Bifocal dual reflectarray with curved main surface

This paper presents a novel approach to synthesizing curved reflectarrays using Geometrical Optics (GO). It introduces the concepts of virtual normal and path length shift, which enable a vector-based formulation of the problem that can be solved using ray tracing techniques. The formulation is applied for the design of two different versions of a Dual Bifocal Reflectarray with a parabolic main surface and a flat subreflectarray. The first version aims to enhance the performance of the multibeam antenna by providing a focal ring located at the feed cluster plane. The second version focuses on improving the scanning characteristics of the antenna in the horizontal plane by incorporating two foci. The synthesis procedure yields samples of the path length shift or its derivatives. To reconstruct the phase distribution, an interpolation scheme is employed and described in this paper. Numerical results are presented for both the focal-ring and two-foci configurations, demonstrating the feasibility of this solution for multibeam or scanning satellite antennas operating in the Ka.European Space Research and Technology Centre | Ref. 4000117113/16/NL/AFMinisterio de Economía y Competitividad | Ref. PDC2021-120959-C21/C22Ministerio de Ciencia e Innovación | Ref. RYC2021-033593-IXunta de Galicia | Ref. GRC-ED431C-2019/2

EFFECT OF COPPER SULPHATE PENTAHYDRATE (CuSO4·5H₂O) AND RHIZOBACTERIA ON THE GERMINATION OF ROSELLE (Hibiscus sabdariffa L.)

Background: Heavy metals are perceived as the most persistent and dangerous. Cu is essential for plants, in excess it causes detrimental effects on plants and human health. Plant growth promoting bacteria have been mainly used in agriculture to promote seed germination, plant vigor and growth, and improve crop yields. Objective: To analyse the effect of germination in two roselle varieties that were inoculated with extracellular plant growth-promoting rhizobacteria of the genus Pseudomonas and in seven solutions of copper sulphate pentahydrate. Methodology: Roselle seeds were germinated in copper sulphate solutions, the seeds were inoculated with bacterial suspensions of two strains of Pseudomonas M40 and M67, the germination percentages were determined and vigour tests were also carried out. Results: The effect of copper sulphate on germination was significant in the interaction between main factors, but no significance was found in the effect of the strains and their interaction with the varieties. In the vigour tests, significance was detected between factors of stem dry weight, root and stem length, and strains. Implications: The tolerance of the seeds to copper sulphate, to know if it has an effect of promoting germination or, on the contrary, inhibits it. Conclusion: copper sulphate has the effect of promoting the germination of roselle seeds. Jamaica has a potential effect of phytoremediation of metals in combination with the inoculation of rhizobacteria that promote plant growth