Abstract-The characteristics impedance of the fundamental mode in a rectangular waveguide is computed using finite element method. The method is validated by comparison with the theoretical results. In addition to this, we have considered the problem of determining the modes of propagation of electromagnetic waves in a rectangular waveguide for the simple homogeneous dielectric case. The starting point is Maxwell's equations with an assumed exponential dependence of the fields on the Z-coordinates. From these equations we have arrived at the Helmholtz equation for the homogeneous case. Finiteelement-method has been used to derive approximate values of the possible propagation constant for each frequency.
This paper presents a stacked rectangular dielectric resonator antenna design. In this structure, two sapphires having the same dielectric constant and different dimensions piled over each other have been used for designing the proposed antenna. The designed antenna exhibits two frequency bands from 7.41 GHz to 8.21 GHz and 9.11 GHz to 12.65 GHz and impedance matching of 50 ohms. The proposed antenna design is a fine choice for subterranean and rugged communication, in addition, owing to sapphires unique features viz. durability, endurance, and aversion to physical change. The antenna structure is aperture coupled. Due to the advantage of aperture coupled feed mechanism such as good isolation between antennas and feed networks it has been employed. The antenna prototype has been fabricated, measured, and tested using Vector Network Analyzer and Anechoic Chamber to validate the proposed antenna design. The simulation results obtained indicate close proximity of tested result.
For precision finishing of various newly and difficult of finish materials like optical glasses, metals, 3D-printed workpieces etc. Ball End Magnetorheological Finishing (BEMRF) finishing processes has been recently developed. This method utilizes a paste like fluid consisting of a base fluid which can be either water or oil, both magnetic and non-magnetic particles and stabilizing agents if necessary. Rheological behavior of this mixture of magnetorheological (MR) fluid with abrasives changes under the influence of magnetic field which in turn regulates the finishing forces during finishing processes. Present study critically reviews the BEMRF process used for achieving nano-level finishing variety of materials like mild steel, EN-31, copper etc. and the factors influenced this process so far which led to further advancements in this method.
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