Ridged Circular Waveguide Research Articles

Dispersion Analysis and Material Property Identification of a Circular Piezoelectric Ridge Waveguide

Abstract This study investigates the dispersive properties of ridge waves that travel circumferentially around piezoelectric circular ridge waveguides and investigates their resonant modes. Based on the variable separation method and Hamilton's principle, the displacement of ridge waveguides is represented as the product of a cross-sectional coordinate-dependent function and the propagator along the circumference of a circular ridge waveguide. The dispersion curves of the flexural waves and resonant frequencies corresponding to ridge waveguides are solved numerically by applying the bidimensional finite element method (Bi-d FEM) and using the three-dimensional (3D) ansys package. The estimated impedance curves are compared with the predicted dispersion curves of waves from ridge waveguides to validate the proposed numerical approach. The elastic constants of the circular piezoelectric ridge waveguide are determined through an inverse scheme that is based on the modified simplex method. The numerical and experimental results show that by using the modified simplex method to inverse calculate the elastic constants and geometric parameters of the piezoelectric circular ridge waveguides, a good degree of accuracy and sensitivity can be achieved.

Compact Relativistic Magnetron With Omnidirectional Radiation Through a Slotted Waveguide Array Antenna

A compact relativistic magnetron (RM) system with diffraction output is proposed, whose novelty lies in the omnidirectional radiation through the slotted waveguide array antenna. In the array antenna, a periodically slotted ridged circular waveguide is employed to obtain omnidirectional radiation and decrease its radius. Meanwhile, the RF field is directly coupling and radiating without complex mode conversion. Moreover, the interaction resonant system applies a ten-cavity rising-sun slow-wave structure to optimize the dispersion characteristics of the operating mode. The particle-in-cell simulations demonstrate that the RM could achieve 70% device efficiency and gigawatt radiation with an operating voltage of 400 kV. Besides, the output RF field is omnidirectional radiating with a gain up to 12.77 dBi at the operating frequency of 1.32 GHz, which is likely to be used in the high-power microwave area defense.

Compact ${L}$ -Band Relativistic Magnetron With Diffraction Output of TEM Mode

A compact ${L}$ -band relativistic magnetron (RM) with the diffraction output (DO) of the TEM mode is proposed. In this DO configuration, a ridged circular waveguide is used to replace the cylindrical waveguide to decrease its radial dimension. The RF field of the operating $\pi $ -mode is extracted from every resonator cavity and guided to the ridged circular waveguide. Even at the operating frequency of 1.55 GHz, the ridged circular waveguide can reduce the cutoff radius of the RF wave to 73 mm. The output RF field is further effectively converted to the TEM mode by a compact mode converter. Moreover, in the resonant system, a 10-cavity rising-sun slow wave structure (SWS) is applied to lower the phase velocity of the operating spatial harmonic and enhance the mode separation between the operating mode and the adjacent mode. The particle-in-cell (PIC) simulations demonstrate that the practical RM could output a relatively pure TEM mode at the frequency of 1.55 GHz, and its total efficiency is up to 60% with gigawatt radiation power for a diode voltage of 400 kV.

Uniform Field Resonators for EPR Spectroscopy: A Review.

Cavity resonators are often used for electron paramagnetic resonance (EPR). Rectangular TE102 and cylindrical TE011 are common modes at X-band even though the field varies cosinusoidally along the Z-axis. The authors found a way to create a uniform field (UF) in these modes. A length of waveguide at cut-off was introduced for the sample region, and tailored end sections were developed that supported the microwave resonant mode. This work is reviewed here. The radio frequency (RF) magnetic field in loop-gap resonators (LGR) at X-band is uniform along the Z-axis of the sample, which is a benefit of LGR technology. The LGR is a preferred structure for EPR of small samples. At Q-band and W-band, the LGR often exhibits nonuniformity along the Z-axis. Methods to trim out this nonuniformity, which are closely related to the methods used for UF cavity resonators, are reviewed. In addition, two transmission lines that are new to EPR, dielectric tube waveguide and circular ridge waveguide, were recently used in UF cavity designs that are reviewed. A further benefit of UF resonators is that cuvettes for aqueous samples can be optimum in cross section along the full sample axis, which improves quantification in EPR spectroscopy of biological samples.

