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Microwave Theory and Techniques, IEEE Transactions on

Issue 6 • Date Jun 1990

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Displaying Results 1 - 25 of 27
  • Dielectric ribbon waveguide: an optimum configuration for ultra-low-loss millimeter/submillimeter dielectric waveguide

    Publication Year: 1990 , Page(s): 691 - 702
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    Dielectric ribbon waveguide supporting the eHE11 dominant model can be made to yield an attenuation constant for this mode of less than 20 dB/km in the millimeter/submillimeter-wavelength range. The waveguide is made with a high-dielectric-constant, low-loss material such as alumina or sapphire. It takes the form of thin dielectric ribbon surrounded by lossless dry air. A detailed theoretical analysis of the attenuation and field extent characteristics for the low-loss dominant eHE11 mode along a ribbon dielectric waveguide was performed using the exact finite-element technique as well as two approximate techniques. Analytical predictions were then verified by measurements on ribbon guides made with rexolite using the highly sensitive cavity resonator method. Excellent agreement was found View full abstract»

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  • An improved model for noise characterization of microwave GaAs FETs

    Publication Year: 1990 , Page(s): 703 - 706
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    A broadband noise model for microwave FETs has been described. The model consists of small-signal lumped elements together with two noise sources. A measurement of broadband S parameters plus a single-frequency measurement of optimum source susceptance can yield enough information to determine the model, although greater accuracy is obtained using additional noise data to determine the precise value of the gate resistance. The model's predictions match well with measured noise parameter data for a high-performance GaAs FET over a wide frequency range View full abstract»

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  • An analytical solution to the microstrip line problem

    Publication Year: 1990 , Page(s): 766 - 769
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB)  

    An analytical method for determining the line capacitance of a microstrip line is presented. The solution is exact, but it is expressed by means of the solution of an infinite system of linear equations whose coefficients are the result of certain numerical quadratures. The analysis is carried out for the case of two dielectric substrates. Changes to include additional stratified layers are readily available using the transfer matrix method described by P.M. van Berg et al. (1985). Comparison of the results obtained using the proposed formula with those obtained using exact formulas (available in particular cases) shows that, in cases of practical interest, it is sufficient to consider only the first two equations in the above-mentioned infinite set of linear equations View full abstract»

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  • X-band 0.5, 1, and 2 watt power amplifiers with marked improvement in power-added efficiency

    Publication Year: 1990 , Page(s): 707 - 711
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    Very efficient X-band MESFET power amplifiers, showing greater power-added efficiency over a wider bandwidth than any X-band amplifiers of comparable output reported to date, are discussed. The amplifiers were designed with attention given to optimum bias, proper harmonic termination, and efficient power combining. These device and design issues are discussed, and a straightforward design method which achieved the increased levels of efficiency is described View full abstract»

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  • An improved GaAs MESFET model for SPICE

    Publication Year: 1990 , Page(s): 822 - 824
    Cited by:  Papers (69)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    A SPICE model for modeling GaAs MESFET devices more accurately is discussed. In particular, small-signal parameters are accurately modeled over a wide range of bias conditions. These results were achieved by modifying the model equations of H. Statz et al. (see IEEE Trans. Electron. Devices, vol.3, no.2, p.160-9, 1987) to better represent the variation of Ids as a function of the applied voltage. The model applies over a large range of pinch-off voltages, allows size scaling of devices, and is suited for modeling R ds changes with frequency. The Statz equations are used to represent diode characteristics and capacitive components of the model View full abstract»

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  • Three-dimensional analysis of a through hole with radiation characteristics by the spatial network method

    Publication Year: 1990 , Page(s): 770 - 778
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (676 KB)  

    Through holes generate complicated distributions of electromagnetic fields owing to their three-dimensional structures. Rigorous vectorial analyses must be performed for three-dimensional fields by using all field components, boundary conditions, and properties of the medium. The spatial network method, which has many features for analysis of three-dimensional electromagnetic fields in the time domain, was applied to this analysis. The variation of Poynting vector distributions near the through hole is simulated in the time domain. From the distribution of the electric field on the top plane of the through hole containing the connected stripline and the land, the far-field patterns are computed by the Fourier transform. Fundamental characteristics of the radiation from the through hole are thereby obtained View full abstract»

