Investigations of complex modes in a generalized bilateral finlinewith mounting grooves and finite conductor thickness

A generalized bilateral finline with mounting grooves and finite conductor thickness is analyzed by a full-wave mode-matching method. The final nonstandard eigenvalue equation is derived from the unknown coefficients in the slot regions to reduce the size of the matrix equation. The convergence studies of the mode-matching method is first studied for the fundamental mode of a symmetric bilateral finline. Both the propagation constant and the characteristic impedance as defined by the power-voltage relationship are analyzed and compared to the existing data. Excellent agreement is obtained. The effects of metallization thickness and mounting grooves are discussed. The accurate results obtained for the fundamental mode by the mode-matching method with respect to both relative and absolute convergence were also obtained for the complex modes of the finline. The dispersion characteristics of the fundamental, higher order, evanescent, and complex modes are presented for an asymmetric bilateral finline. The effects of mounting grooves and metallization thickness on the complex mode propagation constants are investigated and discussed     

Accurate Hybrid-Mode Finline Configurations Including Analysis of Various Multilayered Dielectrics, Finite Metallization Thickness, and Substrate Holding Grooves

An accurate analysis of various finline configurations is introduced. The method of field expansion into suitable eigenmodes used considers the effects of finite metallization thickness as well as waveguide wall grooves to fix the substrate. Especially for millimeter-wave range applications, the propagation constant of the fundamental mode is found to be lower than by neglecting the finite thickness of metallization. For increasing groove depth in cases of asymmetrical and "isolated finline," higher order mode excitation reduces the monomode bandwidth significantly. In contrast to hitherto known calculations, this parameter only causes negligible influence on a fundamental mode if the groove depth is lower than hall of the waveguide height.     

Explicit formulas of propagation characteristics for unilateral finline

In this paper, the unilateral fintine characteristics including finite metallization thickness and depth of mounting grooves are analysed by transverse resonance principle combining moment method. The numerical results are presented, the influence of the finite metallization thickness and depth of grooves on the propagation characteristics are investigated in detail. Finally, a set of explicit formulas for the propagation characteristics of unilateral fintine are developed. To be compared with the rigorous numerical results, the errors are within ±1% for phase constant and ±2% for characteristic impedance respectivelly.     

Finite element analysis of inductive strips in unilateral finlines

A three-dimensional finite-element method (FEM) is used in conjunction with the boundary-marching algorithm to characterize inductive strips in unilateral finlines. For an idealized finline of zero fin thickness, without mounting groove effect, the results agree with those obtained by the hybrid-mode spectral-domain approach to within a few percent with only 98 elements. Field distributions for the dominant propagation mode in unilateral finlines are generated with the boundary-marching algorithm. The effect of metallization thickness, the influence of the mounting groove, and the effect of substrate bending on the discontinuity parameters are studied in detail     

Analysis of Finline with Finite Metallization Thickness (Short Papers)

In this paper, we present a method for analyzing finline structures with finite metallization thickness. The method is based on a hybrid mode formulation but it by-passes the lengthy process of formulating the determinantal equation for the unknown propagation constant. Some numerical results are presented to show the effect of the metallization thickness for unilateral and bilateral finlines.     

Numerical modeling of generalized millimeter-wave transmission media with finite element and transmission line matrix methods

In this paper, a general finite element method as well as a graded-mesh TLM procedure for determining the dispersion characteristics, field distribution, pseudo-impedance and losses of generalized millimeter-wave transmission media are described. These methods cover arbitrary cross-sections and account for realistic features (finite metallization thickness, substrate mounting grooves etc.) that are often neglected in theoretical analysis. Dispersion characteristics and characteristic impedances obtained for dielectrically loaded ridged wave-guides compare well with the available data. Conductor and dielectric losses are also computed for these structures. A modified finline structure called “ridged finline” is also analysed. The main advantages of this structure are its large monomode bandwidth and reduced dispersion. The cutoff frequencies of bilateral finlines in circular waveguides are also computed.     

