Suspended Microstrip Line Research Articles

Accurate quasi-tem analysis of modified coupled suspended microstriplines and its application to directional coupler design

In this article an efficient and accurate quasi-TEM analysis of a pair of boxed coupled microstrips with slotted ground plane is carried out. The properties of directional couplers based on this structure are theoretically studied. A synthesis program has also been developed, and an example of graphic design charts is provided for a low permittivity substrate.

Theory and design of wideband 3‐dB suspended microstrip couplers with floating conductor

AbstractUsing the spectral domain method, theoretical analysis of the characteristics of coupled suspended microstrip lines with floating conductor is presented in detail. The distributions of electrical charges on the coupled microstrip lines and floating conductor are studied, and a set of basis functions used in the calculation is obtained. Detailed numerical results and design curves are presented, and an experimental wideband 2.5‐dB coupler is designed and measured. The test results are in agreement with theoretical values. This type of coupler is simple in construction and capable of realizing tight coupling (3 dB or higher) in microwave integrated circuits (MIC) with high directivity.

Propagation characteristic for a suspended substrate microstrip line with pedestal

In the letter the full-wave analysis of a suspended substrate microstrip line with pedestal is investigated for the first time. Two auxiliary problems are constructed for obtaining the fields above and below the plane of the pedestal support. The characteristic equation is derived using the spectral Galerkin method.

Computer-aided design models for broadside-coupled striplines and millimeter-wave suspended substrate microstrip lines

Models were derived from the results of conformal transformation on homogeneous stripline, the equivalence of the odd-mode with the quasi-TEM mode of covered microstrip line, and logarithmic regression of spectral-domain results. Effects of finite strip thickness have been taken into account. These models are fully compatible with the needs and trends of computer-aided and programmable-calculator-aided microwave and millimeter-wave integrated circuit design.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

New Quasi-Static Models for the Computer-Aided Design of Suspended and Inverted Microstrip Lines (Short Paper)

New quasi-static models for the computer-aided design (CAD) and analysis of open suspended and inverted microstrip lines are reported. The models are obtained through generalizing those reported earlier and are applicable up to epsilon/sub r/= 20, thereby covering all the practically used substrate materials for these structures. The models also cover a larger range of dimension ratios and are accurate to within 0.6 percent for analysis and within 1 percent for synthesis.

Closed form expressions for the computer-aided design of suspended microstrip circuits for millimeter wave applications

In the paper, a combination of a dividing-the-capacitance approach and a curvefitting technique is used to derive closed form expressions for the characteristics of suspended microstrip line with zero strip thickness. These expressions are mainly used for the computeraided design of suspended microstrip circuits for millimetre-wave applications. Calculated results using the derived expressions are found to be in very good agreement with available numerical results. The range of validity of the derived expressions is also included.

New accurate design data for a suspended microstrip line

New design data for an open suspended microstripline is reported. Two most commonly used substrate materials, namely RT-Duroid (ɛr=2.22) and fused quartz (ɛr=3.78) are considered. Effects of dispersion and strip thickness are included in the results which are based on a fullwave spectral-domain analysis. The data, which is computed over the complete practical ranges of frequency and parameter values, is much more reliable than the currently available quasistatic results.

Effects of manufacturing tolerances on the electrical performance of suspended and inverted microstrip lines

Effects of manufacturing tolerances in the dimensions and parameters of suspended and inverted microstrip lines on the electrical performance of these lines have been studied through sensitivity analysis. The closed-form expressions recently given by Pramanick and Bhartia for the analysis of these lines have been used to derive the mathematical expressions for various sensitivities and the dependence of sensitivities on the aspect ratios and on the substrate dielectric constant has been depicted graphically. Generally speaking, the effects of tolerances are seen to be reflected much more sharply in the sensitivities of the characteristic impedance than in those of the effective dielectric constant. Many other useful inferences are also drawn from the sensitivity graphs. The conclusions are presented in tabular form, so as to be of direct help to the user.

New approach to analyse strip-and microstrip-like transmission lines with anisotropic substrates having a tilted optical axis

Generalised expressions are evolved for the line capacitance of single as well as edge-coupled strip and microstrip-like transmission lines with anisotropic substrates having a tilted optical axis. An example of a two-layered strip line with anisotropic dielectrics having a tilted optical axis is first analysed using the spectral-domain method under a quasistatic approximation. The only parameter that is dependent on the transmission line media in the expression for the capacitance is identified as the admittance at the charge plane of the structure. Since the admittance parameter for any multilayer structure can be easily and independently determined using a two-wire transmission line equivalent, the capacitance expression serves as a general formula. Numerical results on the isolated strip line and the coupled microstrip lines compare well with those reported in the literature. Computed impedance and effective dielectric constant characteristics of single and coupled inverted and suspended microstrip lines are presented as a function of the tilt angle of the optical axis of the anisotropic substrate.

