Showing papers on "Microstrip published in 1969"

Coplanar Waveguide, a Surface Strip Transmission Line Suitable for Nonreciprocal Gyromagnetic Device Applications

Abstract: A coplanar waveguide consists of a strip of thin metallic film on the surface of a dielectric slab with two ground electrodes running adjacent and parallel to the strip. This novel transmission line readily lends itself to nonreciprocal magnetic device applications because of the built-in circularly polarized magnetic vector at the air-dielectric boundary between the conductors. Practical applications of the coplanar waveguide have been experimentally demonstrated by measurements on resonant isolators and differential phase shifters fabricated on low-loss dielectric substrates with high dielectric constants. Calculations have been made for the characteristic impedance, phase velocity, and ripper bound of attenuation of a transmission line whose electrodes are all on one side of a dielectric substrate. These calculations are in good agreement with preliminary experimental results. The coplanar configuration of the transmission system not only permits easy shunt connection of external elements in hybrid integrated circuits, but also adapts well to the fabrication of monolithic integrated systems. Low-loss dielectric substrates with high dielectric constants may be employed to reduce the longitudinal dimension of the integrated circuits because the characteristic impedance of the coplanar waveguide is relatively independent of the substrate thickness; this may be of vital importance for Iow-frequency integrated microwave systems.

Microstrip lines for microwave integrated circuits

Abstract: Microstrips, transmission lines of metallic layers deposited on a dielectric substrate, are very useful for the microwave and millimeter wave hybrid integrated circuits required for solid-state radio systems because of their simplicity and planar structure. To design hybrid integrated circuits with microstrips requires computation or measurement of the impedance, the attenuation, the guide wavelength, and the unloaded Q of the line. These parameters can be obtained from the effective dielectric constant and the characteristic impedance of the corresponding air line. This paper gives the exact design data for all line parameters for the most important cases. We report the impedance and attenuation measurements performed on microstrips. Satisfactory agreement is obtained with theoretical results based on conformal mapping with logarithmic derivatives of theta functions and expressions involving the partial derivatives of the impedance with respect to independent line parameters.

Slot Line on a Dielectric Substrate

Abstract: Slot line consists of a narrow gap in a conductive coating on one side of a dielectric substrate, the other side of the substrate being bare. If the substrate's permittivity is sufficiently high, such as /spl epsiv//sub r/ = 10 to 30, the slot-mode wavelength will be much smaller than free-space wavelength, and the fields will be closely confined near the slot. Possible applications of slot line to filters, couplers, ferrite devices, and circuits containing semiconductor elements are discussed. Slot line can be used either alone or with microstrip line on the opposite side of the substrate. A "second-order" analysis yields formulas for slot-line wavelength, phase velocity, group velocity, characteristic impedance, and effect of adjacent electric and magnetic walls.

Interdigitated Stripline Quadrature Hybrid (Correspondence)

Abstract: lnterdigitated microstrip couplers consist of three or more parallel striplines with alternate lines tied together. A single ground plane, a single dielectric, and a single layer of metallization are used. Thus the approach is eminently suited for monolithic or hybrid thin-film microwave integrated circuitry. Tight coupling is achieved much more easily than with noninterdigitated edge-coupled lines. Fabrication and tolerance problems make it almost impossible to build noninterdigitated 3-dB edge couplers. Also, current crowding at the edges, which can result in high loss, is much less severe for the interdigitated coupler. Previously, tight coupling in directional couplers for microwave integrated circuits has been achieved by broadside coupling, reentrant sections, tandem sections, or branch-line couplers. Some of the disadvantages of these approaches are narrow bandwidth, large substrate area, and the need for multilayer circuitry. A 3dB directional coupler (quadrature hybrid) for S band has been fabricated in microstrip on 40-mil alumina. A single quarter-wave section was used. The hybrid showed a directivity of over 27 dB, a return loss of over 25 dB, an insertion loss of less than 0.13 dB, and an imbalance of less than 0.25 dB over a 40 percent bandwidth.

