Showing papers on "Microstrip published in 1980"

Accurate Models for Microstrip Computer-Aided Design

Abstract: Very accurate and simple equations are presented for both single and coupled microstrip lines' electrical parameters, i.e. impedances, effective dielectric constants, and attenuation including the effect of anisotropy in the substrate. For the single microstrip the effects of dispersion and non-zero strip thickness are also included.

Spectral Domain Immitance Approach for Dispersion Characteristics of Generalized Printed Transmission Lines

Abstract: A simple method for formulating the dyadic Green's functions in the spectral domain is presented for generalized printed transmission Iines which contain several dielectric layers and conductors appearing at several dielectric interfaces. The method is based on the transverse equivalent transmission line for a spectral wave and on a simple coordinate transformation. This formulation process is so simple that often it is accomplished almost by inspection of the physical cross-sectional structure of the transmission line. The method is applied to a new versatile transmission line, a microstrip-slot Iine, and some numerical results are presented.

Improved bandwidth of microstrip antennas using parasitic elements

Abstract: A method is described of doubling the bandwidth of rectangular microstrip patch antennas by locating capacitively excited λ m /4 short circuit parasitic elements at their radiating edges. The antenna characteristics are explained in terms of an antiphase mode of a pair of coupled resonators, and it is shown that the bandwidth improvement is independent of the coupling capacitance. Experimental results are presented for both linearly and circularly polarised antennas which support the theoretical predictions.

Effects of Fringing Fields on the Capacitance of Circular Microstrip Disk

Abstract: The effects of fringing fields on the capacitance of a circular microstrip disk are studied with the dual integral equation formalism for practical microstrip circuits when the substrate thickness is small. Approximations as well as exact numerical evaluations are made in the calculation of the capacitance. With a seminumerical approach, an approximate formula for the capacitance is obtained and shown to yield accurate results with the simple use of a calculator. Asymptotic lower bound and exact numerical computations are also carried out. The various techniques are illustred and compared with numerical results.

Design Considerations in Microstrip Antenna Fabrication

Abstract: Deviations in effective electrical dimensions caused by slight variations in finished microstrip antenna length, variations in the relative permittivity of the substrate material or nonuniformity in the substrate thickness lead to discrepancies between the designed and actual resonant frequencies. This sort of discrepancy is especially significant because of the narrow bandwidth of such antennas. It is found that for low dielectric substrate microstrip antennas, the critical parameter affecting the change in resonant frequency is the error in antenna length while for high permittivity substrates, the tolerance in dielectric constant is the critical parameter.

Analysis of a Microstrip Covered with a Lossy Dielectric

Abstract: The analysis of a microstrip line covered with a low-loss sheet material is presented in this paper. Numerical results show that the characteristics of a microstrip covered with a thick sheet of high dielectric constant are drastically affected. The effect is more for small values of W/h ratio. A closed-form expression for the dielectric loss of a multilayer structure is derived.The extension of present method to high-loss materials is also discussed. Numerical and experimental results for effective dielectric constant of a microstrip covered with low- and high-loss sheet materials are compared and found to be in good agreement.

Losses of Microstrip Lines

Abstract: This article summarizes state-of-the-art information on losses of single and coupled microstrip lines. Conductor loss, substrate loss (for pure dielectric or magnetic materials), and radiation loss are considered along with the effect of dispersion. Finally, a rough comparison is made between the losses of microstrip and that of several other types of lines used in microwave integrated circuits.

A New Microstrip Radiator For Medical Applications

Abstract: Ring-type microstrip antennas appear to offer important advantages in medical therapy when used for local tissue heating. In designing these radiators, the properties of a microstrip covered with layers of lossy dielectric representing various tissue layers have to be taken into account. This paper provides basic information on design of ring-type radiators for tissue heating and the experimental results for a unit designed to operate in the TM modes at 2.45 GHz. The radiator is well matched when spaced 1.3-3 mm from muscle tissue or muscle tissue covered by a thin layer of fat tissue. A limited volume of muscle tissue is heated at a greater rate than the fat layer as shown by a thermographic technique.

