvature on the return loss, input impedance, standing wave ratio, and radiation pattern is explored. Mutual coupling between two identical cylindrical dielectric resonator antennas on a cylindrical structure in different configurations is determined. To reduce the mutual coupling between the two antennas, the surface of the cylinderical ground plane is defected by cutting slots, or inserting quarter wavelength grooves between the two antennas. The finite element method and the finite integration technique are used to calculate the radiation characteristics of the antenna.

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