鳍线阻抗不连续性的混合模散射特性

本文用混合模展开鳍线中的本征场,并应用谱域法确定主模和高次模的传播常数和谱域中的本征场,然后结合模匹配法分析鳍线阻抗不连续性的混合模散射特性。文中给出计算的单鳍前30个模,双鳍前20个模的传播常数和阻抗不连续性的主模散射参数,计算结果与文献发表的结果一致。有关数值收敛性问题亦在文中进行了讨论。     

Analysis of the Characteristics of an Earthed Fin Line

This paper presents a theoretical and experimental investigation of the effective permittivity and the characteristic impedance of the earthed unilateral fin line. Using the Ritz-Galerkin method, the eigenvalue equation for a fin line with finite metallization thickness as well as a longitudinal slit in the metal waveguide mount is derived. The numerical solution converges very rapidly in all the cases investigated. Experimental checks are reported, which verify the results of this method and stress the importance of the effects of the finite metallization thickness and longitudinal slit in the mount at higher frequencies. The theoretical results are compared with results by Hofmann, and they are found to correspond closely.     

A D-band frequency doubler with GaAs Schottky varistor diodes

A D-band hybrid frequency doubler is developed with varistor diodes. The multiplier circuit substrate is RT/duroid 5880 with a thickness of 0.127 mm. In the circuit, the improved waveguide to unilateral finline transition is implemented with lower transition loss by cutting off high-order modes, and the reliability of the mounted circuit is enhanced with increased mounting groove depth. The D-band doubler exhibits the highest efficiency of 2% at 150.2 GHz; the typical efficiency is 1.9% from 150 to 150.5 GHz. The experimental and simulated results are in good agreement.     

Systematic Characterization of the Spectrum of Unilateral Finline

The fundamental mode of finline is well documented. A sufficiently complete knowledge of the higher mode spectrum, however, is necessary for the treatment of discontinuities. This paper is concerned with a rigorous approach to the problem of the spectrum of unilateral finline on the basis of a variational solution in the space domain and transverse equivalent network considerations. We call this method transverse resonance diffraction. Having satisfied the correct edge condition a priori, the analysis produces highly accurate dispersion characteristics calculated at each "spot frequency" for the fundamental and higher order modes with matrices of very low order. By exploiting the quasi-analytical character of the model, it is possible to derive a systematic and complete characterization of the spectrum in terms of "mode families." Moreover, simple-to-use wide-band approximations to the dispersion characteristics are also obtained which are suitable for evacuation by a desktop calculator.     

Effects of various suspended mounting schemes on modecharacteristics of coupled slotlines considering conductor thickness forwideband MIC applications

Propagation characteristics of fundamental and higher-order modes are determined in coupled slotlines with three suspended mounting schemes (pedestal, groove, inverse pedestal) for wideband applications of microwave and millimeter-wave integrated circuits. The analysis is based on a novel enhanced spectral domain approach (ESDA) that combines essentially the conventional spectral domain technique with the power conservation theorem. Numerical results, considering also the influence of finite conductor thickness, are presented for propagation constants and characteristic impedance of the fundamental modes. Effects of different suspended mounting schemes on cutoff frequencies of first higher-order even and odd modes are discussed in detail. Field profiles of the fundamental modes in coupled slotlines with and without pedestals are shown. The inherent mechanism of mode transition is explained with respect to different pedestal sizes, indicating that the monomode bandwidth can be extended by appropriately choosing the dimension of pedestal in coupled slotlines     

Coupled mode analysis of a finline

A theoretical analysis of a unilateral finline loaded with arbitrary inhomogeneous lossy dielectric material is presented. The rigorous coupled-mode approach is used. The electromagnetic field in the line is expressed in terms of the modes of a ridged waveguide, and the problem is transformed to a matrix eigenvalue equation. Approximate expressions are derived for investigating the properties of the fundamental mode in finlines loaded with dielectric slabs. Dispersion characteristics, the characteristic impedance, and the attenuation due to dielectric losses and the finite conductivity of the metal coating are computed for various line configurations. The numerical results are compared to data obtained by means of the spectral-domain method, proving the validity and usefulness of the proposed approach     

Surface Waves on Radially Inhomogeneous Cylinders

A characteristic equation and a cutoff equation are derived for higher order surface-wave modes on lossless isotropic cylinders with arbitrary radial permittivity variation. The derivation, based on the use of the fundamental matrix of a set of differential equations, reduces analytical work and results in expressions well suited for digital computer evaluation of surface-wave eigenvalues and mode spectra. The theory is applied in an investigation of HE/sub 21/ and EH/sub21/ mode propagation for a particular set of models for the radially varying permittivity. Typical results showing eigenvalue variation, dispersion characteristics and radial field variation, including experimental verification of dispersion characteristics, are shown. The method of analysis can be extended to anisotropic cylinders with permittivity a function of both radius and frequency.     

