Showing papers on "Microstrip published in 1977"

Transmission-Line Properties of a Strip on a Dielectric Sheet on a Plane

Abstract: The subject is a strip Iine formed of a strip and a parallel ground plane separated by a dielectric sheet (commonly termed "microstrip"). Building on the author's earlier papers all the significant properties are formulated in explicit form for practical applications. This may mean synthesis and/or analysis. Each formula is a close approximation for all shape ratios, obtained by a gradual transition between theoretical forms for the extremes of narrow and wide strips. The effect of thickness is formulated to a second-order approximation. Then the result is subjected to numerical differentiation for simple evaluation of the magnetic-loss power factor from the skin depth. The transition formulas are tested against derived formulas for overlapping narrow and wide ranges of shape. Some of these formulas are restated from the earlier derivations and others are derived herein. The latter include the second-order approximation for a narrow thin strip, and a close approximation for a narrow or wide square cross section in comparison with a circular cross section. Graphs are given for practical purposes, showing the wave resistance and magnetic loss for a wide range of shape and dielectric. For numerical reading, the formulas are suited for programming on a digital pocket calculator.

A theoretical investigation of the rectangular microstrip antenna element

Abstract: A theoretical treatment of the rectangular microstrip radiating element has been performed. The element has been modeled as a line resonator with radiation taking place at the open-circuited ends. This has been verified by using a liquid crystal visual detector. With the simplified model, the input impedance and the far fields have been calculated for different resonant modes. The interaction between the radiating ends will effect the input impedance, and this has been considered by defining a mutual conductance. Also, a mutual conductance between microstrip elements has been expressed in far-field quantities and plotted as a function of spacing along the E - and H - planes. The directivity of an isolated element has been calculated as the directivity of one radiating end times the contribution due to the array factor.

On the Analysis of Symmetrical Three-Line Microstrip Circuits

Abstract: The immittance parameters for the case of symmetrical coupled three-line microstrip or other inhomogeneous six-port structures are derived in terms of the normal modes of the coupled system. The analytical results obtained reduce to the heretofore known results when the line parameters are interrelated in a specified manner, and should be useful in the study and accurate design of three-line couplers and other microwave circuit elements.

Simple and accurate formulas for a microstrip with finite strip thickness

Abstract: 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.

A Method for Calculating the Frequency-Dependent Properties of Microstrip Discontinuities

Abstract: A method is described for calculating the dynamical (frequency-dependent) properties of various microstrip discontinuities such as unsymmetrical crossings, T junctions, right-angle bends, impedance steps, and filter elements. The method is applied to an unsymmetrical T junction with three different linewidths. Using a waveguide model with frequency-dependent parameters, a field matching method proposed by Kuhn is employed to compute the scattering matrix of the structures. The elements of the scattering matrix calculated in this way differ from those derived from static methods by a higher frequency dependence, especially for frequencies near the cutoff frequencies of the higher order modes on the microstrip lines. The theoretical results are compared with measurements, and theory and experiment are found to correspond closely.

Design of microstrip spur-line band-stop filters

Abstract: The paper describes the design of a new class of microstrip bandstop filter. This filter is a very compact structure, it radiates power significantly less than conventional shunt-stub and coupled-line filters and is also less susceptible to the influence of other components and lines in its vicinity.

Spectral Domain Solution of Arbitrary Coplanar Transmission Line with Multilayer Substrate (Short Papers)

Abstract: A hybrid mode analysis is presented for a multilayer dielectric within a rectangular conducting box. An arbitrary set of conductors may be distributed along the lower surface of the top layer, so that single or coupled forms may be analyzed of slot line, microstrip, or coplanar waveguide. The analysis combines a transfer-matrix approach with the spectral domain method to give a versatile and efficient solution. CPU time on an IBM 360/65 is about 1 s per layer of substrate, for a single slot or strip, at one frequency.

A Method for Broad-Band Matching of Microstrip Differential Phase Shifters

Abstract: Meander-line phase shifters in microstrip are not well matched, because of the phase-velocity difference between the odd and the even mode in the coupled-line region. A stepped impedance design is introduced which allows one to realize, for example, a quarter-wavelength 90/spl deg/ Schiffman phase shifter with three sections, having, theoretically, a return loss better than 30 dB over a 1:5 bandwidth. Design equations are given and are confirmed by measurements on microwave integrated circuits in the frequency range 2-10 GHz.