Coupled Transmission Line Networks in an Inhomogeneous Dielectric Medium

Abstract: In this paper, two-port networks composed of two identical, coupled transmission lines embedded in an inhomogeneous dielectric (e.g., suspended substrate, microstrip) are investigated. The ABCD parameters of circuit configurations, considered by Jones and Bolljahn, are obtained for the case of inhomogeneous dielectilc. Equivalent circuits of these networks are also given. It is shown that the characteristics of such circuits differ markedly from those embedded in a homogeneous medium. In addition, experimental results are presented for three types of circuits which have been constructed and tested. There is excellent agreement between the experimental results and those predicted theoretically on the basis of the equivalent circuits.

Measurement techniques in microstrip

Abstract: A novel technique has been developed for measurement of dispersion and wavelength in microstrip transmission line laid down on an Al2O3 substrate. The frequency range so far investigated has been 4-12GHz, although the method could be satisfactorily used at far higher frequencies. The measurement accuracy is better than within 1%. Techniques for producing well matched transitions to any thickness substrate have also been established.

Circular resonant structures in microstrip

Abstract: Mode patterns of circular disc resonant sections are analysed. Radiation losses are expected to be small for the dominant mode, which would therefore have the highest Q value.

Slot Line Characteristics

Abstract: The slot line, a novel transmission line suitable for application to microwave integrated circuits, may be used in place of or in association with microstrip. This paper presents experimental and theoretical data concerning slot line wavelength, characteristic impedance, transitions, and tolerances. The measurements have been conducted at S band using different dielectric constant materials. Experimental results indicate that the slot wavelength /spl lambda/ agrees with theory to within 2 percent, whereas the characteristic impedance of the slot line was measured to be about 30 percent less than the theoretical value. Tolerances associated with the theoretical slot line parameters were not found to be critical.

Dielectric loss in integrated microwave circuits

Abstract: Dielectric loss is important in integrated microwave and millimeter wave circuits which require small attenuation. Such circuits are usually built with microstrip or suspended microstrip transmission lines. This paper shows that the dielectric loss, the filling factor of the microstrip, and the stored field energy in the dielectric substrate can be computed from the partial derivative ∂U/∂∊ r where U is the total electric field energy and ∊ r the relative dielectric constant of the substrate. It also shows that the effective loss tangent is determined by the partial derivative ∂∊ eff /∂∊ r where ∊ eff is the effective dielectric constant of the microstrip. Useful design formulas for computing the dielectric loss are given for the most important cases.

The Even and Odd Mode Capacitance Parameters for Coupled Lines in Suspended Substrate

Abstract: This paper describes the calculation of fringing capacitances in the suspended substrate transmission medium. In this medium, conductors are photoetched on one side of a dielectric card supported approximately halfway between two parallel ground planes. Usually a large number of thin film circuits are supported on a single card and are therefore coupled. The parameters needed to characterize coupled microwave structures are the surge impedances and phase velocities of the normal modes. For lumped circuits, or combinations of lumped circuits and distributed structures, which are quite common, the parasitic capacitances between adjacent conductors and the capacitances to ground are required. All these parameters can be found from the odd and even mode static capacitances for two parallel coupled lines. The transmission medium is inhomogeneous (the dielectric medium that supports the conductors is suspended in air as seen in Figure 1) so that not only are the system capacitances required with dielectrics present, but also required are these capacitances with all dielectrics removed. From this last, homogeneous, case the line inductance in an assumed TEM mode is found. The methods of calculation outlined here of the even and odd mode capacitances for both homogeneous and inhomogeneous cases are based on a variational approximation and on several conformal transformations. Their use at an interactive time share terminal has proven very valuable in the design of low loss, high performance microwave circuits.

Numerical Analysis of a Dielectric-Loaded Waveguide with a Microstrip Line-Finite-Difference Methods

Abstract: A finite-difference technique is used to evaluate the dispersion of a dielectric-loaded waveguide with a symmetrically placed microstrip line. The magnetic field is also obtained. The results presented are for the fundamental even E/sub z/-odd H/sub z/ mode.

