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Microwave Theory and Techniques, IEEE Transactions on

Issue 7  Part 1-2 • Date July 1994

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Displaying Results 1 - 25 of 50
  • Evaluation of quasi-static matrix parameters for multiconductor transmission lines using Galerkin's method

    Publication Year: 1994 , Page(s): 1223 - 1228
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (646 KB)  

    Quasi-static matrix parameters for multiconductor transmission lines are numerically evaluated by solving a set of integral equations for the bound charges using Galerkin's technique, with a piecewise constant approximation for the charge distribution. Several hints are given as how to improve the efficiency and accuracy of computations.<> View full abstract»

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  • Comments on "Useful Bessel function identities and integrals" [with reply]

    Publication Year: 1994 , Page(s): 1283 - 1284
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (95 KB)  

    The original paper [see ibid., vol, 41, p 1468-71, 1993] is claimed to contain nothing new either in substance or in application. It would appear that one of the reasons for the publication is that the integrals derived therein are not found in common references. Furthermore, the proof given in the paper is in the nature of a verification and hence hinges upon knowing the correct answers beforehand. It is not difficult to establish direct proofs. The original authors give their reply to these comments.<> View full abstract»

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  • Rigorous solution of mode spectra for shielded multilayer microstrip lines

    Publication Year: 1994 , Page(s): 1213 - 1222
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (804 KB)  

    Based on the equivalent transmission line concept, a simplified method has been developed to derive the dyadic Green's functions and field expansion coefficients for multilayer structures. An improved formulation of the singular integral equation method is presented for shielded multilayer microstrip lines. A systematic method for analytically calculating the final characteristic matrix to any order is also proposed. The developed numerical technique leads to an accurate and efficient determination of both propagation constants and field distributions for a large number of eigenmodes. For instance, 100 modes can easily be computed in reasonable CPU time View full abstract»

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  • FET model parameter extraction based on optimization with multiplane data-fitting and bidirectional search-a new concept

    Publication Year: 1994 , Page(s): 1114 - 1121
    Cited by:  Papers (32)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    A new optimization formulation is presented for efficient FET model parameter extraction, in which data-fitting is carried out in multi reference planes instead of only one, and the objective function is minimized by a bidirectional search technique. As an example of application, all parameters of a commonly used 15-element small-signal FET equivalent circuit model are clearly identified from only one set of measured S-parameters. A self-consistent generation of starting values can be involved regarding the FET in the passive pinch-off operating mode. Moreover, applying multi-bias data-fitting, which is performed without increasing the number of ordinary optimization variables, yields a robust determination of both the overall bias-independent parasitics and the bias-dependent intrinsic elements. For demonstration results are presented for a 0.5-μm MESFET View full abstract»

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  • A simple convolution procedure for calculating currents induced in the human body for exposure to electromagnetic pulses

    Publication Year: 1994 , Page(s): 1172 - 1175
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (364 KB)  

    The finite-difference time-domain (FDTD) and frequency dependent finite difference time-domain (FD)2TD methods have been previously used to calculate internal electric (E) fields and induced currents for exposure of the anatomically based model of the human body to electromagnetic pulses (EMPs) and continuous wave (CW) sinusoids. The limitation of these methods is that a complete, computer resource intensive, simulation must be done for each different waveform of interest. The authors describe a simple and efficient technique based on convolution theory which provides the response of the body to any incident waveform (EMP or CW) from a single simulation with an incident impulse waveform. This allows the impulse response to be stored, and the response of the body to any desired waveform to be efficiently computed on a small computer or PC View full abstract»

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  • Modeling the GaAs MESFET's response to modulated light at radio and microwave frequencies

    Publication Year: 1994 , Page(s): 1122 - 1130
    Cited by:  Papers (16)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (784 KB)  

    In recent years, the usefulness of the MESFET as an optically sensitive microwave element on MMIC's has generated much interest. A theoretical model for the device under steady illumination has been developed previously by the authors. This paper presents an extension of that model to include sinusoidally modulated illumination up to the microwave range. The dependence of the response on the bias conditions, the wavelength intensity and modulation frequency of the optical input, and the particulars of device structure are incorporated in the model. The importance of the internal photovoltaic effect, not properly accounted for in previous works, is emphasized. The theoretical model is validated by experimental results View full abstract»