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  • Frequency-domain bivariate generalized power series analysis of nonlinear analog circuits

    Publication Year: 1990 , Page(s): 815 - 818
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    Bivariate generalized power series analysis is introduced for the analysis and behavioral modeling of nonlinear analog circuits and systems. It can be used to model analog subsystems and is compatible with circuit simulation, thereby allowing full circuits and behaviorally modeled analog subcircuits to be simulated together in an analog circuit/system simulator. The entire analysis is performed in the frequency domain, and arbitrary nonlinear circuits and any number of noncommensurable input frequencies can be accommodated. A diode ring demodulator is analyzed as an example View full abstract»

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  • Analysis of the junction between smooth and corrugated cylindrical waveguides in mode converters

    Publication Year: 1990 , Page(s): 800 - 802
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (252 KB)  

    A method for determining the scattering matrix of the junction between smooth and corrugated cylindrical waveguides is developed. The model is based on expanding the modal fields for the corrugated waveguide into eigenfunctions of the transmission matrix of a waveguide unit cell. This method, used in conjunction with usual techniques for evaluating the scattering matrix of mode converters, is shown to improve the precision of results obtained by rendering uniform the accuracy of the models applied in the calculations. The analysis is now valid for any size of corrugation depth, and the frequency band, of applicability is enlarged accordingly View full abstract»

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  • Semidistributed model of millimeter-wave FET for parameter and noise figure predictions

    Publication Year: 1990 , Page(s): 748 - 753
    Cited by:  Papers (11)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    An electrical FET model, derived from a partition of the actual transistor along its gate width into N identical sections, is presented. This sliced model has two important advantages compared to distributed models: first, the derivation of its element values is obtained by directly applying Kirchhoff's laws, and second, inserting the noise sources is easy and makes possible the prediction of the FET noise parameters. An example that shows good agreement between minimum noise figures derived from the sliced model and from the Fukui formula in the range 18-40 GHz is given View full abstract»

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  • Finite-difference method without spurious solutions for the hybrid-mode analysis of diffused channel waveguides

    Publication Year: 1990 , Page(s): 722 - 729
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    Diffused dielectric channel waveguides with an arbitrarily varying refractive index profile in the cross-sectional plane are analyzed with a rigorous finite-difference method. The method is formulated in terms of the wave equation for the transverse components of the magnetic field. This leads to an eigenvalue problem where the nonphysical, spurious modes do not appear. The analysis includes the complete set of hybrid modes, takes mode-conversion effects and complex waves into account, and allows the immediate inclusion of large index difference levels as well as the two-dimensional continuously varying index profile function without the usual staircase approximation. As an example, dispersion characteristics are calculated for structures suitable for millimeter-wave and optical integrated circuits, such as channel waveguides with refractive index variations having stepped, linear, Gaussian, and exponential function profiles. The theory is verified by comparison with results available from other rigorous methods View full abstract»

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  • Microwave radiometric imaging at 3 GHz for the exploration of breast tumors

    Publication Year: 1990 , Page(s): 791 - 793
    Cited by:  Papers (27)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    A process of microwave radiometric imaging at 3 GHz permits the mapping of radiometric intensities on a square area about half a decimeter on a side. These data, translated in terms of a colored image, point out the existence of lateral temperature gradients in tissues. This system was initially used for examining large breast tumors; at present, it is also used for detecting smaller, impalpable tumors. The rules for characterizing benignancy or malignancy of small tumors which appear in a mammographic examination (X-rays) are defined. The definition of an appropriate parameter, deduced from this image processing, makes it possible to indicate benignancy or malignancy. In experiments conducted on 18 patients, all the malignant lesions had a radiometric ratio greater than 65%, while benign lesions were below 55%. However, a zone of uncertainty (between 55% and 70%) exists where it is wise not to assert malignancy or benignancy View full abstract»

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  • S matrix of slot-coupled H-plane tee junction using rectangular waveguides

    Publication Year: 1990 , Page(s): 779 - 781
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    Complex scattering matrix parameters of a slot-coupled, waveguide tee junction are determined using a moment method of analysis with entire orthogonal basis functions and a rigorous analysis of the effect of wall thickness. The variations of the equivalent network parameter, coupling, and return loss with frequency are evaluated, and the results are compared with experimental data. The unitary property of the S matrix is verified. The dependence of coupling on slot length, slot width, and thickness is presented View full abstract»