Microwave and millimeter wave hybrid integrated circuits for radio systems

Abstract: Hybrid integration of microwave and millimeter wave circuits is essential for achieving future communication objectives in radio systems. Hybrid integrated circuits are circuits which are manufactured on a single planar substrate. Passive elements are fabricated by partial metallization of the substrate; active devices are inserted by bonding semiconductor diodes or bulk devices to the metal conductors. We discuss the electrical properties of passive line elements on insulating substrates. We also compare the design formulas given with measurements made at 30 GHz, and present the results obtained at 30 GHz with wideband transitions from waveguide to microstrip and the measurements obtained with microstrip IMPATT oscillators and high order varactor multi-pliers in the same frequency range. There are advantages of scaling for building hybrid integrated circuits which we discuss. Oversize models can be built and tested in a relatively short time and substantial savings in turnaround time, required man-power, and cost can be achieved.

Wave Propagation in Microstrip Transmission Lines

Abstract: With the growing popularity of integrated circuits the microstrip transmission line has received wide attention from the microwave community. A common feature that most known analytic solutions share is an assumption that the fundamental mode of propagation resembles a TEM wave closely enough to permit various electrostatic approximations such as conformal mapping, relaxation method, and variational principle. Such solutions although quite useful at low frequencies neglect the fact that the actual propagating modes cannot be TEM. The dispersion of non-TEM waves causes, at microwave frequencies, considerable deviations in effective dielectric constant and velocity of propagation from those values obtained by the electrostatic approximation. In this paper it is shown that the modes that exist on a microstrip transmission line must be hybrid in order that all boundary and continuity conditions be satisfied. In this rigorous analysis the hybrid modes are decomposed into sums of TE and TM (or LSE and LSM) space harmonics, each satisfying the wave equation and the external boundary conditions and their total satisfying the continuity conditions and boundary conditions on the strip. The final outcome of the analysis is a pair of coupled integral equations that are solved numerically. The results indicate that the fundamental hybrid mode is propagating at all frequencies and approaches the known static solutions at low frequencies. However, the correct solution deviates from the static approximation at microwave frequencies. Of particular interest is the fact that as the dielectric constant of the substrate increases the frequency range at which the TEM approximation is valid decreases. The results obtained show close agreement with available experimental data.

Slot Line Application to Miniature Ferrite Devices

Abstract: This paper presents preliminary results and conclusions of experimental investigation of the potential usefulness of slot transmission line. Measurement of phase constant, insertion loss, and other general characteristics are presented and compared with theoretical predictions. Transitions from slot to coax and slot to microstrip are described.One of the more interesting characteristics of slot line, the existence of an elliptically polarized H field, is applied in planar ferrite phase shifter design. Experimental data are presented including preliminary latched phase shift results.

Microstrip phase shifter having switchable path lengths

Abstract: A microstrip phase shifter is inserted in a waveguide aperture, the phase shifting network consists of lightweight transmission line sections which can be switched by microwave diodes to provide the required phase shift. The diodes are switched in pairs, forward or back biased, so that the wave will traverse through a given path to complete the phase shifting according to the switched pair of the diodes.

A Frequency-Stabilized Microwave Band-Rejection Filter Using High Dielectric Constant Resonators

Abstract: The high permittivity dielectric resonator is a low loss microwave filter element whose size is substantiality less than metal waveguide cavities. Temperature stabilizing their resonant frequency increases the applicability of such elements. A temperature compensated 3-section band-rejection filter using dielectric resonators has been fabricated and tested. The measured electrical performance was comparable to metal waveguide filters and the frequency stability for temperature variations was comparable to brass waveguide cavity filters which are not temperature compensated.