Dissipation Loss Effects in Isolated and Coupled Transmission Lines

Abstract: This paper describes a computer-aided analysis of dissipation losses in uniform isolated or coupled transmission lines for microwave and millimeter-wave integrated-circuit applications. The analysis employs a quasi-TEM model for isolated transmission lines and for the even- and odd-mode transmission lines associated with coupled-line structures. The conductor and dielectric losses are then related to equivalent charge density distributions, which are evaluated using a method-of-moments solution. The transmission lines treated by this analysis may contain any number of Iossy conductors and inhomogeneous dielectrics, consisting of any number of different homogeneous dielectric regions. A development is provided to explicitly relate the four-port terminal-electrical performance of directional couplers to evaluated even- and odd- mode loss coefficients. Examples of evaluated losses are presented in graphical form for isolated lines of inverted microstrip and trapped inverted microstrip and edge-coupled microstrip with a dielectric overlay. The analysis accuracy has been confirmed using microstrip and coplanar waveguide configurations. A comparison is made of the total loss characteristics for microstrip, coplanar waveguide, inverted microstrip, and trapped inverted microstrip. Calculations are compared with measurements for the coupled-line structure. Accuracy of the solution and suggested refinements are discussed. Five computer programs are documented.

Equivalent Series Inductivity of a Narrow Transverse Slit in Microstrip

Abstract: The series inductivity introduced by a narrow transverse slit in a microstrip transmission line has been evaluated theoretically, and a simple formula for this inductivity is presented Experimental results for slits of different depth obtained with the resonant ring method compare well with theory Applications of such a slit include the fine tuning of the electrical length of stubs and the compensation of excess capacitances at discontinuities

Microstrip radiator with folded resonant cavity

Abstract: A resonant microstrip radiator wherein the size of the radiator is reduced in the resonant or non-resonant dimensions, or both, without reducing the effective resonant dimension or substantially lowering the efficiency of the radiator. Reduction of the resonant dimension is provided by folding the resonant cavity, while reduction of the non-resonant dimension is facilitated by utilization of a low density, low loss dielectric, such that the loss resistance of the element is appreciable with respect to the radiation resistance of the element. Also disclosed are interdigitated antenna structures and provisions for circularly or elliptically polarized radiation.

Design of waveguide-to-microstrip transitions specially suited to millimetre-wave applications

Abstract: A design procedure for millimetre waveguide-to-microstrip transitions is presented. The analysis is such that existing design information, readily available in practical curve format, can be directly applied. In addition, the procedure can be adapted to all physically realisable microstrip impedances, as well as substrate materials and thicknesses.

Adjustable transmission line filter and method of constructing same

Abstract: Transmission line filter adapted to respond to a predetermined frequency, having a resonator conducting layer with dielectric material on opposite sides thereof and a ground plane conducting layer on the outside surfaces of the dielectric material. The filter may be of the stripline or microstrip type having a resonator constructed so that it tends to operate at a frequency different from the desired frequency, and which is not accessible for trimming after the filter is constructed. The ground plane layer is accessible so that a portion thereof can be removed after the filter is constructed to change the electrical parameters of the line formed by the resonator and the ground plane layer to change the response frequency of the filter. Alternatively, conducting material can be added to an opening in the ground plane conducting layer to change the response frequency of the filter. The ground plane layer can be removed by a sand blast, laser beam or other means, and can be added by the use of conductive paint, to trim the frequency of the filter after it is constructed.

Bandpass filtering with multibar magnetostatic-surfacewave microstrip transducers

Abstract: The insertion loss for multibar magnetostatic-surface-wave (m.s.s.w.) transducers has been calculated from a ‘small’-loss microstrip-transmission-line model. Experimental results for 2-bar and 8-bar parallel-strip and 4-bar π transducers are in excellent agreement with theoretical predictions. The 8-bar parallel-strip-transducer delay line gives a major bandpass response at 3.1 GHz, corresponding to an m.s.s.w. wavelength of 300 μm. The insertion loss is 11 dB, the 10 dB bandwidth is 70 MHz and adjacent sidelobes are 16 dB down.