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  • Modeling of asymmetric and offset gaps in shielded microstrips and slotlines

    Publication Year: 1990 , Page(s): 818 - 822
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    A generalized model for characterizing the frequency-dependent properties of general symmetric, asymmetric, and offset gaps in microstrips and slotlines on a single-layer or multilayer dielectric medium is presented. The transverse resonance technique is applied in the spectral domain to extract the equivalent circuit model parameters of the discontinuities. This technique incorporates the end effect of the discontinuity by a compatible choice of basis functions View full abstract»

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  • Even-mode characteristics of the bilateral slotline

    Publication Year: 1990 , Page(s): 760 - 765
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (424 KB)  

    Transmission line data for the even-mode characteristics of a bilateral slotline (double-sided slotline) are presented. The slotline is analyzed by the spectral Galerkin method, and results are presented for the slot wavelength and characteristic impedance for substrates having εr=2.22, 3.5, 6.0, 9.8, and 12.8. The results are presented for 0.01⩽√εr-1d0⩽0.25, where 2d is the substrate thickness and εr its dielectric constant View full abstract»

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  • Reflection and transmission coefficients of rectangular dielectric waveguide discontinuity with an air gap

    Publication Year: 1990 , Page(s): 797 - 799
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (196 KB)  

    Reflection, transmission, and radiation characteristics of rectangular dielectric waveguide discontinuities with an air gap are analyzed. A transverse displacement with the air gap is also treated. The characteristics of this discontinuity have never been analyzed with a conventional slab model. In this analysis, a two-dimensional Fourier transformation and orthogonal relations between guided and radiation modes are utilized. Calculations and experimental results in X-band are compared, and good agreement is found. To discuss the numerical results, the principle of energy conservation is introduced. The discrepancy between the results and this principle is less than 0.0003 View full abstract»

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  • De-embedding and unterminating microwave fixtures with nonlinear least squares

    Publication Year: 1990 , Page(s): 787 - 791
    Cited by:  Papers (18)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (460 KB)  

    A general method of characterizing microwave test fixtures for the purpose of determining the parameters of devices embedded in the fixture is discussed. The technique was used to investigate deembedding under the assumptions that all measurement errors are random and normally distributed and that the standards are distributed uniformly around the Smith chart. It was shown that for any given number of standards, the greatest accuracy under these assumptions is achieved by utilizing a large set of known reflective loads. When the propagation constant and the reflection coefficients of the standards are not known, then equal numbers of thru lines and reflective loads give the highest accuracy, although not as high as when the propagation constant and reflection coefficients are known. The accuracy of the technique was studied and compared with that of the common open-short-load (OSL) and thru-reflect-line methods. The OSL technique was found to be considerably less accurate than using sets of offset reflective loads View full abstract»

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  • Analysis of transmission line structures using a new image-mode Green's function

    Publication Year: 1990 , Page(s): 782 - 785
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    A hybrid image-mode-moment method for the quasi-transverse-electromagnetic (quasi-TEM) analysis of transmission lines of arbitrary cross section and number, suspended between infinite parallel ground planes is discussed. This method systematically combines, in a single formulation, the conventional moment method with a new image-mode Green's function. The moment method is used to model the interaction between transmission lines, and the new image-mode method is used to furnish the Green's function of the parallel plates. Several configurations are studied and compared, where possible, with work given in the references View full abstract»

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  • Resonant frequency of cylindrical dielectric resonator placed in an MIC environment

    Publication Year: 1990 , Page(s): 802 - 804
    Cited by:  Papers (12)  |  Patents (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    An effective dielectric constant technique to determine the resonant frequency of the TE01δ mode of a cylindrical dielectric resonator placed in a microwave integrated circuit (MIC) environment is discussed. An expression for the dielectric constant εeff which makes it possible to obtain results that compare favorably with rigorous methods is given. Experimental results demonstrating the method's validity are also reported. For a given resonant frequency, closed-form expressions for computing the height of the resonator are given View full abstract»

