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G.L. James

Bio: G.L. James is an academic researcher from Commonwealth Scientific and Industrial Research Organisation. The author has contributed to research in topics: Waveguide & Wideband. The author has an hindex of 2, co-authored 2 publications receiving 291 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, a theoretical parametric analysis of a TE/sub 11/-to-HE/sub11/ mode converter consisting of a section of cylindrical corrugated waveguide with varying slot depth is presented.
Abstract: A theoretical parametric study is given of a TE/sub 11/-to-HE/sub 11/ mode converter consisting of a section of cylindrical corrugated waveguide with varying slot depth. The analysis makes use of modal field-matching techniques to determine the scatter marks of the mode converter from which we deduce its propagation properties. It is shown that a mode converter consisting of only five slots achieves a return loss better than 30dB over the band 2.7

195 citations

Journal ArticleDOI
TL;DR: In this paper, a summary of the results of a mainly experimental investigation into the development of wideband orthomode transducers (OMTs) is presented, showing that satisfactory performance for many applications is possible over bandwidths in excess of 2:1.
Abstract: A summary of the results of a mainly experimental investigation into the development of wideband orthomode transducers (OMTs) is presented. It is shown that satisfactory performance for many applications is possible over bandwidths in excess of 2:1. The wideband return loss and cross-polarization behavior are given where the OMT used is measured in conjunction with a wideband corrugated horn. Two types of OMT are considered: one based on a finline technique and the other on a quad-ridged waveguide geometry. Overall, the latter design gives superior performance. >

111 citations


Cited by
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Journal ArticleDOI
TL;DR: In this paper, the angular power spectrum of the cosmic microwave background from l = 75 to l = 1025 was measured from a combined analysis of four 150 GHz channels in the BOOMERANG experiment.
Abstract: This paper presents a measurement of the angular power spectrum of the cosmic microwave background from l = 75 to l = 1025 (~10' to 24) from a combined analysis of four 150 GHz channels in the BOOMERANG experiment. The spectrum contains multiple peaks and minima, as predicted by standard adiabatic inflationary models in which the primordial plasma undergoes acoustic oscillations. These results, in concert with other types of cosmological measurements and theoretical models, significantly constrain the values of ?tot, ?bh2, ?ch2, and ns.

938 citations

Journal ArticleDOI
TL;DR: In this paper, a smooth-walled spline-profile horn for specific application in the 80-120 GHz band was proposed. But the results of a theoretical and measurement study of the smooth-wall spline profile horn were presented.
Abstract: At millimeter-wave frequencies, corrugated horns can be difficult and expensive to manufacture. As an alternative we present here the results of a theoretical and measurement study of a smooth-walled spline-profile horn for specific application in the 80-120 GHz band. While about 50% longer than its corrugated counterpart, the smooth-walled horn is shown to give improved performance across the band as well as being much easier to manufacture.

181 citations

Journal ArticleDOI
TL;DR: In this paper, the class of circularly symmetrical corrugated horns and the parameters in designing are considered. And some basic information for the inexperienced horn designer to get started in designing their CORRUGATED horn is provided.
Abstract: Typical example of horn is shown where the inside wall is manufactured in a succession of slots and "teeth". The purpose of the corrugated surface is to provide the means to support the propagation of hybrid modes within the horn. Hybrid modes are basically a combination of TE and TM modes. Some basic information for the inexperienced horn designer to get started in designing their corrugated horn is provided. The class of circularly symmetrical corrugated horns and the parameters in designing are considered. As an example a standard Ku-band operation from a typical Earth station is also considered.

144 citations

Journal ArticleDOI
TL;DR: In this article, a method for computing the resonant frequency in a complex cavity consisting of a series of waveguide sections is derived, restricted to transitions in which one waveguide is wholly contained in the other.
Abstract: A method for computing the resonant frequency in a complex cavity consisting of a series of waveguide sections is derived. The analysis is restricted to transitions in which one waveguide is wholly contained in the other. An eigenvalue problem is formed by cascading the scattering matrix from a given section outwards to the ends of the complex cavity, with appropriate boundary conditions at the ends. The eigenvalue equation is solved numerically by searching for a complex frequency, the cavity Q being determined by half of the ratio of the real to the imaginary part of the frequency. The technique is easily implemented numerically and shows good agreement with experiment. This method is suitable for modeling both abrupt changes in radius and smoothly varying tapers. >

127 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present an overview of the state-of-the-art of hybrid mode-matching (MM)/finite-element (FE)/method-ofmoments (MoM) and finite-difference (FD) techniques applied for the rigorous, fast computer-aided design and optimization of waveguide components, combline filters, and coupled horns.
Abstract: This paper presents an overview of the state-of-the-art of hybrid mode-matching (MM)/finite-element (FE)/method-of-moments (MoM)/finite-difference (FD) techniques applied for the rigorous, fast computer-aided design and optimization of waveguide components, combline filters, and coupled horns, as well as of slot arrays, and describes some recent advances Related aspects involve the inclusion of coaxial and dielectric structures for related filters, the extension to multiports at cross-coupled filters, the rigorous consideration of outer and Inner mutual coupling effects at coupled horn and slot arrays, the application of the multilevel fast multipole algorithm for the more efficient MoM calculation part of horns and horn clusters, and the utilization of the MoM for the design of arbitrarily shaped three-dimensional waveguide elements The described hybrid techniques combine advantageously the efficiency of the MM method with the flexibility of FE, MoM, and FD methods Topical application examples demonstrate the versatility of the hybrid techniques; their accuracy is verified by available measurements

99 citations