Output switching in a semiconductor circular ring resonator due to solitons wave formation

Here we demonstrated the phenomena of switching of the coupling in an InGaAlP multiple-quantum-well semiconductor circular ring resonator due to the generation of solitons wave guiding. The fabricated device is consisted of a circular ridge waveguide ring resonator with diameter range from 150 to 250 µm with two Y-junction directional couplers for output coupling of clockwise/counter clockwise (CW/CCW) modes. Ridge waveguide of 1.1 and 0.8 µm depth were fabricated to study the effect in solitons generation. It showed that for the 1.1 µm etched depth waveguide, CW and CCW modes in the ring resonator were coupled out through each Y-junction couplers respectively. However, for the 0.8 µm depth waveguide when spatial solitons was formed, coupling of the CCW modes in the circular ring resonator was switched from Y-junction coupler to the spatial solitons guiding terminal. Measurements of light–current (L–I) and spectral characteristics were studied to enunciate the mechanism of output modes switching in circular ring resonator.

ANALYSIS OF A QUADRUPLE CORNER-CUT RIDGED/VANE-LOADED CIRCULAR WAVEGUIDE USING SCALED BOUNDARY FINITE ELEMENT METHOD

This paper presents an extension of the recently-developed e-cient semi-analytical method, namely scaled boundary flnite element method (SBFEM) to analyze quadruple corner-cut ridged circular waveguide. Owing to its symmetry, only a quarter of its cross- section needs to be considered. The entire computational domain is divided into several sub-domains. Only the boundaries of each sub- domain are discretized with line elements leading to great ∞exibility in mesh generation, and a variational approach is used to derive the scaled boundary flnite element equations. SBFEM solution converges in the flnite element sense in the circumferential direction, and more signiflcantly, is analytical in the radial direction. Consequently, singularities around re-entrant corners can be represented exactly and automatically. By introducing the \dynamic stifiness of waveguide, using the continued fraction solution and introducing auxiliary variables, a generalized eigenvalue equation with respect to wave number is obtained without introducing an internal mesh. Numerical results illustrate the accuracy and e-ciency of the method with very few elements and much less consumed time. In∞uences of corner-cut ridge dimensions on the wave numbers of modes are examined in detail. The single mode bandwidth of the waveguide is also discussed. Therefore, these results provide an extension to the existing design data for ridge waveguide and are considered helpful in practical applications.

Soliton Generation in a Semiconductor Circular Ring Laser with a Y-Junction Coupler

We report the observation of the emission of solitons from a semiconductor circular ridge waveguide ring laser with a Y-junction coupler. The light–current (L–I) characteristics of the soliton emission through the nonwaveguide region, which refers to the photovoltaic solitons, has a low threshold value and a high quantum efficiency compare to the emission from the Y-junction coupler, and the spectrum of the soliton emission is similar to that of a linear strip laser with multimode emission. The feedback light from the end facet of the Y-junction coupling section continuously enhances the excitation of the photovoltaic solitons through the nonwaveguide region until the lasing condition is reached. It is suggested that the circular ring laser can be an alternative channel to light wave control in integrated optoelectronic system.

Efficient Analysis of Quadruple Corner-Cut Ridged Circular Waveguide by Hybrid Mode-Matching Boundary-Element Method

This paper presents an efficient analysis of a circular waveguide with quadruple corner-cut ridges using a hybrid mode-matching (MM) boundary-element method (BEM). The electromagnetic field components in the regular region are obtained by the MM method, and the irregular region is modeled by the boundary element method. This hybrid technique takes advantage of the MM method's high efficiency and the BEM's versatility. Numerical results obtained by our hybrid MM-BEM agree very well with those obtained by a commercial finite-element software package. The influence of the cut corner on the single-mode operation bandwidth of a quadruple ridged circular waveguide is also examined.

