Transmission Characteristics of Spherical TE and TM Modes in Conical Waveguides (Short Papers)
01 Nov 1974-IEEE Transactions on Microwave Theory and Techniques (IEEE)-Vol. 22, Iss: 11, pp 965-970
TL;DR: In this paper, the phase coherence between the dominant spherical TE and TM modes within the guide is investigated and an analytically simple and highly accurate digital-computer-based iterative algorithm has been employed to evaluate the eigenvalues associated with the spherical TE/sub 11/ modes.
Abstract: The transmission properties of spherical TE and TM modes in a perfectly conducting conical waveguide are treated in detail. To start with, an analytically simple and highly accurate digital-computer based iterative algorithm has been employed to evaluate the eigenvalues associated with the spherical TE and TM modes within the guide irrespective of the flare angle (2alpha/sub 0/) of the conical waveguide (theta < 2alpha/sub 0/ < 360/spl deg/). Subsequently, explicit expressions for the attenuation constant, phase constant, phase velocity, and wave impedance are obtained for the spherical modes transmitted within the guide. Accurate eigenvalues obtained numerically are used to study the variation of attenuation constant, phase constant, phase velocity, and wave impedance as a function of the radial distance from the apex with alpha/sub 0/ as a parameter. Measured data on the phase constant of a conical waveguide for the TE/sub 11/ mode have been compared with the analytical results obtained by calculation and an excellent agreement between the two justifies the validity of the analysis presented. Finally, a study of the phase coherence between the dominant spherical TE and TM modes within the guide is presented which may be fruitfully employed in the design of dual-mode conical waveguides.
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TL;DR: In this article, a waveguide taper concept is presented for low-precision radar measurements of liquid materials in large metal tubes, so-called stilling wells, bypass or still pipes.
Abstract: . This contribution deals with guided radar level measurements of liquid materials in large metal tubes, so-called stilling wells, bypass or still pipes. In the RF domain these tubes function as overmoded circular waveguides and mode-matched excitation structures like waveguide tapers are needed to avoid higher order waveguide modes. Especially for high-precision radar measurements the multimode propagation effects need to be minimized to achieve submillimeter accuracy. Therefore, a still pipe simulator is introduced with the purpose to fundamentally analyze the modal effects. Furthermore, a generalized design criterion is derived for the spurious mode suppression of compact circular waveguide transitions under the constraint of specified accuracy levels. According to the obtained results, a promising waveguide taper concept will finally be presented.
13 citations
TL;DR: The electromagnetic spatital distributions are analyzed and it is shown that all modes run continuously from a propagating through a transition to an evanescent region and the value of the attenuation increases as the distance from the cone vertex and the cone angle decrease.
Abstract: We analyze the electromagnetic spatital distributions and address an important issue of the transmission properties of spherical transverse-electric (TE) and transverse-magnetic (TM) eigenmodes within a tapered hollow metallic waveguide in detail. Explicit analytical expressions for the spatital distributions of electromagnetic field components, attenuation constant, phase constant and wave impedance are derived. Accurate eigenvalues obtained numerically are used to study the dependences of the transmission properties on the taper angle, the mode as well as the length of the waveguide. It is shown that all modes run continuously from a propagating through a transition to an evanescent region and the value of the attenuation increases as the distance from the cone vertex and the cone angle decrease. A strict distinction between pure propagating and pure evanescent modes cannot be achieved. One mode after the other reaches cutoff in the tapered hollow metallic waveguide as the distance from the cone vertex desreases.
4 citations
TL;DR: In this paper, a Chebyshev-Galerkin solution of the electric field integral equation for the surface current induced on a conducting frustum by an incident plane wave is presented.
Abstract: A Chebyshev-Galerkin solution of the electric field integral equation for the surface current induced on a conducting frustum by an incident plane wave is presented. The physically motivated mathematics takes proper account of the static singularity in the kernel function and of the edge conditions at both apertures, to yield complete and convergent current expansions. Coupling of the electromagnetic field into the tapered interior of the open scatterer can be substantial, even in electrically narrow cross sections, due to the focusing action of the conical transmission line. >
3 citations
TL;DR: In this article, a full analytical study of higher order modes in conical transmission lines is presented, and methods for the evaluation of these solutions are presented which combine a number of mathematical techniques and results.
Abstract: This article presents a full analytical study of higher order modes in conical transmission lines. Full analytical field solutions and modal cutoff equations are included, and methods for the evaluation of these solutions are presented which combine a number of mathematical techniques and results. Calculated numerical results and field distributions of some higher order modes in conical lines are shown. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.
3 citations
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TL;DR: In this article, a simpler solution for spherical hybrid modes in corrugated conical horns has been shown to have a deviation from the rigorous solution of less than 0.7 dB for the case considered by Clarricoats.
Abstract: A simpler solution for spherical hybrid modes in corrugated conical horns has been shown to have a deviation from the rigorous solution of less than 0.7 dB for the case considered by Clarricoats. Expressions for the radiation pattern and gain of such a horn with small flare angle have been obtained under balanced hybrid conditions.
33 citations