The Radiation of Electromagnetic Power by Microstrip Configurations

Abstract: A new technique for calculating the radiation losses of microstrip configurations is presented. The method applies if the wavelength is large compared to the width of the conducting strip and the thickness of the dielectric wafer. It is shown that the radiated power, which is partly carried by "space waves" and partly by "surface waves," can be computed in terms of the specific inductance and the specific capacitance of the transmission line, without making any assumptions regarding the current distribution in the microstrip. It appears that the fraction of the radiated power carried by surface waves contains the frequency to a higher power than does the fraction carried by space waves and is therefore relatively small. The investigated configurations are the infinitely long transmission line excited by a voltage-slit, the half-wavelength straight resonator, the full-wavelength circular resonator, and the quarter-wavelength hair-pin resonator. It follows that the quality factor of the straight resonator and the circular resonator are inversely proportional to the square of the frequency, whereas the quality factor of the hairpin resonator is inversely proportional to the fourth power of the frequency.

Microstrip antennas and arrays. Part 1: Fundamental action and limitations

Abstract: Consideration of the radiation mechanism of an open-circuit microstrip termination indicates that the terminal-plane region is the dominant radiating aperture. On this basis, the radiation patterns of several types of microstrip radiating elements in rectangular and cylindrical geometry are calculated and substantiated by experiment. In general, the patterns exhibit the characteristics of slot radiators, thus endorsing the action of an end-radiating aperture; the radiation admittance of the latter is obtained by novel measurements of the standing waves in a truncated microstrip line but, when the substrate extends beyond the radiating aperture, substrate surface waves are generated. An analysis of the substrate waves indicates that the side-lobe level of an array of microstrip radiating elements could be limited to around -20 dB, and severe unwanted coupling effects between microstrip circuits are also noted. The use of substrate troughs to reduce the surface-wave generation is discussed, and a strip width-modulation technique proposed to control the array aperture distribution and simplify the feeding configuration. The implications of these present findings on the potential performance of microstrip antenna arrays is discussed and design recommendations made; the latter are investigated in a companion paper.

Cavity excitation utilizing microstrip, strip, or slot line

Abstract: The excitation or coupling of microwave integrated circuits to a cavity or resonator is effected by a substrate forming part of the wall of the cavity and on which there is disposed a microstrip or a strip or a slot line.

A Broad-Band Frequency Divider Using Microwave Varactors

Abstract: A novel configuration using GaAs varactors in a balanced circuit configuration incorporating both coplanar waveguide and microstrip elements permits the construction of microwave frequency dividers which have near-octave divide-by-two bandwidth and excellent response to pulsed RF inputs.

Equivalent Circuit Capacitance of Microstrip Step Change in Width

Abstract: Calculated results which extend existing data on the capacitance of step discontinuity are presented for w/sub 1/ /H of value 0.1, 0.5,1.0, and 2.0, for relative dielectric constants of 15.1, 9.0, 4.0, and 2.3, and for w/sub 2/ /H in the range 0.1-10.0. The quasi-static method of calculation is used, and the excess capacitance associated with the steps is determined by the solution of the integral equation using Green's functions.

Fast Accurate Hybrid Mode Computation of Nonsymmetrical Coupled Microstrip Characteristics

Abstract: A numerically efficient rigorous spectral domain solution of the wave equation is presented for covered and open nonsymmetrical coupled microstrip lines. Dispersion characteristics of the two fundamental quasi-TEM modes existing on this structure are given and found to agree excellently with measurement. In addition, the associated characteristic impedances of the unequal strips to ground and the line losses are computed from the eletromagnetic field. With this set of design data the four-port admittance matrix of a nonsymmetrical coupled line section is calculated taking the different modal phase velocities into account. As an example of application and as a further test for the computed results elementary microstrip bandfilter structures are analyzed.

Branch line directional coupler having an impedance matching network connected to a port

Abstract: The invention is an improvement over the conventional branch guide directional coupler and gives better performance by providing flatter coupling over a broader band. A branch guide (line) directional coupler fundamentally is a four port electrical network. The invention improves the performance of the conventional branch guide coupler by employing matching devices at the ports of the fundamental network. In most embodiments of the invention, it is contemplated that matching devices will be used at each of the ports and that all those matching devices will be of like construction. However, it is not essential that a matching device be employed at every port nor is it essential that all the matching devices be of like construction. For example, in some embodiments of the invention, matching structures need be employed only at the output ports. In the stripline and microstrip embodiments of the invention the matching device can be formed by a half wavelength open-circuited stub in combination with a quarter wavelength transformer or by a short-circuited quarter wavelength stub in combination with a quarter wavelength transformer. Although the invention is described principally in strip line or microstrip form, the invention can also be embodied in waveguide or coaxial form.

