A Broadband Reflectarray with combination of subwavelength phasing elements (original) (raw)
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On Radiation Performances of Reflectarray Antennas Constructed With Subwavelength Unit Cells
IEEE Antennas and Wireless Propagation Letters, 2015
Multi-element approach is utilized to increase the phase variation range of a square-ring sub-wavelength unit cell (UC) from 313° to more than 560°. Radiation characteristics of three thin reflectarray antennas (TRAs) constructed with the proposed UCs are investigated. This investigation demonstrates that to achieve a broadband highly efficient TRA, the employed λ/5-UC must have reflection loss considerably less than 0.1 dB and its constructing elements should also scatter the incident fields in the same fashion, i. e., the current distributions of all parts of the multi-element UC are of the same shape and cophased.
Design and Simulation of a Reflectarray Antenna using New Cell for Different Beam Angles
International Journal of Grid and Distributed Computing, 2016
In this paper a new cell is proposed for reflectarray antenna and is used to design the antenna to obtain to maximum gain and efficiency using phase synthesis in a frequency band of 11 GHz up to 11.7 GHz for different beam angles. The proposed cell is a double ring of hexagon which introduces multiple resonances which can provide more than 360 degrees phase variation by changing the loop size. Design method is based on phase-only algorithm where amplitude of the field on the reflectarray surface is forced by the feed. A 1.2 m reflectarray is designed for different beam directions. The results show maximum directivity of 42 dB and maximum efficiency of 73% for the required bandwidth. Focal length is 1.5 m which is set for maximum efficiency.
Bandwidth Improvement of Reflectarray Antennas Using Closely Spaced Elements
Progress In Electromagnetics Research C, 2011
A bandwidth improvement method in reflectarray antennas by using closely space elements, i.e., unit-cell sizes smaller than λ/2, has been investigated both numerically and experimentally in this paper. A new definition of phase error has been introduced to analyze the broadband mechanism of closely spaced phasing elements. Through full wave EM simulations, it is revealed that closely spaced elements achieve a smaller phase error over the band. Based on these theoretical studies two Ka-band reflectarrays were fabricated and their performance was measured across the frequency range of 30 to 34 GHz. It is demonstrated that the reflectarray designed with closely spaced elements achieves a notable improvement in gain bandwidth performance.
A Reflectarray with Octagonal Unit Cells for 5-G Applications
Wireless Personal Communications, 2017
In this paper, five suggested unit cells are presented and compared for the design of a 28-GHz reflectarray antenna that can be used for 5-G mobile base-stations. The unit cells of these reflectarrays are built with combinations between octagonal rings and octagonal patches. The CST microwave studio is used in all design stages. All reflectarrays have an area of 10k 9 10k with element size k/2 9 k/2 and focal length equal to 10k. A reflectarray antenna with size 15k 9 15k is built for one of the unit cells with element size k/2 9 k/2 and focal length 10k to enhance the gain. Center feeding is used with a pyramidal horn antenna. Simulation results show that the unit cell composed of two octagonal rings with an octagonal patch inside gives a high gain with a quite large bandwidth.
IEEE Transactions on Antennas and Propagation, 2013
A dual-offset reflectarray demonstrator has been designed, manufactured and tested for the first time. In the antenna configuration presented in this paper, the feed, the subreflectarray and the main-reflectarray are in the near field one to each other, so that the conventional approximations of far field are not suitable for the analysis of this antenna. The antenna is designed by considering the near-field radiated by the horn and the contributions from all the elements in the sub-reflectarray to compute the required phase-shift on each element of the main reflectarray. Both reflectarrays have been designed using broadband elements based on variable-size patches in a single layer for the main reflectarray and two layers for the sub-reflectarray, incident field. The measured radiation patterns are in good agreement with the simulated results. It is also demonstrated that a reduction of the cross-polarization in the antenna is achieved by adjusting the patch dimensions. The antenna measurements exhibit a 20% bandwidth (12.2GHz-15GHz) (with a reduction of gain less than 2.5 dB) and a cross-polar discrimination better than 30 dB in the working frequency band. Index Terms-Reflectarray, cross-polarization reduction, broadband reflectarray and dual-reflectarray I. INTRODUCTION EFLECTARRAY antennas have demonstrated their benefits with respect to classic reflector antennas for certain applications. Reflectarrays exhibit capabilities to provide high-gain focused beams in large apertures [1], contoured
Broadband reflectarrays made of cells with three coplanar parallel dipoles
Microwave and Optical Technology Letters, 2014
A broadband reflectarray cell made of three parallel dipoles printed on a dielectric layer is presented. A 33% bandwidth is achieved for the cell made of dipoles, which is larger than that obtained for a reference cell consisting of three stacked square patches (26%). Using this cell, a 41-cm reflectarray antenna has been designed to produce a collimated beam at 9.5 GHz. The numerical results obtained for the reflectarray antenna made of parallel dipoles show a 1-dB bandwidth of 19%, a 65% efficiency, 0.2 dB of losses, and low levels of cross polarization (25 dB below the maximum). These results demonstrate a high performance for the proposed reflectarray antenna made of cells with three printed dipoles.
Modified Phasing Element for Broadband Reflectarray Antennas
Progress In Electromagnetics Research C, 2017
New phasing element for a wideband microstrip reflectarray is presented. It is formed by a phase-delay line attached to a circular ring loaded with a circular disc microstrip. The structure is enclosed by a circular ring element with a pair of gaps. It is shown that the new phasing element offers a wider bandwidth with an increased phasing range that is useful in reflectarrays phase compensation procedure. Full wave EM simulations are carried out. Good agreement exists between simulation results and measurements by using waveguide simulator method. The mutual coupling effect for a realistic reflectarray configuration with non-identical cells is accounted for by using the perturbation technique.
Iranian Journal of Science and Technology, Transactions of Electrical Engineering, 2019
This paper presents two designs of reflectarrays with two different unit cells: a novel broadband microstrip unit cell and a 3D all-metal unit cell. The microstrip unit cell consists of two concentric octagonal rings plus an octagonal patch with an empty cross inside. On the other hand, the all-metal unit cell is composed of a pure copper cuboid. These reflectarrays are designed to work around 28 GHz for suitable 5G operation. A pyramidal horn antenna is used for the feeding purpose. The F/D ratio is equal to one. The reflectarray is 107 mm × 107 mm in dimensions. The simulation results show that the reflectarray based on the microstrip unit cell achieves a 1-dB gain-bandwidth of about 31.2% with a gain equal to 27.2 dB at 28 GHz. On the other hand, the all-metal reflectarray achieves a 1-dB gain-bandwidth of 14.5% and a gain equal to 28.5 dB at 28 GHz. From the obtained results, it is clear that the microstrip reflectarray is superior from the gain-bandwidth perspective, while the allmetal reflectarray is superior from the gain perspective. The microstrip reflectarray has been fabricated, and its performance has been measured. A good agreement between the simulation and measurement results has been achieved.