The influence of finite conductor thickness and conductivity onfundamental and higher-order modes in miniature hybrid MIC's (MHMIC's)and MMIC's

The effect of finite metallization thickness and finite conductivity on the propagation characteristics of conductor-backed CPW on thin substrate is rigorously analyzed. A self-consistent approach is used together with the method of lines (MoL) to determine the propagation constant, losses and field distribution of the fundamental and first two higher-order modes in coplanar waveguides (CPWs) with finite metallization thickness and lossy backmetallization. The method used is general and can be applied to miniature MHMICs and MMICs including lossy semiconductor substrate. It is shown that the onset of higher-order modes limits the usable frequency range of conductor-backed CPWs. The analysis also includes microstrip transmission lines on thin substrate material. It is demonstrated that a resistive strip embedded into the microstrip ground plane may potentially be useful in the design of integrated planar attenuators     

Transmission characteristics of suspended striplines with finite metallisation thickness and substrate supporting grooves

This letter presents an accurate hybrid-mode analysis of suspended striplines with finite metallisation thickness and substrate supporting grooves. Particular attention is paid to the calculation of the characteristic impedance. The significant effects of finite metallisation thickness and substrate supporting grooves on the transmission characteristics of suspended striplines are revealed in the higher frequency range.<>     

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     

A modified transverse resonance method for the analysis ofmultilayered, multiconductor quasiplanar structures with finiteconductor thickness and mounting grooves

A modified transverse resonance method is presented for analyzing generalized multilayered, multiconductor quasiplanar structures with practical parameters such as finite conductor thickness and mounting grooves. Recurrence relations are obtained by using network theory for obtaining the overall transverse equivalent network. while the discontinuity involving the finite-thickness metal sheet and mounting groove is carried out by a field-theory-based multimodal variational formulation. The frequency behaviors of propagating, evanescent, and complex modes are obtained for several commonly used quasiplanar lines, showing good agreement with published results. Furthermore, a leaky-wave study is carried out for open structures, since the open condition can be included in this formulation without difficulties     

Experimental evidence of mounting grooves and serration patterns on fin lines characteristics

In this paper, the mounting grooves and serration patterns of fin line circuits are investigated experimentally. Our measurements show that the short-circuit ended mounting grooves degrade seriously the insertion loss of fin lines at the low frequencies of the band. The open ended mounting grooves are found better for fin lines applications and measurements. An improvement of 0.7 dB is observed over the whole band, when the serration patterns of the fin line are placed into the open-ended mounting grooves. These results can be used for measuring the losses and for designing transitions or other fin line circuits.     

Analysis of dispersion and series gap discontinuity in shieldedsuspended striplines with substrate mounting grooves

Dispersion and series gap discontinuity of shielded suspended striplines (SSLs) on Duroid substrate (ϵ_r=2.22) are analyzed using the finite-difference time-domain method (FD-TD). Numerical accuracy of better than 0.15% is achieved when the FD-TD is used to calculate the effective dielectric constant (ϵ_reff ) of an air-filled rectangular coaxial transmission line. Data obtained for the frequency-dependent ϵ_reff of uniform SSLs and both scattering and equivalent circuit parameters of various series gap discontinuities are presented. In general, the presence of sidewall mounting grooves causes a nearly frequency-independent small reduction in ϵ_reff. On the other hand, proximity effects of the housing are found to be more important. For the gap discontinuity, coupling across the gap is stronger for wider strips and/or narrower gap width. Irregular transmission behavior is also found when the strip is wide enough to interact strongly with the sidewalls     

Fast location of high-order modes for boxed microstrip with finite strip thickness

Many analyses of boxed microstrip discontinuities require the location of large numbers of high-order modes. Using Sturm-Liouville theory, this letter derives a relationship between microstrip modes and slab-loaded guide modes, leading to an efficient mode location algorithm for microstrip, including microstrip with finite strip thickness.<>     

TE and TM modes in transmission lines with circular outer conductor and eccentric circular inner conductor

TE and TM modes in transmission lines with circular outer conductor and eccentric circular inner conductor are calculated by the help of the method of conformal transformation. Some results are presented.     

Metallization thickness in bilateral and unilateral Finlines

The theory and numerical results are presented to the effective dielectric constant and characteristic impedance of bilateral and unilateral finlines with metallization thickness. The full wave analysis of the transverse transmission line — TTL method is used to determine the electromagnetic fields of the structure in Fourier transform domain — FTD. Applying the suitable boundary conditions and the moment method, a homogeneous matrix system is obtained and the effective dielectric constant is extracted. The characteristic impedance is obtained using the relation between the voltage in slot and the transmitted power. Computational programs are developed to obtain numerical results to the effective dielectric constant and characteristic impedance.     

Experimental investigations of the influence of mounting grooves and serration patterns on the transmission characteristic of fin-lines

Using a back-to-back rectangular waveguide-fin-line transition, this paper investigates experimentally the influence of mounting grooves and serration patterns of fin-lines on the transmission characteristics. The experimental results are useful to design the rectangular waveguide-fin-line transition and other fin-line circuits.     

Real time visualization of thickness modes in crystal resonators

A technique has been developed for visualization of the longitudinal cross-section of an acoustic beam emitted by quartz resonators immersed into water. The technique is useful for studying vibration patterns of thickness modes.     

