By Topic

Microwave Theory and Techniques, IEEE Transactions on

Issue 1 • Date Jan. 1989

Filter Results

Displaying Results 1 - 25 of 32
  • Comments on "Analysis of nonreciprocal coupled image lines" [with reply]

    Publication Year: 1989
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (107 KB)  

    For the original article see ibid., vol.MTT-35, no.7, p.629-35, 1987. The commenters claim that the results given by D.B. Sillars and L.E. Davis violate the reciprocity theorem because the analysis is based on an erroneous interpretation of the solution of the wave equation in the ferrite medium. The authors reply that they excited the odd and even modes separately in coupled-slot finline and that over the range of conditions which they explored, they found that, unlike the even mode, the odd mode showed negligible nonreciprocal behavior.<> View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An improved algorithm for the computer-aided design of coupled slab lines

    Publication Year: 1989 , Page(s): 258 - 261
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    Improved analytical formulas for the computer-aided design of parallel coupled slab lines are presented. They make it possible to calculate the geometrical dimensions of the lines for given characteristic impedances Z0e and Z0o . The design of lines under consideration is equivalent to solving two nonlinear equations with the diameter of the rods and the width of the slot as unknown variables. For this purpose conventional numerical methods can be applied. It is concluded that the derived formulas ensure a good agreement of calculations with accurate numerical results for a wide range of geometrical dimensions of the lines. A Basic listing for the CSL computer program is given as an example of the design method View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Cutoff spaces of elliptical gyromagnetic planar circuits and waveguides using finite elements

    Publication Year: 1989 , Page(s): 71 - 80
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    The finite-element method is used to evaluate the cutoff spaces of elliptical magnetized planar circuits with electric and magnetic walls in all combinations. A knowledge of the four possible solutions and of the rules governing the intersections of cutoff branches in the cutoff spaces is sufficient for a complete description of the related elliptical gyromagnetic waveguide with either an electric or a magnetic wall. It is also demonstrated that the demagnetized and split cutoff numbers of the resonator with magnetic sidewall and top and bottom electric walls are sufficient for the approximate description of the split phase constants of the dominant mode in the related weakly magnetized gyromagnetic waveguide problem with either a magnetic or an electric wall View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Electromagnetic deposition in an anatomically based model of man for leakage fields of a parallel-plate dielectric heater

    Publication Year: 1989 , Page(s): 174 - 180
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (596 KB)  

    An anatomically based 5628-cell model of a human being was used to calculate local, layer-averaged, and whole-body-averaged specific absorption rates and internal RF currents at 27.12 and 40.68 MHz for spatially variable electromagnetic fields of a parallel-plate applicator representative of RF dielectric heaters used in industry. The conditions of exposure of the man model considered are: isolated from ground, shoe-wearing condition, feet in contact with ground, and an additional grounded top plate 13.1 cm above the head to simulate screen rooms that are occasionally used for RF heaters. Since peak E fields as high as 1000-2700 V/m have been measured at locations typically occupied by the operator, significant internal RF currents on the order of 0.5-2.3 A are projected for the operators. Measurements of the foot currents at 27.12 and 40.68 MHz for a human subject are in reasonable agreement with the calculated values for the various conditions of exposure View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A broad-band printed circuit hybrid ring power divider

    Publication Year: 1989 , Page(s): 112 - 117
    Cited by:  Papers (26)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    The design of a broadband ring power divider that provides substantial improvement in coupling and phase characteristics over a wide frequency range compared to that of a conventional hybrid ring is presented. It is shown that the new power divider design can be easily constructed using realizable impedances and is applicable to both equal and unequal power divisions. Experimental verification of the broadband power divider was achieved in a stripline configuration at Ku-band for an equal power divider and a 3-dB power divider. Close agreement was observed between theoretical and experimental results for both of the power dividers. The usable bandwidth of the broadband power divider is approximately 45%. It is concluded that this broadband power divider is particularly suited for a narrowband low-sidelobe antenna array beam-forming network, for it provides substantially improved amplitude and phase characteristics, a requirement for low-sidelobe array antennas, and good isolation between output ports View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the application of complex resistive boundary conditions to model transmission lines consisting of very thin superconductors

    Publication Year: 1989 , Page(s): 181 - 190
    Cited by:  Papers (61)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (840 KB)  

    A resistive boundary condition for the case where the resistivity is assumed to be a complex quantity is shown to be an accurate model for a superconducting film which is thin compared to the super-conducting penetration depth. The imaginary part of the conductivity is the dominant terms and is a measure of the inductive energy stored in the superconductor. Numerical solutions of superconducting microstrip are obtained and compared to experimental results and to analytic solutions for superconducting parallel-plate waveguides. Excellent agreement is found between experimental, analytical, and numerical results View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Variational analysis of dielectrically loaded multidepth corrugated waveguides