Resonance of nonaxial symmetric modes in circular microstrip disk antenna

Abstract: Resonant frequencies of the nonaxial symmetric modes in a microstrip disk are computed using two approaches: Galerkin’s method and a perturbative approach. The perturbative approach is good when the substrate of the microstrip disk is thin compared to its radius and when the dielectric constant of the substrate is high. Galerkin’s method can be used to compute the resonant frequency to high accuracy but the perturbative approach is more efficient for thin substrate and large dielectric constant. In applying Galerkin’s method, the problem is first cast into a vector dual integral equation using vector Hankel transform (VHT). Using VHT, it is also shown that the magnetic‐wall model is only good when the substrate is of zero thickness. Using zero‐order current distribution on the disk, we also derive the radiation field and radiation pattern. Also, by taking into account the radiation loss, the resonant frequencies are complex. We find discrepancies when we compare our results for the resonant frequency shifts with that obtained by quasistatic approach.

A New MIC Magic-T Using Coupled Slot Lines

Abstract: Novel microwave integrated circuit (MIC) 180/spl deg/ hybrids (magic-T's) suitable for MIC are described. They make use of the two orthogonal modes (even and odd) of the coupled slot lines, and, therefore, have special port location, which is quite different from that of the conventional 180/spl deg/ hybrids such as a rat-race. That is, the two-ports, which correspond to the E-arm and the H-arm of the well-known waveguide magic-T, can be located on the same side, opposite to the other two ports. This feature is of a great practical advantage when applied to an MIC, because the crossing of the transmission lines can be omitted when this type of magic-T is applied to balanced-type circuits such as balanced mixers. Satisfactory experimental results at a center frecuency of 6 GHz are given. The isolation between the E- and the H-ports is better than 30 dB over an octave band, and the frequency sensitivity of the coupling is almost flat in the frequency range from 2 to 10 GHz.

Radio frequency energy launcher

Abstract: A radio frequency energy launcher providing efficient energy transfer between a coaxial transmission line having spaced inner and outer conductors and a microstrip transmission line comprising a first relatively thin strip conductor and second wider ground plane conductor separated by a dielectric substrate. The launcher includes a conductive housing providing a passageway forming an outer conductor and a spaced inner conductor angled with respect to the passageway outer conductor forming wall and a surface of the substrate. Such angled inner conductor having an end region connected to the coaxial transmission line and having the other end interconnected to the thin strip conductor of the microstrip transmission line. The inner conductor is angled acutely and/or obliquely to such housing wall and a surface of dielectric substrate. The launcher structure is mounted on an extension of the wider ground plane conductor of the microstrip transmission line thus permitting the utilization of a substantially thinner ground plane conductor member while assuring firm mechanical contact with the thin strip conductor microstrip transmission line. The angularly orientated launcher provides for maintaining constant impedance in the transformation of electromagnetic energy fields from a concentric coaxial line distribution to a concentrated eccentric configuration for microstrip line transmission.

A New Technique for the Analysis of the Dispersion Characteristics of Planar Waveguides Demonstrated for the Coplanar Line

Abstract: An efficient method for calculating the dispersion characteristics of planar waveguide structures is presented, of which the principle is known as the 'method of lines' in mathematical literature. The wave equation is discretized only in one direction, and the resulting differential-difference equation can be solved analytically. As an example of application and as a test for the computed results a coplanar line is calculated. The obtained results show good agreement with other available data.

Microstrip Transmission Line with Finite-Width Dielectric

Abstract: The results of a numerical solution for open microstrip transmission line with finite-width dielectric are presented for a quasi-TEM computational model. The related solution is based on moment methods using equivalent source models for the free and bound charges existing on boundary surfaces. Characteristic impedance and velocity of propagation are presented in graphical form for estimating the effects of dieletric truncation on microstrip circuits and for related circuit design.

