Analysis and synthesis of tapered microstrip transmission lines

The input voltage reflection coefficient on a tapered microstrip transmission line is analyzed and a new Fourier transform pair is derived which introduces echo time and frequency as variables. Calculations of the input reflection coefficient take into account the frequency dispersion-characteristics of the effective permittivity. An efficient method is proposed for analysis and synthesis of microstrip tapers and numerical results are presented for microstrip exponential tapers and microstrip Chebyshev tapers     

A simplified analytic CAD model for linearly tapered microstrip lines including losses

Quasi-TEM propagation, appropriate for a linearly tapered microstrip line is modeled, and known microstrip impedance behavior is approximated directly. The telegraphist's equations and the resulting ABCD matrix are solved in terms of Airy functions. The theoretical model, which includes conductor and substrate losses, has been verified experimentally.     

Broadband tapered microstrip leaky-wave antenna

This study proposes a novel scheme based on the characteristics of leaky-wave antennas for the empirical design of broadband tapered microstrip leaky-wave antennas. This scheme can explain and approximately model the radiation characteristics of a linearly tapered leaky-wave microstrip antenna. A broadband feeding structure that uses the balanced and the inverted balanced microstrip lines to form a pair of broadband baluns is also presented. The measured return loss of the inverted balanced microstrip lines has a VSWR/spl les/2 from dc to 18.6 GHz and that of the back-to-back feeding structures has a VSWR/spl les/2 from 2.2 to 18.6 GHz. This feeding structure can be used to feed a broadband planar leaky-wave antenna with a fixed mainbeam that uses the tapered microstrip structure. The measured bandwidth of the antenna for a VSWR/spl les/2 exceeds 2.3:1.     

Simple formulas for microstrip lines

A modification to earlier work is presented which allows for finite strip thickness in the calculation of microstrip impedance and line wavelength. It shows a considerable improvement in accuracy and scope over some earlier work which included strip thickness, but remains simple in form. Expressions are presented which allow calculation of Z and ?g for any microstrip geometry and relative permittivity.     

Riccati matrix differential equation formulation for the analysisof nonuniform multiple coupled microstrip lines

A Riccati matrix differential equation (RMDE) is formulated for analyzing nonuniform coupled microstrip lines (NCML's) in the frequency domain. The formulation is based on a reciprocity-related definition in the theory of multiconductor transmission lines under quasi-TEM assumption. The hybrid-mode nature of modal phase velocities and strip characteristic impedances for multiconductor microstrip structure is included. The nonlinear RMDE is first transformed into a first-order linear differential matrix equation which can be efficiently solved using method of moments. A convergence study is performed to investigate the sufficient number of basis functions used in the method. The voltage-scattering parameters of a tapered microstrip and two three-line structures are presented. The frequency responses of a pair of nonuniform coupled lines are measured and compared with calculated results     

Dispersion characteristics of square pulse with finite rise time insingle, tapered, and coupled microstrip lines

The distortion of an electrical pulse, with finite risetime (quadratic-linear-quadratic transition) caused by dispersion as it propagates along a uniform microstrip, a tapered microstrip and a coupled pair of microstrips is investigated. Closed-form analysis equations for single and coupled microstrips are used to find the frequency-dependent phase velocities. Results are presented for two different taper profiles: exponential and triangular distributions. It is concluded that the optimization of the profile will provide the least pulse distortion     

Spectral-domain computation of characteristic impedances andmultiport parameters of multiple coupled microstrip lines

A numerical procedure based on the spectral-domain techniques is formulated to compute all the frequency-dependent normal-mode parameters of general multiple coupled line structures in an inhomogeneous medium. In addition to the phase and attenuation constants for all the normal modes, these parameters include the line-mode and decoupled line modal impedances and the current and equivalent voltage eigenvector matrices of the coupled system. The multiport admittance (and impedance) matrices and coupled line equivalent-circuit model parameters are evaluated in terms of these normal-mode parameters. Numerical results for these normal-mode parameters for typical asymmetric two-, three-, and four-line microstrip structures are included to demonstrate the procedure and the frequency dependence of these parameters     

