Application of Finite Difference Time Domain to Calculate the Transmission Coefficient of an Electromagnetic Wave Impinging Perpendicularly on a Dielectric Interface with Modified MUR-I ABC

MATLAB codes were implemented in this study for a one dimension wave formulation using the computational technique of finite difference time domain (FDTD) method. The codes have then been verified under two cases, one a simple one dimensional wave impinging perpendicularly on a dielectric layer from air interface and second is a one dimensional wave impinging momentarily on a small dielectric slab. The transmission coefficients under both the cases have also been verified. For the former case, there is a constant transmission coefficient irrespective of the frequency of the electromagnetic wave impinging on it and for the latter; there is a sinusoidal type variation due to multiple reflections along the wall of the dielectric slab. In the course of this implementation of the codes a novel technique to implement the absorbing boundary condition (ABC) on the dielectric interface has also been devised based on the Mur-I ABC which has been verified for a dielectric of dielectric constant 4єo. The implementation of the codes presents a recapitulation of the evolution of FDTD from Yee’s Algorithm to the latest modifications in the ABC.Defence Science Journal, 2012, 62(4), pp.228-235, DOI:http://dx.doi.org/10.14429/dsj.62.79

Return loss improvement of power splitter on EBG

58-61In the present paper, the improvement of the return loss of a power splitter/ divider, designed by partial removal of electromagnetic band gap (EBG) rods, has been investigated. The EBG used is a rod structure and shows a band gap in the range 2.2395 - 2.5774 GHz. The power splitter has a return loss of 2.45 GHz which falls in the range of the band gap. It has been found that a larger matrix of the EBG structure is needed in order to improve the return loss significantly. However, the removal of rods, as the matrix size is increased, needs to be done with a fixed ratio of the input feed length to coupling length in order to maintain the same resonant frequency. The improvement in the return loss has been significant from -19.932 dB (for a 5×5 matrix) to -37.214 dB (for a 17×17 matrix)