Analysis of ridged elliptical waveguide by polynomial representation

Application of ridged rectangular and circular waveguides has been found in many areas. In this paper，with the Rayleigh-Ritz method and polynomial representation，the wave propagation characteristics in the ridged elliptical waveguide are analyzed. The numerical results are in good agreement with calculation using electromagnetic field simulation software. The variation of bandwidth with physical dimensions has been studied. It is helpful for optimizing this kind of structure.

InGaAs-GaAs 980-nm stripe-geometry and circular ring ridge waveguide lasers fabricated with pulsed anodic oxidation

In/sub 0.22/Ga/sub 0.78/As-GaAs quantum-well stripe-geometry and circular ring lasers have been fabricated with pulsed anodic oxidation (PAO). The relationship between ridge heights and laser performance was first studied in the fabrication of stripe lasers. The lowest transparency current density (J/sub tr/) of 61.20 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> was obtained from the stripe laser with a ridge height of 1.23 μm, corresponding to an etching depth where all the p-doped layers above active region were removed. With the PAO process, when the ridge height (1.77 μm) extended below the active region, J/sub tr/ is 76.03 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , only increased by 24.2%. Based on the experimental results, the circular ring laser, which needs deep etching (below active region) and subsequent PAO, has been fabricated. The fabricated circular ring laser worked under continuous-wave operation at room temperature. Longitudinal mode spacing analysis clearly indicates that the ring resonator is a functional part of the whole circular ring laser.

Propagation characteristic analysis of ridged circular waveguide using 2D finite-difference frequency-domain method

The propagation characteristics of ridged circular waveguides are analyzed by using 2D finite-difference frequency-domain (2D FDFD). Based on the 2D FDFD method in a cylindrical coordinate system, general difference formulas for the ridged circular waveguide are deduced, and modified difference formulas are built at some special points of the ridged circular waveguides. To verify the proposed method, three ridged circular waveguide structures are investigated and the numerical results are compared with available ones obtained by other research methods. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE 15, 2005.

Systematic elaboration of trial function bases for the study of ridged circular waveguide discontinuities polarizer

AbstractThis paper presents a mixed method for the characterization of ridged circular waveguide discontinuities. The method is based on integral equations in combination with a scalar Green's function and a boundary element method for the calculation an arbitrary ridged circular waveguide's mode spectrum. The modes computed by this technique are used as trial function bases for the characterization of arbitrary ridged circular waveguide discontinuities. An improved variational multimodal formulation is used for the characterization of the step discontinuity. Coupling coefficients are evaluated by post processing of the matrices already used in the modes' determination, and the overall scattering matrix is obtained by cascading the impedance matrix of such a discontinuity. In order to validate this method, screws used in filter design and spectrum polarizer are modeled and the numerical results are verified by excellent agreement with published data. © 2002 Wiley Periodicals, Inc. Microwave Opt Technol Lett 35: 478–482, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10643

Analysis and design of circular ridged waveguide components

A fast and efficient radial mode-matching technique (RMMT) is applied to the analysis and design of components in circular ridge waveguide technology. Five different structures are investigated with respect to their performance as filters and polarizers. For fast computation, pie-shaped metal ridges and septa are assumed to better fit the cylindrical coordinate system. In practice, the pie-shaped structures are approximated by rectangular cross-section metal inserts. The validity of this approximation is investigated by comparing with measurements and finite-element analysis. It is found that for thin etchable inserts, the measured filter response is in excellent agreement with the theoretical prediction and that for polarizers, the axial ratio response is not particularly sensitive to the ridge shape. Differences between computed and measured results occur only at return loss and isolation levels beyond 25 dB. A central processing unit time comparison with HFSS (4.0) results in a 10-min versus 3-h advantage in favor of the RMMT.