Embedded microstrip interconnection lines for gigahertz digitalcircuits

Transmission line structures are needed for the high-performance interconnection lines of GHz integrated circuits (ICs) and multichip modules (MCMs), to minimize undesired electromagnetic wave phenomena and, therefore, to maximize the transmission bandwidth of the interconnection lines. In addition, correct and simple models of the interconnection lines are required for the efficient design and analysis of the circuits containing the interconnection lines. In this paper, we present electrical comparisons of three transmission line structures: conventional metal-insulator-semiconductor (MIS) and the embedded microstrip structures-embedded microstrip (EM) and inverted embedded microstrip (IEM). In addition, we propose closed-form expressions for the embedded microstrip structures EM and IEM and validate the expressions by comparing with empirical results based on S-parameter measurements and subsequent microwave network analysis. Test devices were fabricated using a 1-poly and 3-metal 0.6 μm Si process. The test devices contained the conventional MIS and the two embedded microstrip structures of different sizes. The embedded microstrip structures were shown to carry GHz digital signals with less loss and less dispersion than the conventional MIS line structures. S-parameter measurements of the test devices showed that the embedded microstrip structures could support the quasi-TEM mode propagation at frequencies above 2 GHz. On the other hand, the conventional MIS structure showed slow-wave mode propagation up to 20 GHz. More than 3-dB/mm difference of signal attenuation was observed between the embedded microstrip structures and the conventional MIS structure at 20 GHz. Finally, analytical RLCG transmission line models were developed and shown to agree well with the empirical models deduced from S-parameter measurements     

Calculation of inhomogeneous microstrip lines

The frequency-dependent transmission properties of in-homogeneous microstrip lines are calculated by means of a waveguide model and the generalised telegraphist's equations. Examples of theoretical and experimental results are presented.     

A planar-lumped model for coupled microstrip lines anddiscontinuities

A convenient model for analyzing coupled microstrip line discontinuities is presented. A planar-lumped model similar to the planar waveguide model for single microstrip lines is developed for coupled microstrip lines. Fields underneath the two strips and those fringing at the outer edge are modeled by two equivalent planar waveguides. Electric and magnetic field coupling in the gap region is modeled by a lumped network. The lumped network parameters are evaluated such that [C] and [L] matrices for the model are identical with those for coupled lines. The model is verified by comparing coupler characteristics with those obtained by the conventional coupled line analysis. Just as the planar model of a single microstrip has been used for characterizing microstrip discontinuities, the planar-lumped model developed is used for coupled line discontinuities. Examples given include coupled microstrip sections with chamfered bends located at right angles to single microstrip lines, for which the results are in good agreement with experimental values     

Crosstalk between microstrip transmission lines

Methods for prediction of crosstalk between microstrip transmission lines are reviewed and simplified for the weak-coupling case. Classical coupled transmission line theory is used for uniform lines, and potential and induced EMF methods are used for crosstalk between nonuniform lines. It is shown that the potential method is equivalent to classical coupled transmission line theory for the case of uniform lines. An experiment was performed for uniform coupled microstrip lines for frequencies from 50 MHz to 5 GHz, and good agreement between theory and measurement was obtained for both near- and far-end crosstalk     

Computer-aided design for finlines and suspended-substrate microstrip lines

The computer-aided design of finlines and suspended-substrate microstrip lines are investigated. The numerical results of this paper show good agreement with those computed by other techniques for unilateral finlines and open suspended microstrip lines. The approach of this paper may be used to the computer-aided design of many other kinds of transmission lines and circuits for millimeter wave applications.     

Accurate model for open end effect of microstrip lines

A closed form expression for the equivalent line length associated with the single microstrip open end is presented for the use in microwave CAD programs. The maximum relative error involved is less than 2.5% and its effect can be shown to be below physical tolerances.     

