Browsing by Author "P.K. Choudhury"

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Comparative aspects of a metal loaded triangular waveguide with uniform and non-uniform distribution of Goell's matching points
(IETE, 1995) P.K. Shukla; P. Khastgir; S.P. Ojha; P.K. Choudhury
Using Goell's point matching method, a numerical analysis has been made of a Metal loaded Triangular Waveguide (MTW) with a non-uniform distribution of matching points, some of which are crowded near the corners of the triangle, and the results are compared with those reported earlier for an MTW with the matching points distributed in a uniform manner. An interesting aspect is observed that, as expected, a redistribution of the matching points without changing the total number of such points leads to a significantly different and better approximation to the modal characteristics than those obtained through a uniform distribution of points.
Cutoff characteristics of a chiroguide with parabolic cylindrical dielectric boundary
(Publ by Society of Photo-Optical Instrumentation Engineers, 1994) Sant P. Ojha; Kh.S. Singh; P. Khastgir; P.K. Choudhury
A recent structure of a guide is presented in which the guiding medium is filled with a chiral material and separated from the dielectric clad by a parabolic cylindrical boundary. The eigenvalue equation and the cutoff condition of such a guide have been derived. A possible application of the present analysis may be in the description of curved slab dielectric-chiral guides.
Exact analytical treatment of parabolically deformed planar waveguides near cutoff
(1994) P.K. Choudhury; P. Khastgir; S.P. Ojha; K.S. Ramesh
Using Maxwell's field equations a rigorous analytical treatment of a planar waveguide, in respect of its cutoff, has been attempted when it gets a slight parabolic deformation under the influence of any external cause. Comparison of the obtained results with that of an earlier published work on this problem confirms the mode-bunching phenomena to be the fundamental characteristics of such waveguides.
Modal power attenuation in a parabolically deformed planar waveguide near cutoff
(Wissenschaftliche Verlagsgesellschaft, 1995) P.K. Choudhury; P. Khastgir; S.P. Ojha; K.S. Ramesh
The cutoff characteristics of parabolically deformed planar waveguides are represented by complex propagation parameters. The real part of the complex propagation parameter β describes the propagation while the imaginary part gives the power attenuation of the particular mode. An analytical expression for the power attenuation is derived and the variation of the attenuation parameter from mode to mode has been estimated.
On the dispersion curves of a circularly deformed planar waveguide
(Wissenschaftliche Verlagsgesellschaft, 1995) P.K. Choudhury
A mathematical formulation has been made of a planar waveguide under a state of small circular deformation in transverse direction of the electromagnetic wave propagation. The scalar wave equation and the weak guidance approximation are used for the analysis, and the eigenvalue equation for the guide has been derived. A mode designation scheme, which is not conventional, is employed to present the dispersion curves for such a waveguide. It is found that these dispersion curves exhibit a partial resemblance with the existing curves for the various structures analyzed by other investigators. It is noticed that for higher order modes, the curves show the expected regular behaviour, while a curious and unusual behaviour is seen for the lower order modes.
Weak guidance in bent and unbent four-layer planar waveguidesa comparative study of dispersion curves
(1992) P.K. Choudhury; P. Khastgir; S.P. Ojha; L.K. Singh
A comparative study has been made of the dispersion curves of a four-layer bent and an unbent dielectric slab waveguide under the assumption of the weak guidance approximation. It has been noticed that the introduction of a slight bend to a planar waveguide results in mode-proliferation, and lower order modes show no cutoff at all. This anomalous behaviour of the dispersion curves is not seen in the case of an unbent waveguide structure. © 1992 The Japan Society of Applied Physics.