    Publication Year: 1989 , Page(s): 191 - 197
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (600 KB)  

    The propagation behavior in a multidepth corrugated waveguide is analyzed on the basis of the theory of nonstandard eigenvalues and variational methods. This method is tested for an empty dual-depth corrugated guide. The test results have been previously calculated in the literature by using surface impedance and space harmonic methods. These methods are summarized here. Space harmonic formulas are rederived in the form where the fundamental surface admittance component is separated from the higher order terms. It is found that, with elementary trial functions, very accurate dispersion relations can be obtained by the variational method. The method is then extended to a tridepth guide operating in three different frequency bands and to dielectrically loaded dual-depth and tridepth guides View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A CAD-oriented method for noise figure computation of two-ports with any internal topology

    Publication Year: 1989 , Page(s): 15 - 20
    Cited by:  Papers (14)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    A method for computer-aided noise analysis and an algorithm for the noise-parameter computation of two-ports with any internal topology are discussed. The set of noise parameters that can be calculated by the method includes the noise figure, the correlation matrix of the outgoing noise waves at the input and output ports, the minimum noise figure, the optimum signal reflection coefficient, and the parameter N. The approach is applicable to circuits composed of any number of passive linear multiports and active liner two-port devices. The noise analysis is based on the scattering-matrix description for circuit elements and wave representation for noise. At microwave frequencies, a treatment of noise in terms of waves is more attractive View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A 2-18 GHz low-noise/high-gain amplifier module

    Publication Year: 1989 , Page(s): 198 - 207
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1056 KB)  

    The effectiveness of the two-tier matrix amplifier as a very-low-noise device with very high associated gains across multioctave frequency bands is theoretically and experimentally demonstrated. Experimental modules whose topology is based on a computer-optimized design exhibit an average noise figure of F=3.5 dB with an associated average gain of G=17.8 dB across the 2-18 GHz frequency band. These state-of-the-art results were achieved with GaAs MESFETs whose minimum noise figure is F=2.2 dB at 18 GHz and whose gate dimensions are 0.25×200 μm. The design considerations and the test results are discussed in detail View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Intelligent alignment of waveguide filters using a machine learning approach

    Publication Year: 1989 , Page(s): 166 - 173
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (636 KB)  

    The authors investigate the application of a machine learning system to the tuning of waveguide filters. This system uses techniques from pattern recognition and adaptive signal processing. The manual tuning of the waveguide filters is very time consuming and expensive and a skilled operator is required. Here, the machine learning system is adapted in such a way that it can assist an unskilled operator to perform fast and accurate tuning of these filters. The machine learning approach is based on the manipulation of some raw data to extract a set of salient features that have strong significance in the behavior of the filters. These features are derived visually, by comparing the characteristics of a tuned filter to those of a faulty filter with known levels of maladjustments View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Open-ended coaxial exposure device for applying RF/microwave fields to very small biological preparations

    Publication Year: 1989 , Page(s): 102 - 111
    Cited by:  Papers (4)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1040 KB)  

    An easily fabricated open-ended coaxial exposure device for applying radiofrequency/microwave energy to very small biological preparations is described. The device utilizes the fringing fields of a coaxial cable opening into a ground plane. Operation of the device is easily integrated into standard laboratory procedures in order to: observe a biological specimen; monitor temperature; regulate temperature, pH, and pO2; and record cellular membrane potentials. The electromagnetic field configuration of the device leads to elimination of detectable interaction with microelectrodes. Measured patterns of electric field and specific absorption rate are given for a device built with quarter-inch semirigid coaxial cable and operating at 2450 MHz. Comparison is made to previous exposure devices for small biological preparations. The particular advantages of the open-ended coaxial exposure device over previous devices are the easy access to the preparation during exposure and the minimal, if any, coupling RF/microwave fields to microelectrodes used in electrophysiological studies View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Generation of high-power broad-band microwave pulses by picosecond optoelectronic technique

    Publication Year: 1989 , Page(s): 43 - 50
    Cited by:  Papers (6)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    A single-picosecond GaAs photoconductive switch is used to pulse excite a microwave resonant cavity, thus generating a variety of RF (radiofrequency) waveforms with picosecond synchronization. The length of the transmission line that connects the photoconductive switch and the cavity and the strength of input/output cavity coupling elements provide for continuous variation of the frequency distribution of the generated RF power. The generation of greater than 7-kW broadband microwave bursts is demonstrated View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Oscillators using magnetostatic-wave active tapped delay lines