Broadband circulator or isolator of the strip line or microstrip type

Abstract: A microwave wide band circulator or isolator device of the strip line or microstrip type wherein the circuit is planar and has a plurality of outwardly tapering legs each of which constitutes a port. Ferrimagnetic or gyromagnetic material is provided overlying a substantial portion of the circuit including at least substantially all of the portion thereof functioning as the input and output ports of the device. The energy in the device propagates along the edges thereof, and accordingly the edges are designed to be free of abrupt changes in order that there be no abrupt impedance changes in the circuit. Uniformity of the field within the device utilizing relatively small magnets is achieved by a ground plane structure wherein the portion thereof in contact with the magnet and the gyromagnetic medium is formed from a highly permeable material while the remainder of the ground plane structure is formed from a nonmagnetic material. The peak power handling capability of the device may be increased by utilizing a gyromagnetic medium formed from two different materials chosen for respective optimum forward and reverse propagation characteristics, while the average power handling capability may be improved by means of a unique load structure.

Flexible stripline transmission line

Abstract: A stripline transmission line is constructed so that the individual conducting and insulating portions of the stripline are free to move relative to each other. This form of construction permits the stripline to be bent to a very small radius without distortion or degradation of its electrical characteristics.

Fourier analysis of a dielectric-loaded waveguide with a microstrip line

Abstract: A Fourier analysis of a symmetrically placed microstrip line in a dielectric-loaded guide is performed. Computed results of the dispersion for the fundamental even Ez-odd Hz mode are presented.

A general method for obtaining impedance and coupling characteristics of practical microstrip and triplate transmission line configurations

Abstract: In order to design an interconnection system for nanosecond-risetime logic circuitry, it is necessary to obtain a balance between impedance variations, propagation velocities, and crosstalk levels so as to achieve the best system speed as well as system speed control. To accomplish this, it is necessary to relate the electrical material properties and physical dimensions of the connections to characteristic impedances, propagation velocities, and crosstalk coupling coefficients. Two practical transmission line configurations: the microstrip line, which is coated for physical protection, and the offset or unsymmetrical triplate line, are being fabricated by mass production techniques. Because of the close control required and the many factors affecting impedance and coupling, these configurations require accurate means for predicting their characteristics. An improved "subintervals" technique and a series approximating the Green's function have been combinedto yield a single practical computer algorithm. Excellent agreement has been obtained in comparing the results of computations with large scale-model transmission line measurements. The method is quite general because dimensions, conductor shapes, and dielectric properties may vary widely.

Microstrip iris directional coupler

Abstract: A microwave iris directional coupler on microstrip having high directivity is disclosed. The device is primarily for use in single ground plane microstrip transmission lines of the type commonly used for microwave hybrid integrated circuits. It has an iris between two lines separated by a common ground plane, such that each line forms a separate transmission line with the common ground plane and is completely isolated from each other, beyond the open portion of the iris.

High-speed impedance-compensated circuits

Abstract: Impedance-compensated circuits for high frequency microstrip signal transmission systems comprising a dielectric board of suitable thickness depending upon the dielectric constant of the material of the board and the frequency of the signals to be transmitted within the system. A ground conductor plate is attached to one planar surface of the dielectric board. The other planar surface of the dielectric board is adapted to receive and have affixed thereto any of a plurality of combinations of signal-conducting elements. The signal-conducting elements have predetermined cross-sectional areas depending upon the signals to be transmitted within the system. Due to microminiature construction, the signal-conducting elements may be provided with lead and circuit-connecting areas of increased size to facilitate making electrical connections for devices to be attached with the elements. The impedance changes due to the increased size of areas are compensated for by means of slots or apertures in the ground conductor plate opposite or in the vicinity of the connecting areas.

Analysis of linear microstrip using an arbitrary ferromagnetic substance as the substrate

Abstract: A Green's function of the vector potential for a microstrip is derived on the basis of the image theory after Silvester and the duality property of electric and magnetic fields of the TEM mode. It is also shown that the stationary equation similar to the variational equation for the electrostatic capacitance of the microstrip is given for its inductance with a magnetic substrate.