On the mode-coupling formation of complex modes in a nonreciprocalfinline

This paper studies and models the mechanism for forming the complex modes commonly found in boxed quasi-planar or planar guided-wave structures. To illustrate the fact that the mode-coupling among the various forms of modes is closely related to the formation of complex modes, the dispersion characteristics of the complex propagation constants (or the so-called mode spectrum) of a nonreciprocal unilateral finline are obtained by the rigorous full-wave SDA (spectral-domain approach). It is found that in the mode spectrum of the nonreciprocal finline, a forward wave and a backward wave interact to produce a pair of complex modes. The interactions between two forward (backward) traveling waves, between a forward wave and a backward wave, and between two complex waves (modes) are modeled by applying the mode-coupling theory. The concept of hypothetical modes is introduced in the model. These hypothetical modes are obtained by applying mode-coupling theory to the mode spectrum previously obtained. The approximate values obtained for the propagation constants of the three types of wave interactions using the model presented in the paper are in close agreement with those given by the full-wave SDA     

Simple and accurate formulas for a microstrip with finite strip thickness

Simple and accurate dosed form expressions for variation of characteristic impedance and effective dielectric constant of microstrip with finite strip thickness are reported. The results are in good agreement with the numerical values. These expressions are useful for microstrips used in microwave integrated circuits and computers.     

Dispersion study of open slot-lines taking into account conductor thickness and substrate width

By means of singular integral equations' method we've studied dispersion of open slot lines having nonstandard cross-section geometry. Peculiar dependence of eigenmodes' number and slot width between conductor strips has been found.     

Accurate determination of modes in dielectric-loaded cylindricalcavities using a one-dimensional finite element method

A unified approach is presented for calculating the resonant frequencies of all the modes in cylindrical cavities axisymmetrically loaded with dielectrics. In this method, the radial variations of the field components in the resonator are expressed in terms of first-degree finite-element polynomials, whereas the axial variations of the field components are approximated by trigonometric functions. To calculate the resonant frequencies, an H-vector variational formulation is employed and minimized with respect to the coefficients of the expanded field components. Spurious solutions which are inherent in the finite-element technique are effectively eliminated by means of a penalty term included in the variational expression, imposing a divergence-free magnetic field constraint. To show the capability of the method, resonant frequencies of several cylindrical cavities, including those loaded with dielectric rods and dielectric rings, were calculated. A mode chart is presented which can be used for designing certain multimode dielectric-loaded cavity filters. In contrast to other rigorous techniques reported in the literature, the present method is highly efficient when dielectrics are fully extended along the cavity length     

Natural frequencies and modes of finite open circular cylinders

The natural frequencies and natural modes of open circular cylinders of given aspect ratios are calculated by means of a Galerkin procedure involving entire domain bases. The results are validated by comparison with other calculations of natural frequencies and modes for cylinders and time response current for wires. The usefulness of a previously proposed method based on perturbation theory is examined in this context.     

Rigorous dispersive analysis of skin effects on a printed microstrip line containing finite conductor losses

Theoretical full-wave analyses of skin effects on a microstrip line plated with 1 mil (1/1000 inch) thick gold conductor are presented. The time-harmonic complex longitudinal and transverse current distributions inside and on the surface of the metal strip are reported for a microstrip operating at 100 GHz. The case study shows that the current distributions obtained by the new full-wave approach agree well with those predicted by the well-known plane analysis of skin effects.<>     

The complex resistivity response of a homogeneous Earth with afinite-length contained vertical conductor

The complex resistivity response of a homogeneous Earth with a finite-length contained vertical conductor such as an oil well casing is considered. The calculational procedure developed is the equivalent of the so-called quasi-static approximation and includes a consideration of longitudinal conductor impedance and dipole-dipole array mutual coupling. The validity of the procedure is confirmed by showing that the results for long cylinder lengths are in excellent agreement with analytical calculations for infinite length cylinders available in the literature. Calculated curves of the apparent complex resistivity as a function of frequency and cylinder length for a typical field measurement are presented to indicate the effect of oil well casings on induced polarization surveys     

Capacitance of a circular symmetric model of a via hole including finite ground plane thickness

The capacitance of a simplified model of a via hole is calculated based on an integral equation approach for the surface charge density. The formulation of the problem is based on an integral equation for the surface charges combined with an analytical solution at the ground plane opening. The finite ground plane thickness is explicitly taken into account. Numerical data are obtained for a large range of realistic geometrical data. The relative importance of the contribution to the total capacitance coming from the ground plane opening is explicitly evaluated. It is found that the via capacitance is proportional to the square root of its height, at least for the range of geometrical data considered.<>     

Frequency estimation of a single complex sinusoid using a generalized Kay estimator

This letter introduces a generalized version of Kay's estimator for the frequency of a single complex sinusoid in complex additive white Gaussian noise. The Kay estimator is a maximum-likelihood (ML) estimator at high signal-to-noise ratio (SNR) based on differential phase measurements with a delay of one symbol interval. In this letter, the corresponding ML estimator with an arbitrary delay in the differential phase measurements is derived. The proposed estimator reduces the variance at low SNR, compared with Kay's original estimator. For certain delay values, explicit expressions for the window function and the corresponding high SNR variance of the proposed generalized Kay (GK) estimator are presented. Furthermore, for some delay values, the window function is nearly uniform and the implementation complexity is reduced, compared with the original Kay estimator. For a delay value of two, we show that the variance at asymptotically high SNR approaches the Cramer-Rao bound as the sequence length tends to infinity. We also explore the effect of exchanging the order of summation and phase extraction for reduced-complexity reasons. The resulting generalized weighted linear predictor estimator and the GK estimator are compared with both autocorrelation-based and periodogram-based estimators in terms of computational complexity, estimation range, and performance at both low and high SNRs.