Full-wave analysis of aperture-coupled microstrip lines

Two methods are presented for the analysis of aperture-coupled microstrip lines. Assuming a quasi-transverse electromagnetic traveling wave incident on the feeding line, an expression for the wave on the coupled line is derived. First, the moment method is used and the current on the coupled line is represented by a traveling wave propagating away from the slot. In the second method, the reciprocity theorem is applied to the coupled line. Both the moment method and the reciprocity method make use of the exact Green functions and produce results that are in very close agreement. An equivalent circuit is derived and the S-parameters are computed. Theoretical results are verified with measurements     

Propagation characteristics of superconducting microstrip lines

The modified spectral-domain approach is applied to study the propagation characteristics of high temperature superconducting microstrip lines whose signal strip and ground plane are of arbitrary thickness. In this study, numerical results for effective dielectric constant, attenuation constant, and strip current distribution are presented to discuss the effects due to frequency, temperature, strip thickness, and substrate loss tangent. In particular, the conductor and dielectric attenuation constants of superconducting microstrip line are depicted separately to discuss the mechanism of the line losses. A comparison with published theoretical and experimental results is also included to check the accuracy of the new approach's results     

W波段反对称渐变探针过渡转换的设计

介绍了一种反对称渐变波导微带探针过渡结构,采用高频仿真软件HFSS仿真分析了这个波导微带过渡结构在W频段的特性,并对影响过渡性能的几个因素进行了敏感性分析,得出了可供工程应用参考的设计曲线。在全波导带宽内,实现了插入损耗小于0.088 dB,回波损耗大于27 dB。该结构具有宽频带、结构简单和易加工等优点,可广泛用于毫米波固态电路系统中。     

Characterization of microstrip lines near a substrate edge anddesign formulas of edge-compensated microstrip lines [MMICs]

The proximity effects of microstrip lines near a substrate's edge present a problem for effectively designing high-packing-density MMICs (monolithic microwave integrated circuits). Proximity effects of this type are analyzed using the rectangular boundary division method. It is assumed that the cross-sectional dimensions of transmission lines in the MMICs are small compared with the wavelengths to allow the use of the quasi-TEM-wave approximation. Then, the concept of edge-compensated microstrip lines to keep the characteristic impedance constant near a substrate edge is introduced to circumvent the proximity effects and to expand the interconnection flexibility of microstrip lines on MMIC substrates. The practical design parameters of edge-compensated 50-Ω microstrip lines are given in the form of numerical data and simple polynomials for CASD (computer-aided design) work with a curve-fitting procedure. Results of capacitance measurements are compared with this theory with errors of about 1% resulting     

Overview of complementary GaAs technology for high-speed VLSIcircuits

A self-aligned complementary GaAs (CGaAs) technology (developed at Motorola) for low-power, portable, digital and mixed-mode circuits is being extended to address high-speed VLSI circuit applications. The process supports full complementary, unipolar (pseudo-DCFL), source-coupled, and dynamic (domino) logic families. Though this technology is not yet mature, it is years ahead of CMOS in terms of fast gate delays at low power supply voltages. Complementary circuits operating at 0.9 V have demonstrated power-delay products of 0.01 μW/MHz/gate. Propagation delays of unipolar circuits are as low as 25 ps. Logic families can be mixed on a chip to trade power for delay. CGaAs is being evaluated for VLSI applications through the design of a PowerPC-architecture microprocessor     

Chirped delay lines in microstrip technology

In this paper, we report on a design method for chirped delay lines (CDLs) in microstrip technology. They consist in a continuously varying strip width, so that the coupling location between the quasi-TEM microstrip mode and the same but counter-propagating mode is linearly distributed in frequency. High delay×bandwidth products, over frequency ranges of several gigahertzs, can be obtained following this procedure. Experimental data confirm the design method. Real-time Fourier analysis of wideband pulses can be performed using these CDLs     

Shunt posts in microstrip transmission lines

Shunt posts in microstrip transmission lines are analyzed by employing the planar waveguide model. A multiple expansion method with greatly enhanced efficiency and accuracy has been achieved with the development of very fast algorithms for the computation of Schloemilch-type series. The method applies to perfectly conducting imperfectly conducting, and composite shunt posts. This approach is compared with the standard point matching technique for perfectly conducting posts. The two methods are found to be in excellent agreement in regions of overlapping applicability. A fairly wide range of computed data is utilized to develop the tools needed to incorporate the post into various microstrip circuit applications. As one application, a procedure is developed for using this post to obtain effective short-circuiting qualities over a broad frequency range. As a second application, the possibility of creating filtering devices is explored using both multiple metallic post structures and single dielectric posts