Microstrip High-Power High-Efficiency Avalanche-Diode Oscillator

Abstract: A simple microstrip oscillator circuit has been designed and operated satisfactorily with high-power high-efficiency avalanche diodes. The power output obtained from a single diode chip is ahout 100 watts at 1 GHz with efficiencies of 25 to 30 percent. Mechanical tuning capability of a few hundred megahertz and a combined power output from series-connected diodes have been demonstrated using the circuit. An essential part of the circuit is a low-pass filter tuning section which enables the circuit to support high-order harmonics including the transit-time frequency and prevents them from getting to the load. Probe measurements of the electric field show strong second as well as third harmonics inside the circuit.

Variation of microstrip impedance with strip thickness

Abstract: The letter indicates the way in which the characteristic impedance of single and coupled microstrip can vary with strip thickness, and points out that, in many cases of current practical interest, in both computer-circuit and microwave technologies, such variation is too large to be ignored without giving rise to serious error. Some typical graphs are given to illustrate this.

Dielectric loss in hybrid integrated circuits

Abstract: The dielectric loss is of importance in hybrid integrated circuits which require small attenuation. Such circuits are usually built with microstrip or suspended microstrip transmission lines. It is shown that the dielectric loss can be computed from the loss tangent tan δ of the dielectric substrate and the partial derivate δe eff /δe r where e eff is the effective dielectric constant and e r the relative dielectric constant of the substrate. The effective loss tangent, the unloaded dielectric Q and the attenuation per unit length are given for microstrip and suspended microstrip transmission lines.

Hybrid Integrated 10-Watt CW Broad-Band Power Source at S Band

Abstract: An S-band CW power source consisting of transistor-amplifier-driven varactor-doubler chains fabricated in hybrid integrated form is described. The source employs a microstrip package for high-power transistors, which has good heat sinking and low parasitic reactance and which permits direct paralleling of transistors. A breadboard model of the power source consisting of hybrid integrated components interconnected by coaxial lines produced a CW output of 9.8 watts at 3000 MHz with a 1-dB bandwidth of 6.7 percent and a dc to RF efficiency ranging from 9 to 14.5 percent over the band. The required RF input power to the module was 600 mW centered at 1500 MHz.

Reflection phase shifter utilizing microstrip directional coupler

Abstract: DESCRIBED IS A REFLECTIVE PHASE SHIFTER, UTILIZING MICROSTRIP TRANSMISSION LINES, WHICH ALLOWS FOR A CONTINUOUSLY VARIABLE DIFFERENTIAL PHASE SHIFT OVER A GIVEN RANGE. THE BASIC ELEMENTS OF THE DEVICE ARE (1) A MICROSTRIP QUARTERWAVELENGTH PARALLEL-LINE DIRECTIONAL COUPLER FORMED ON A SEMICONDUCTIVE SUBSTRATE AND HAVING THREE OF ITS FOUR ARMS OF SPECIFIC LENGTH AND EITHER OPEN-ENDED OR TERMINATED IN SHORTS, (2) A DISTRIBUTED P-N JUNCTION FORMED IN THE SEMICONDUCTIVE SUBSTRATE IN THE COUPLING REGION BETWEEN THE TWO PARALLEL MICROSTRIPS OF THE COUPLER AND (3) AN EXTERNAL DIRECT CURRENT VOLTAGE SOURCE FOR BIASING THE P-N JUNCTION TO CHANGE THE COUPLING CAPACITANCE BETWEEN THE PARALLEL MICROSTRIPS.

Yig resonator microstrip coupling device

Abstract: A microstrip manifold providing a plurality of frequency selective outputs from a single input signal including a common input microstrip transmission line terminated at one end and a plurality of output microstrip transmission lines disposed substantially normal to the input transmission line and coupled thereto by means of respective yttrium iron garnet (YIG) sphere resonators, each being tuned to a predetermined resonant frequency by a separate magnetic field to provide isolation between each of the output transmission lines Additionally, each of the output transmission lines are terminated at a short circuit in proximity to the respective YIG sphere The input conductor is not grounded at the YIG spheres but is terminated at the end of the line