A rigorous integral equation formulation is made in this paper for the analysis of phased arrays of radiating slots fed by rectangular waveguides. The number of elements is assumed to be finite, and the integral equat...
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A rigorous integral equation formulation is made in this paper for the analysis of phased arrays of radiating slots fed by rectangular waveguides. The number of elements is assumed to be finite, and the integral equation used is that of the method of moments. According to the equivalence principle and magnetic field boundary conditions, an integral equation for obtaining slot surface equivalence magnetic currents is formulated. Then, the integral equation is rewritten into a matrix equation after the implementation of the method-of-moments procedure. The reflection coefficients as a function of scan angle of;and the inductive magnetic currents over, the array elements are analyzed and discussed in detail. (C) 2001 John Wiley & Sons, Inc.
At the ultra-high frequencies (UHF) common to portable radios, the mine tunnel acts as a dielectric waveguide, directing and absorbing energy as a radio signal propagates. Understanding radio propagation behavior in a...
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At the ultra-high frequencies (UHF) common to portable radios, the mine tunnel acts as a dielectric waveguide, directing and absorbing energy as a radio signal propagates. Understanding radio propagation behavior in a dielectric waveguide is critical for designing reliable, optimized communication systems in an underground mine. One of the major parameters used to predict the power attenuation in lossy waveguides is the attenuation constant. In this paper, we theoretically and experimentally investigate the attenuation constants for a rectangular waveguide with dielectric walls. We provide a new derivation of the attenuation constant based on the classic Fresnel reflection coefficients. The new derivation takes advantage of ray representation of plane waves and provides more insight into understanding radio attenuation in tunnels. We also investigate the impact of different parameters on the attenuation constant, including the tunnel transverse dimensions, permittivity, conductivity, frequency, and polarization, with an aim to find their theoretical optimal values that result in the minimum power loss. Additionally, measurements of the attenuation constants of the dominant mode at different frequencies (455, 915, 2450, and 5800 MHz) for a straight concrete tunnel are presented and compared to theoretical predictions. It is shown that the analytical results match the measured results very well at all four frequencies.
The mode matching solution of ferrite-loaded waveguide devices requires accurate knowledge of the pertinent modes. Computation of the propagating factor of such modes is essential but nontrivial. Here an efficient tec...
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The mode matching solution of ferrite-loaded waveguide devices requires accurate knowledge of the pertinent modes. Computation of the propagating factor of such modes is essential but nontrivial. Here an efficient technique for computing these factors for an arbitrary number of modes is presented.
A numerical analysis of a uniform rectangular waveguide filled by an inhomogeneous dielectric with a continuous spatial variation of the relative permittivity is presented in this Letter. The proposed method, based on...
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A numerical analysis of a uniform rectangular waveguide filled by an inhomogeneous dielectric with a continuous spatial variation of the relative permittivity is presented in this Letter. The proposed method, based on a method-of-moments (MoM) solution of the differential equations for TE, LSE. and LSM modes, is applied to find out the cutoff,frequencies of the waveguide. Some numerical examples are also presented, considering both continuous and stepped variations of the permittivity along a transverse direction. (C) 2002 Wiley Periodicals, Inc.
The experimental values of attenuation of commercially available rectangular waveguides were determined at frequencies between 25 and 200 GHz with emphasis on high accuracy. They were compared with the theoretical val...
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The experimental values of attenuation of commercially available rectangular waveguides were determined at frequencies between 25 and 200 GHz with emphasis on high accuracy. They were compared with the theoretical values computed from the dc conductivities, taking into consideration temperature effects, work hardening, size effects, surface roughness, and a room-temperature anomaly of the skin effect. A new way to express the excess attenuation due to these effects was fomulated. Excess ratios of attenuation of coin-silver waveguides were found to be well below the values used in engineering in the past. They can satisfactorily be explained by surface roughness. The normalized excess attenuations of copper guides are higher than those of guides made of silver but lower than cited in the literature.
The electrodynamic and numerical analyses of resonance phenomena in a junction of cylindrical and rectangular waveguides with a magnetodielectric are performed. The applicability of such a junction for nondestructive ...
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The electrodynamic and numerical analyses of resonance phenomena in a junction of cylindrical and rectangular waveguides with a magnetodielectric are performed. The applicability of such a junction for nondestructive measurements of the parameters of magnetodielectric specimens of cylindrical and rectangular cross sections is demonstrated.
The radiation impedance of an infinite array of open rectangular waveguides has been calculated by a function-theoretic method for H plane and quasi- E plane beam scanning directions. The mutual coupling between colum...
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The radiation impedance of an infinite array of open rectangular waveguides has been calculated by a function-theoretic method for H plane and quasi- E plane beam scanning directions. The mutual coupling between columns has also been obtained. The amplitudes of the coupling coefficients decay asymptotically as r^{-3/2} while the phase difference between successive coupling coefficients approaches that to be expected from free space wave propagation. This asymptotic behavior is independent of waveguide dimensions for both planes of scan. It is similar to the asymptotic behavior of a line-source-excited wave propagating over a lossy surface. This suggests that the interface between an array and free space may in general be treated as such a surface. The coupling coefficients are used to determine the properties of an array, which has a finite number of active elements surrounded by an infinite passive array. Also, the edge effect due to the finiteness of an array is evaluated.
A novel dielectric-filled metal-pipe rectangular waveguide has been fabricated using photoimageable thick-film materials. The waveguides incorporate a new transition from CPW-to-TFMS-to-MPRWG. Standard on-wafer measur...
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A novel dielectric-filled metal-pipe rectangular waveguide has been fabricated using photoimageable thick-film materials. The waveguides incorporate a new transition from CPW-to-TFMS-to-MPRWG. Standard on-wafer measurement techniques. waveguide STD calibration standards. demonstrated low attenuation across the 60 to 90GHz frequency range.
It is shown that dielectric plugs used to load the waveguides in a phased array can cause resonances such that a complete reflection takes place at certain scan angles. The difference in the characteristics of the res...
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It is shown that dielectric plugs used to load the waveguides in a phased array can cause resonances such that a complete reflection takes place at certain scan angles. The difference in the characteristics of the resonances as compared to those of arrays covered by dielectric slabs is also pointed out.
Based on the expressions for the dominant hybrid-mode fields in twisted rectangular waveguides, dispersion formulas with two perturbational factors have been derived theoretically. These factors correspond to the two ...
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Based on the expressions for the dominant hybrid-mode fields in twisted rectangular waveguides, dispersion formulas with two perturbational factors have been derived theoretically. These factors correspond to the two effects of the twist on the dominant wave propagation, respectively. The one expresses a shift in the cutoff frequency while the other expresses the effect of elongation in the transmission path. A set of 20-cm-long waveguides twisted uniformly by various multiples of 90° has been manufactured by the method of electroforming. The resonant frequencies of the respective waveguides have been measured as a transmission cavity in the 10-GHz band to obtain dispersion relations. Experimental results are found to be in good agreement with the theoretically derived formulas. The results of Lewin's theory are also compared with the present ones.
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