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  • A local mesh refinement algorithm for the time domain-finite difference method using Maxwell's curl equations

    Publication Year: 1990 , Page(s): 812 - 815
    Cited by:  Papers (47)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    An efficient local mesh refinement algorithm, subdividing a computational domain to resolve fine dimensions in a time-domain-finite-difference (TD-FD) space-time grid structure, is discussed. At a discontinuous coarse-fine mesh interface, the boundary conditions for the tangential and normal field components are enforced for a smooth transition of highly nonuniform held quantities View full abstract»

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  • Perturbed-TEM analysis of transmission lines with imperfect conductors

    Publication Year: 1990 , Page(s): 754 - 759
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (456 KB)  

    A perturbed-transverse electromagnetic (TEM) approach to studying the detailed current distribution and the propagation constant of a multiconductor transmission line system with imperfect conductors is discussed. The perturbed fields are derived assuming that the fields outside the conductors are TEM waves of the corresponding lossless system and those inside the conductors satisfy the transverse magnetic (TM) modal equations. These fields are then inserted into a perturbational formula to obtain the propagation constant of the lossy system. The current distribution and the propagation constant (which clearly illustrates the loss mechanism due to the skin effect and the proximity effect) of a lossy two-wire system are presented as an example View full abstract»

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  • Full-wave analysis of an infinitely long magnetic surface wave transducer

    Publication Year: 1990 , Page(s): 730 - 738
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (708 KB)  

    A rigorous analysis of an infinitely long microstrip line embedded in a multilayer structure which includes a ferrite layer is presented. In certain frequency ranges, such a line launches magnetic surface waves in the ferrite layer and thus becomes a surface wave transducer. The analysis is a self-consistent, full-wave solution which rigorously includes the effect of radiating magnetic waves. By expanding the transducer currents in terms of both even and odd functions, it is shown that the principal current is not symmetrically distributed across the transducer width. The propagation constant of the transducer mode is complex and shows a large, imaginary part (attenuation) tied to the excitation of magnetostatic surface waves. In addition, the propagation constant remains complex even for frequencies above the magnetostatic surface wave bandwidth because the excitation of magnetic surface waves has complex propagation constants. Insertion loss measurements of a multilayer microstrip transducer are in reasonable agreement with the calculated attenuation View full abstract»

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  • Capacitance parameters of coupled elliptic microstrip disks in layered anisotropic media

    Publication Year: 1990 , Page(s): 794 - 796
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    An algorithm which calculates the modal capacitances and the gap capacitance of coupled microstrip elliptic disks embedded in layered media with dielectric anisotropy is discussed. The capacitance parameters determined are useful in accounting for coupling effects in the design of interacting lumped microstrip components of elliptic shape View full abstract»

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  • Electromagnetic modeling of waveguides involving finite-size dielectric regions

    Publication Year: 1990 , Page(s): 807 - 812
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    A moment method for handling arbitrarily shaped 2-D and 3-D waveguides that involve either conductors, finite-size dielectric regions, or both is presented. A procedure for modeling the dielectric allows 2-D rooftop functions to represent both the 3-D polarization current in the dielectric and the surface current on the conductors, and precludes the presence of fictitious charge within the dielectric. Examples include coaxial, microstrip, and dielectric waveguides. Numerical convergence, consistency with physical principles, and agreement with the literature are demonstrated View full abstract»

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  • The design of an ultra-broad-band 3 dB coupler in dielectric waveguide

    Publication Year: 1990 , Page(s): 785 - 787
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    A structure of embedding dielectric waveguide coupler that offers advantages such as very flat frequency response over 50% bandwidth, simple construction, and good repeatability is described. A theoretical analysis by superpositioning normal modes is presented. Experimental results at the 4-mm wave band showing agreement with theoretical calculations are given View full abstract»

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  • Wide-band ground-plane DC block and bias feed

    Publication Year: 1990 , Page(s): 805 - 806
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (176 KB)  

    The realization of a wideband, ground-plane DC block and bias feed for microstrip transmission lines operating in Ka-band, 26.5-40.0 GHz, is described. The waveguide-to-microstrip fixture and transition used for testing are described. Analysis of the ground-plane bias gap structure is provided. A few possible applications are discussed View full abstract»

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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..

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