    Publication Year: 1989 , Page(s): 239 - 243
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    A novel oscillator that combines a magnetostatic wave (MSW) tapped delay line with GaAs monolithic microwave integrated circuits has been fabricated. This oscillator incorporates an external feedback loop that is extremely short and provides multiple outputs delayed in time by the MSW delay line. The oscillator is tunable from 2.76 to 2.95 GHz, and the 3-dB bandwidth of the oscillation is approximately 10 kHz View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Spectral-domain analysis of harmonic effects in superconducting quasiparticle mixers

    Publication Year: 1989 , Page(s): 231 - 238
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    An algorithm was developed for calculating the harmonic performance of superconducting quasiparticle millimeter-wave mixers. The scheme uses harmonic balance to determine the steady-state waveform of the large-amplitude voltage which is induced across the tunnel junction by the local oscillator source. A key feature of the algorithm is that the large-signal tunneling-current calculations are done in the frequency domain rather than in the time domain, and this approach leads to numerically efficient computer simulations. The superiority of the spectral-domain method is particularly pronounced when modeling mixers that incorporate high-quality tunnel junctions with very sharp DC nonlinearities. A simplified mixer simulation was performed to determine the range of ωCR products for which harmonic effects are likely to be important View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Determination of the correlation spectrum of oscillators with low noise

    Publication Year: 1989 , Page(s): 90 - 101
    Cited by:  Papers (58)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (756 KB)  

    A general expression for the correlation spectrum of an oscillator, described by a set of nonlinear ordinary differential equations with intrinsic noise sources, is derived by a first-order perturbation theory. The analytical derivations are well suited to the numerical determination of the correlation spectrum by Poincare mapping methods. The theory is applied to a lumped circuit model of Colpitts oscillator. It is concluded that the noise behavior of complex oscillator circuits used in microwave engineering can be simulated by the derived method View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Finite element formulation for guided-wave problems using transverse electric field component

    Publication Year: 1989 , Page(s): 256 - 258
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    A finite-element formulation for electromagnetic waveguide problems is described using the transverse electric field component. In this approach, the electric field components can be directly obtained as an eigenvector of a matrix eigenvalue problem. Furthermore, no spurious solutions are involved in the entire region of a propagation diagram, and the dimension of the final matrix equation is reduced to two thirds that of the penalty function method. The validity of the present formulation was confirmed via applications to some canonical waveguide problems View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Spectral-domain computation of characteristic impedances and multiport parameters of multiple coupled microstrip lines

    Publication Year: 1989 , Page(s): 215 - 221
    Cited by:  Papers (55)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    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 View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reflection coefficient of a waveguide with slightly uneven walls

    Publication Year: 1989 , Page(s): 244 - 252
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    First-order results are derived for the reflection coefficient of a waveguide with slightly uneven walls. Specific analytical and numerical results are given for rectangular waveguides and coaxial transmission lines. Simple upper bounds are given for reflection coefficients in terms of the maximum deviation of the waveguide. For typical tolerances the reflection coefficients are very small (<10 -3), but the results are important in precise six-port measurements View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optically CW-induced losses in semiconductor coplanar waveguides

    Publication Year: 1989 , Page(s): 139 - 149
    Cited by:  Papers (23)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (996 KB)  

    The authors present a quasi-static analysis of photoinduced wave attenuation in a continuously illuminated coplanar waveguide transmission line on a semiconductor substrate, using a conformal mapping technique. The relevant effects of charge carrier diffusion and surface recombination on photoconductivity and plasma penetration depth have been incorporated into the theory. This allows a quantitative estimate of optically induced losses as a function of the various light-source and substrate parameters by means of numerically calculated diagrams. In the particular case of small-plasma-depth excitation, an appropriate, analytical expression for the light-controlled attenuation constant is presented. Initial experimental results are in relatively good agreement with the theory View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Analysis of dielectric guiding structures by the iterative eigenfunction expansion method

    Publication Year: 1989 , Page(s): 63 - 70
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    Numerical results demonstrating capabilities of a recently developed method for determining guided modes of dielectric waveguides are presented. Apart from accuracy tests for the single-core waveguides, examples of the wavelength-selective coupler, the directional coupler with an adhesive layer, and the side-pit structure are briefly analyzed. The theoretical background of the iterative eigenfunction expansion method (IEEM) and the comprehensive description of the numerical algorithm are also given. Because it is efficient, highly accurate, and versatile, the IEEM proved to be useful in the analysis of various dielectric guiding structures View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A partial variational approach for arbitrary discontinuities in planar dielectric waveguides