Design Data on Inverted and Suspended Microstrip Lines for Mic Applications

A brief outline of the theoretical method for computing the characteristic impedance of the inverted microstrip and suspended microstrip lines, for Microwave integrated Circuit application, at frequencies above X-band, is reported in this paper. Design data on the impedance characteristics of single and coupled lines for both these configurations are presented.

Unified Approach to Solve a Class of Strip and Microstrip-Like Transmission Lines

This paper presents a unified analytical approach to solve a class of shielded strip and shielded microstrip-like transmission lines with multilayer dielectrics under TEM-wave approximation. The analysis makes use of the variational technique in the space domain combined with the transverse transmission method. Expressions are derived for the capacitance of a single line, coupled two-line and coupled four-line structures. The same formulas can be used for a class of such structures by the substitution of a single parameter, namely, the admittance at the charge plane, which can be obtained using the standard transmission line formulas. Numerical results of two special structures, namely, the broadside-coupled suspended microstrip lines, and broadside-coupled inverted microstrip lines, using two suspended, dielectric substrates are included. The technique presented is the simplest compared to any other analytical procedures reported in the literature.

Propagation Parameters of Coupled Microstrip-Like Transmission Lines for Millimeter-Wave Applications

A variational expression is derived for the propagation parameters of coupled microstrip-like transmission lines for millimeter-wave applications using the transverse transmission line method. Numerical results are presented for the coupled inverted microstrip lines, and for the coupled suspended microstrip lines. The effects of the top and sidewalls and also of the finite thickness of strip conductors on the even- and odd-mode impedances are studied. The use of a dielectric overlay in equalizing the even- and odd-mode phase velocities is investigated.

Method for improving microstrip coupler directivity

This letter describes a method for improving the directivity of the edge-coupled microstrip couplers; the coupler is made up of the suspended microstrip lines. The gap between the dielectric substrate and the ground plane is adjusted to get equal mode velocities under perfect matching conditions. Design data for optimum structure and experimental results are presented and discussed.

Characteristics of Inhomogeneous Broadside-Coupled Striplines

A variational method for the analysis of inhomogeneous broadside-coupled striplines is described. The data for even- and odd-mode characteristic impedances, effective dielectric constants, and mode phase velocity ratios are presented. It is found that the phase velocity ratio may be varied over the range 1.14 /spl les/ ( V/sub e/ / V/sub 0/) /spl les/ 3.6 for broadside-coupled suspended microstrip lines (BSML) and 0.36 /spl les/ ( V/sub e/ / V/sub 0/) /spl les/ 0.93 for broadside-coupled inverted microstrip lines (BIML) using materials with dielectric constant less than 16 and S/b /spl ges/ 0.05, W/b /spl les/ 2.0. The effect of nonzero strip thickness is also calculated. It is noticed that the effect of thickness is more pronounced for the odd-mode case than for the even mode. Losses are obtained using the incremental inductance rule of Wheeler. The odd-mode attenuation constant is always higher than the even-mode value.

Frequency-dependent solution of suspended microstrip line with tuning septums

The frequency-dependent effective dielectric permittivity and equivalent characteristic impedances of the technically most relevant modes of the suspended microstrip line with tuning septums are derived using the conventional spectral domain approach. Normalised numerical results are presented in a very large frequency band.

Generalized Spectral Domain Method for Multiconductor Printed Lines and its Application to Turnable Suspended Microstrips

An efficient method is developed for obtaining propagation characteristics of microstripline type structures in which a number of conductors are located on various interfaces. Specific computations have been carried out for suspended microstripline structures with tuning conductive septums. A number of data useful for design are included.

A Generalized Spectral Domain Analysis for Coupled Suspended Microstriplines with Tuning Septums

An efficient computation method is developed for solving the microstrip-type structures in which a number of conducting strips are located on several interfaces of dielectric layers. The method is applied to the coupled suspended microstripline with tuning septums on the underside of the suspending dielectric layer. The numerical solutions obtained by the new method are compared with available data. The method is believed useful in the design of tightly coupled structures such as the 3-dB hybrid as well as of transitions between different transmission lines for microwave and millimeter-wave integrated circuit application.