Narrow-Band Stripline or Microstrip Filters with Transmission Zeros at Real and Imaginary Frequencies

Abstract: Simple approximate design equations are derived in this paper for an even degree (n /spl ges/ 6) low-pass inverter capacitance prototype filter having single transmission zeros at both real and imaginary frecuencies. This is achieved by utilizing one or two additional couplings. The transmission zeros improve considerably the passband group delay and increase the skirt selectivity compared to those of the ordinary Chebyshev prototype. An exact and more complicated method based on the known generalized Chebyshev rational function approximation is also presented for the comparison. The prototype with one additional coupling is utilized to realize narrow-bandpass printed circuit filters consisting of half-wave resonators.

Resonance of the axial-symmetric modes in microstrip disk resonators

Abstract: Three methods have been used to calculate the resonant frequencies for the axial‐symmetric modes in the microstrip disk resonators which also have the application as radiating antennas. The variational Galerkin’s method provides the most accurate result for the estimation of both the real and imaginary parts of the resonant frequency shifts with judicious choices of basis functions. The iterative approach gives good results for the imaginary part of the frequency shift and very crude approximations for the real part. The perturbation formula is the most efficient in computational time and is useful for sufficiently large permittivity for the substrate material and small ratio of substrate thickness to disk radius. To illustrate the application of the circular microstrip disk as a radiating antenna, the radiation pattern for the axial‐symmetric mode is also plotted.

Planar microwave integrated circuit power combiner

Abstract: A broadband, low loss, microwave integrated circuit power combiner for field effect transistors and other solid state amplifiers has a single metallized MIC substrate contained within a waveguide structure. An array of fin-line transitions from plural microstrip lines to a standard output waveguide can be tapered and placed directly in the waveguide taper region. Undesired higher order modes are absorbed by resistance metallization strips at the tips of the fin-lines or by resistor networks which bridge the microstrip lines.

Circular ring microstrip antenna elements

Abstract: The frequency characteristics of circular ring microstrip antennas were obtained as a function of relative aperture radius. In all cases the resonant frequency was normalized to that of an ideal disk microstrip antenna with the same radius, and assumed magne tic wall boundary conditions. Since, at this time, an exact value for the complex wall admittance is not known, an equivalent admittance was derived for each of several commonly used models. This admittance was then used as the boundary condition for the computation of the resonant frequency as a function of relative aperture radius. Results of these calculations are shown; also shown is the comparison with experiment.

Method for Equalizing Phase Velocities of Coupled Microstrip Lines by Using Anisotropic Substrate

Abstract: We present a method for equalizing the even- and odd-mode phase velocities of coupled microstrip lines with zero-thickness strips by using the anisotropic material cut in the appropriate direction as the substrate.

New wideband microstrip antenna using log-periodic technique

Abstract: A novel wideband microstrip antenna using a series-fed linear array of patch resonators in a log-periodic arrangement is described. A 9-element example gives good input v.s.w.r. and radiation control over a 30% bandwidth with better than 70% efficiency. The new array configuration gives wider bandwidth than single-layer or stacked microstrip patches combined with better efficiency than patches on lossy substrates or microstrip spirals.

Electric Probe Measurements on Microstrip

Abstract: The aim of the experimental investigation reported here is to measure the electric field of microstrip using a field probe. To establish the accuracy of these measurements, the probe is first calibrated against a known field which is obtained by analyzing a wire suspended axially in a rectangular metal tube. Measurements on a simple wire over ground plane circuit indicate that unshielded structures are basically unsuitable for accurate probe calibration. Finally, the theoretical results predicted by a numerical analysis program for microstrip, published recently, are verified by comparing these with the actual field distribution determined experimentally.