    Publication Year: 1989 , Page(s): 208 - 214
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (504 KB)  

    A novel approach for analyzing arbitrary discontinuities in planar dielectric waveguides is proposed that uses the finite-element method along with the frontal solution technique. On the basis of the partial variational principle (PVP), the fields interior and exterior to the discontinuity finite-element region can be treated independently and eventually can be coupled. The interior fields are expanded by the finite-element nodal values and the corresponding local bases, while the exterior ones are handled by an approach combining modal expansion and Green's function. In numerical computation, the continuous spectra of the waveguide modes are discretized by the Laguerre expansion method. To check the correctness of the present analysis, two numerical results are compared to those of other methods. The scattering characteristics of several linearly tapered discontinuities, such as transformers and feed structures, are analyzed and compared to those having step junctions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A new analytic design technique for two- and three-way warped mode combine directional couplers

    Publication Year: 1989 , Page(s): 34 - 42
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (708 KB)  

    An analytic technique of designing ultra-wideband warped-mode two way and three-way microwave directional couplers is presented. With this matrix method it is possible to design couplers for any level of coupling by choosing a warping angle appropriate to the desired output amplitudes. The design technique involves obtaining a wave propagation matrix in analytical form as a function of the taper parameter, which in turn is a function of distance along the coupler length. The line parameters and the forward scattering matrix are then determined from the wave propagation matrix at any distance from the beginning of the coupler. The method is demonstrated for couplers using microstrip coupled comblines. The computed and the measured performances of a two-way and a three-way microstrip combline are presented for equal power splitting. These couplers were found to work between 1.5 and 8.5 GHz View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Six-port and four-port reflectometers for complex permittivity measurements at submillimeter wavelengths

    Publication Year: 1989 , Page(s): 222 - 230
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (940 KB)  

    The frequency range of six-port reflectometry is extended into the submillimeter wavelength range. The complex permittivity of low-loss microwave materials is determined using novel six-port and four-port reflectometers. These either consist of quasi-optical components or utilize oversized waveguide techniques. Permittivity measurements of materials possessing a wide range of values of ε' (2 to 7) and of the loss tangent (0.0003 to 0.03) were carried out at frequencies of about 380 GHz to 390 GHz. Good agreement with published permittivity data is shown. Moreover, the equivalance of the simple waveguide four-port reflectometer (which is preferred because of its easy handling and high stability against temperature fluctuations) to the quasi-optical reflectometers is shown View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • On the mode coupling in longitudinally magnetized waveguiding structures

    Publication Year: 1989 , Page(s): 159 - 165
    Cited by:  Papers (34)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1124 KB)  

    Propagation in waveguiding structures containing gyromagnetic material with longitudinal magnetization is analyzed in terms of the coupling between modes having different symmetry properties. It is found that the wave supported by a symmetrical structure of two coupled guides is a combination of the even and odd modes propagating in an isotropic structure. The gyromagnetic medium causes the coupling between the modes, and the energy of the wave is periodically transferred from one mode to another, which in turn results in the exchange of energy between guides. The proposed mathematical model explains the operation of novel nonreciprocal devices View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Full-wave, finite element analysis of irregular microstrip discontinuities

    Publication Year: 1989 , Page(s): 81 - 89
    Cited by:  Papers (79)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (720 KB)  

    Finite-element expansion currents are used to formulate a full-wave analysis of microstrip discontinuities. With this approach, a rigorous analysis of fairly irregular structures is possible, including radiation and surface wave effects as well as coupling between closely spaced junctions. The step, stub, and bent-stub discontinuities are analyzed using this technique. Measurements are made of three stub structures. Measured resonant frequencies agree with full-wave calculations to within 2% when the nominal measured dielectric constant and structure dimensions are used as input. Using the absolute worst case dielectric constants and dimensions as input gives an error of 3% for the low-frequency stub and less than that for the other stubs View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The IEEE Transactions on Microwave Theory and Techniques focuses on that part of engineering and theory associated with microwave/millimeter-wave components, devices, circuits, and systems involving the generation, modulation, demodulation, control, transmission, and detection of microwave signals. This includes scientific, technical, and industrial, activities. Microwave theory and techniques relates to electromagnetic waves usually in the frequency region between a few MHz and a THz; other spectral regions and wave types are included within the scope of the Society whenever basic microwave theory and techniques can yield useful results. Generally, this occurs in the theory of wave propagation in structures with dimensions comparable to a wavelength, and in the related techniques for analysis and design..

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Dominique Schreurs
Dominique.Schreurs@ieee.org

Editor-in-Chief
Jenshan Lin
jenshan@ieee.org