Fast and accurate mode-spectrum analysis of waveguide structures using a new set of edge-conditioned basis functions

A new set of edge-conditioned basis functions is used to determine the modal characteristics of a large variety of nonstandard waveguide structures. Since the electromagnetic field includes the proper edge conditions at metallic corners and since the new basis functions are readily Fourier transformed, a considerable reduction in computational effort with respect to standard modal field-matching techniques is observed. Similar to procedures involving other known sets of applicable basis functions, the analysis achieves a higher reliability level, as it completely avoids relative convergence phenomena. The method is demonstrated at the examples of several waveguide structures, such as the L-shape, T-shape, and cross-iris-shape waveguides; the rectangular coaxial waveguide; and the ridged circular waveguide. Results for the cut-off wave numbers of TE and TM modes are shown to be in excellent agreement with those from standard modal field-matching techniques and previously published data. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 215–225, 1998.

Analysis of ridged circular waveguides by the coupled-integral-equations technique

Cutoff wavenumbers of transverse electric (TE) and transverse magnetic (TM) modes of ridged circular waveguides are accurately determined using the coupled-integral-equations technique (CIET). A set of coupled integral equations for the electric field at the interfaces are derived and then solved by the moment method. Basis functions which include the edge conditions at all metallic edges are used. Results from this paper are compared with available data to demonstrate the accuracy and efficiency of the approach.

Mode-matching analysis of circular-ridged waveguide discontinuities

This paper describes a mode-matching algorithm for S-parameter computation of circular-ridged waveguide (CRW) discontinuities. The ridges are shaped like the cross section of a cone (pie-shaped) with a geometry that can he described in cylindrical coordinates. This idea avoids the use of a mixed-coordinate system in the analysis of the electromagnetic fields in the ridged sections, which can, therefore, be expressed in terms of modal functions. The resulting algorithm is fast and accurate and has been utilized to design and optimize a five-section double-ridge filter and a quadruple-ridge waveguide transformer. The measured response of the filter is in good agreement with the calculated data.

A Comparative Study of Two Integral-Equation Formulations of Te Modes in Circular Ridged Waveguide

We present and compare two integral-equation formulations of the TE eigenvalue problem of a ridged circular waveguide. In the E-formulation, an integral equation for the tangential electric field Eø. is derived and solved by the moment method using basis functions which include the edge conditions. The H-formulation relies on an integral equation for the axial magnetic field Hz, which is also solved by the moment method and basis functions with edge conditions. Spurious roots are encountered in the E-formulation whereas the H-Formulation is free from spurious roots but requires larger matrices. Results from both formulations are compared with previously published data and analytic results for limiting cases, excellent agreement is demonstrated.

Radial mode matching analysis of ridged circular waveguides

In this paper a radial mode matching analysis is presented to calculate rigorously the TE and TM mode propagation in single- double-, triple-, and quadruple-ridged circular waveguide structures. The ridges have been cut radially in all the cases. Results are presented for variations of the ridge depth and ridge thickness and are compared to results from finite element analysis. Furthermore, for the first time, the characteristic impedance of the double and quadruple-ridged circular waveguides have been calculated using the power-voltage definition.

Modenanalyse des Stegrundhohlleiters

A modal analysis of a ridged circular waveguide is presented. The method of Kuhn [1] is used to find suitable expressions for the vectorpotentials, wherefore the ridged waveguide is intersected into a lot of regions. With the mode-matching method an infinite set of linear equations is derived. This set of equations is truncated and the behaviour of the eigenvalues is shown.

Dual-mode circular waveguide filters without tuning screws

The manufacture of dual-mode circular waveguide filters is a complex and labor-intensive task that could be greatly simplified with the use of accurate and fast CAD tools to predict the electrical behavior of the structures being developed. This is especially true for the tuning screws assembly that is an integral part of this type of filter. A method is proposed for the rigorous and efficient analysis of the tuning screws assembly for dual-mode filters in circular waveguides. The method is based on the introduction of a new waveguide called a ridged circular waveguide and in its use as a key component for the implementation of dual-mode filters. The modal spectrum of the ridged circular waveguide is investigated using the finite-element technique to show how the introduction of this waveguide can effectively resolve the problem of the CAD of the tuning screws in dual-mode filters in circular waveguides.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>