Microstrip antennas and arrays. Part 2: New array-design technique

Abstract: Open-circuit terminations on half-wavelength stubs form the radiating elements in a new design technique for linear microstrip microwave arrays. Measured results, on computer-designed resonant and wideband travelling-wave arrays with broadisde beams, demonstrate the technique; the effects of corporate feeds and radomes are also considered. The computer design of medium gain arrays, with H-plane sidelobe levels below about -21 dB, demands characterisation of the microstrip T-junction with an accuracy that is currently unavailabe, and the dimensional precision has to be obtained by experimental means. It is concluded, to date, that the known extraneous sources of radiation do not inhibit the control of H-plane sidelobes to a level of at least -25 dB and the new design technique makes microstrip arrays highly competitive with their conventional waveguide counterparts.

Structure and technique for achieving reduced inductive effect of undesired components of common lead inductance in a semiconductive RF power package

Abstract: An RF power transistor device, or package, which includes a transistor, a capacitor, an electrically insulating but thermally conducting substrate, a metallic ground lead member on the substrate having input output and common portions, a heat sink on which the substrate is mounted and, input and output microstrip conductor means mounted on the heat sink has the common lead inductive effect of at least one component of common lead inductance of the transistor reduced by tightly coupling the input ground current and the input current as by a film of dielectric material such as Kapton or Teflon of about one half mil in thickness. Alternatively the output current and the output ground current may be tightly coupled.

Microwave device provided with a 1/2 lambda resonator

Abstract: A microwave device is disclosed comprising a microstrip line pattern including an open ring forming a 1/2λ resonator having a narrow gap in which the electromagnetic field is closely tied to the ring.

Broadband Frequency Dividers Using Microwave Varactors

Abstract: A novel configuration using GaAs varactors in a balanced circuit incorporating both coplanar waveguide and microstrip elements has permitted the construction of frequency dividers which have near-octave divide-by-two bandwidth and excellent response to pulsed r.f. inputs. The design and performance of such a frequency divider for inputs in the 4 to 8 GHz range is discussed.

Millimeter wave MIC diplexer

Abstract: A millimeter wave MIC diplexer constructed in either stripline or microstrip comprising two edge coupled bandpass filters separated by specific lengths of transmission lines designed to separate two bands of frequencies. Input signals having frequencies within a first band are passed through one of the bandpass filters while being isolated from the other and input signals having frequencies within a second band are passed through the other bandpass filter while being isolated from the first filter.

Magnetostatic Wave Signal Processing

Abstract: A novel technology for analog, real time, signal processing at GHz frequencies is described utilizing the propagation of slow magnetostatic waves in magnetically biased films of yttrium iron garnet, grown by liquid phase epitaxy on substrates of gadolinium gallium garnet. dispersion, attenuation and tunability c haracteristics of these waves are reviewed together with methods for efficient microstrip transduction, controlled tapping and realizing matched terminations. Comparisons are drawn with SAW technology in the context of available parameters and performing non- recursive transversal filtering. Basic experiments on magnetostatic wave propagation in periodic structures, comprised of either etched arrays or metal overlay arrays, both at normal and oblique incidence are described. The paper concludes with a survey of magnetostatic devices for GHz signal processing applications including bandpass filters, resonator-filter s, delay lines, o scillators and The

Stacked antenna structure for radiation of orthogonally polarized signals

Abstract: A resonant circularly or elliptically polarized microstrip radiator wherein the size of the radiator is reduced in the resonant or non-resonant dimensions, or both, without reducing the effective resonant dimension or substantially lowering the efficiency of the radiator. Reduction of the resonant dimension is provided by folding the resonant cavity, while reduction of the non-resonant dimension is facilitated by utilization of a low density, low loss dielectric, such that the loss resistance of the element is appreciable with respect to the radiation resistance of the element. The preferred embodiment comprises interdigitated antenna structures.

Optimim design for a broadband microstrip balun

Abstract: The letter reports calculations of Marchand balun performance which show that bandwidths approaching 50:1 (for a V.S.W.I.?2:1) should be achievable with overlaid microstrip structures. The bandwidth limits (?8:1) reported by previous writers appear to reflect only the inaccessibility of the true optimum to the semiempirical design methods used and the limitations of fabrication on single-thickness card. Preliminary experimental results confirm the theoretical indications.