一种分析有限金属厚度和有限电导率的共面波导结构的有效方法

采用分区直线法与渐近拟合阻抗边界条件相结合的方法,对一种具有限金属厚度和有限电导率的共面波导结构的相对介电常数和损耗特性进行了分析,这是一种全波分析方法,并且可以适用于趋肤深度与金属厚度之比为任意数值的情况。计算实例证明了该方法的正确性和有效性。     

Full-wave analysis of coplanar strips considering the finite stripmetallization thickness

An extensive analysis, based on a full-wave mode-matching technique, is described for coplanar strips (CPS) incorporating the strips' finite metallization thickness. Results for the effective dielectric constant and characteristic impedance are presented to show the effect of the metallization thickness. It is found that the characteristic impedance has a strong dependence on the metallization thickness, which signifies the fact that the finite metallization thickness needs to be considered in designing practical microwave circuits employing CPS. Numerical results of CPS with zero metallization thickness obtained using this method are found to be in good agreement with those published previously. Extensive investigation of the numerical convergence of these results is also described     

Characterization of shielded coplanar type transmission linejunction discontinuities incorporating the finite metallizationthickness effect

Frequency-dependent characteristics of shielded junction discontinuities between coplanar type transmission lines, specifically coplanar waveguide (CPW) and finline, are analyzed by the mode-matching technique. The effect of finite metallization thickness is also incorporated in the analysis for the first time. Scattering parameters of finline step discontinuity are compared with existing data to confirm the accuracy of the approach. Numerical results for finline step discontinuity, shielded CPW step discontinuity and CPW-finline transition are presented     

A Unified Approach to the Analysis of a Category of H-Plane Discontinuities

Based on the mode matching method, the generalized scattering parameters including the fundamental and higher order modes (multi-modes) are obtained for the discontinuity interface of a category of waveguide H-plane discontinuities. Then by using a general port-connection order-decrease method raised by the author, the whole discontinuity including the two interfaces and the intermediate part of finite length or zero length (as is the case for very thin inductive windows or irises) can be combined into one network, and the generalized scattering parameters of this network can be obtained from which the scattering parameters of the fundamental mode can be extracted. If needed, the equivalent circuit parameters can be calculated directly from the scattering parameters. Examples are given to show the validity and versatility of this new method for dielectric filled waveguide, inductive iris and/or window, E-plane metal and/or finline insert, and even the offset E-plane finline insert, etc.. Multiple inserts, windows and irises can also be analysed.     

The influence of metallization thickness on the characteristics ofcascaded junction discontinuities of shielded coplanar type transmissionline

A full-wave analysis based on the mode-matching technique is applied to analyze cascaded junction discontinuities of coplanar-type transmission lines, coplanar waveguide (CPW) and finline. Results for a CPW-finline transition, a shielded CPW gap and a symmetric notch incorporating the finite metallization thickness effect are presented. The influence of metallization thickness on the coupling effect exhibited by cascaded junction discontinuities is also presented and discussed     

Experimental modelling of groove effect on finline transitions at Ka-Band

The mounting groove of finline circuits is always the area of research for low loss E-Plane components. The normal practice says, the groove depth should be kept λ/4 or λ/2 according to the termination at the top surface for electrical short inside the waveguide. Here we have investigated the effect experimentally at Ka-Band for short ended circuit grooves. It has been found that if the groove depth is kept λ/10, just adequate to hold the card vertical rigidly, considerable improvement has been observed in the Insertion Loss of the line. An improvement of 0.6 dB has been observed with λ/4 to λ/10 groove depth for short ended circuit for Symmetric unilateral finline.