Finite boundary corrections to coplanar stripline analysis

Abstract: Analytic closed-form expressions for impedance and effective dielectric constant for coplanar striplines (c.p.s.) with finite substrate thickness are obtained using conformal mapping techniques. The limit, beyond which the results of an infinite dielectric approximation are no longer valid, is presented.

Design Equations for Symmetric Microstrip DC Blocks

Abstract: The design formulas are presented for achieving either a rippled or a maximally flat response of the dc blocks built with symmetrical coupled microstrip lines. The selection of characteristic impedances of the odd and even modes is facilitated by the use of a universal diagram containing the equicontours of the standing wave ratio and of the band-width. The deformation of the frequency response due to a difference in wavelengths of the odd and even modes is analyzed and the design procedure is adjusted accordingly.

A Broad-Band Element for Microstrip Bias or Tuning Circuits (Short Papers)

Abstract: A microstrip radial transmission line circuit element namely a 180/spl deg/ circular stub or "half-moon" structure, having a reflection coefficient of unity magnitude and phase which varies slowly with frequency is presented. Theoretical reflection coefficient data are shown to agree well with experimental microstrip (epsilon/sub r/=2.35, h =250 mu m) data in X band. Applications of the half-moon microstrip element in the design of broad-band bias or tuning networks are discussed.

Characteristics of Inhomogeneous Broadside-Coupled Striplines

Abstract: 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.

K-Band Integrated Double-Balanced Mixer

Abstract: A novel microwave integrated circuit (MIC) double-balanced mixer with good isolation between the three ports is described. The mixer is fabricated using a combination of microstrip lines, slotlines, and coupled slotlines, together with four beam-lead Schottky-barrier diodes. The K-band magic-T has been developed for the double-balanced mixer. The minimum conversion loss measured at a signal frecuency of 19.6 GHz is 4.7 dB. Isolation between RF and LO ports is greater than 20 dB from 18 to 21 GHz. The mixer can be expected to have wide applications in MIC receivers and transmitters up to the millimeter-wave band.

A broadband microwave signal to noise enhancer

Abstract: A signal to noise enhancer exhibits a high attenuation to small noise level signals and a lower attenuation to larger above threshold signals. The devices described rely on magnetostatic waves as saturable absorbers of power from a microwave transmission line, typically microstrip. Experiments performed with epitaxial YIG show that instantaneous bandwidths of 900 MHz with threshold levels of less than 0 dBm can be obtained below 4.2 GHz. Enhancement of greater than 20 dB can be achieved for an increase in power level of 20 dB above threshold. Characteristics obtained with lithium ferrite in the 4-8 GHz band are comparable to those obtained with YIG in the 2-4 GHz range. Owing to the increased fmr and spin wave linewidth of the lithium ferrite, the threshold level is higher, + 6 dBm, and the frequency selectivity poorer than observed with YIG.

Calculation of Quasi-Static Characteristics of Microstrip on Anisotropic Substrate Using Mapping Method

Abstract: In this paper a mapping transforms a original microstrip line on anisotropic substrate into another on isotropic dielectric. This method is applied to compute the quasi-static impedance of single microstrip on an anisotropic sapphire substrate.

Closed-Form Expressions for the Current or Charge Distribution on Parallel Strips or Microstrip

Abstract: Simple but accurate closed-form expressions for the charge and current distributions on parallel-plate stripline or microstrip are given. This form is convenient for use in various applications, such as determining radiation or mode fields of the lines, or frequency dispersion of the fundamental mode of the microstrip. These expressions are used to obtain explicit expressions for the capactitance of these lines, accurate to within one percent of the actual value for any ratio of stripwidth to spacing.

New microstrip slot radiator for medical applications

Abstract: A microstrip slot radiator for local heating of biological tissue operating at 2.45 GHz was designed and tested. The radiator is well matched within a relatively wide range of frequencies (v.s.w.r. < 1.5 for 2.45 ± 0.3 GHz) and provides energy deposition within an area of about 1.5 cm × 1 cm.