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  • Simple CAD procedure for microwave filters and multiplexers

    Publication Year: 1994 , Page(s): 1347 - 1352
    Cited by:  Papers (41)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    The design of microwave filters and multiplexers requires a common step before actual hardware implementation, namely, the identification of a number of specific ideal electrical components with actual waveguide discontinuities. In the past, this step was accomplished semi-analytically using approximate single-mode discontinuity models. The complete filter or multiplexer could then be assembled, but additional final tuning or optimization with a large number of parameters was generally required. In this paper, we propose an alternative technique for the design of microwave filters or multiplexers that directly uses a full-wave electromagnetic simulator and that effectively decomposes the complex design task into a series of simple sub-tasks with clearly identified objectives. The procedure described only involves a limited number of actual physical parameters at each step so that it is computationally very efficient and rapidly convergent View full abstract»

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  • Electrodynamic theory of finite magnetostatic waveguides

    Publication Year: 1994 , Page(s): 1238 - 1245
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (724 KB)  

    In this paper the electrodynamic theory of arbitrary magnetostatic waveguide structure (WS) based on a sequence approach method is established. To calculate a wave number, a magnetic scalar potential distribution, an electric field and a power frequency dependence of arbitrary type WS's eigenmodes a new version of finite difference method based on integro interpolated approach is developed. To show the availability of this technique four types of the MSW WS are studied: the first is a narrow waveguide being analyzed taking into account the two-dimensional inhomogeneity of its internal demagnetized field which follows from the rigorous solution of respective nonlinear boundary task to calculate the dc magnetic field distribution in the ferrite slab of finite sizes. The second and third WS are the two ferrite slabs of a finite width connected guides and the last is the finite width double-layer of different saturation magnetization nonreciprocal WS. The results of the computing method validity verification are discussed in the paper too. It concludes the developed method to be powerful and to be used to analyze electrodynamic properties of MSW WS's of different types View full abstract»

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  • Transmission properties of metal-semiconductor-relaxor microstrip lines

    Publication Year: 1994 , Page(s): 1176 - 1182
    Cited by:  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    The transmission characteristics of multilayer ferrite-high-K microstrip lines have been calculated by means of the parallel-plate waveguide approximation. The relaxation behavior of the dielectric permittivity and permeability have been taken into account by using the Debye and the Maxwell-Wagner relaxation models. The results demonstrate that these lines can be used as very small size delay lines and low-pass filters that can be tuned by adjusting the layer thickness ratio, the resistivity of the semiconductor layer, and the difference between the permittivity-permeability product of each layer View full abstract»

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  • Hybrid inductor modeling for successful filter design

    Publication Year: 1994 , Page(s): 1426 - 1429
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    A method for deriving accurate L-band inductor models using I-port fixtured S-parameter measurements is presented, along with examples of successful filter designs using the models. Models were developed for a number of surface-mount and leaded devices with values ranging from 4.7 nH to 470 nH. The devices were measured in a coaxial test fixture on an HP8510B network analyzer, with fixture de-embedding performed using CAD software. The models are seen to fit measured data over a broadband, from low RF through resonance. To further validate the models, several filter circuits were developed and fabricated. The results of 5th- and 9th-order lowpass filter designs are presented here. The 9th-order filter was optimized for the desired performance using the parasitic inductor models. Measurements confirm that the use of the models led to a successful design on the “first pass.” Finally, simulations show that this success would not have been achieved without the developed inductor models View full abstract»

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  • GaAs MESFET active resonant circuit for microwave filter applications

    Publication Year: 1994 , Page(s): 1419 - 1423
    Cited by:  Papers (8)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    Inverting and noninverting active integrator circuits are compensated for the effect of finite output conductance of the GaAs MESFET by the addition of capacitors and then used to realize an active tuned circuit resonating at 1.5 GHz with fully controllable Q-factor. The active tuned circuit is promising for implementing high-order IF filters at low-microwave frequencies View full abstract»

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  • On the dispersion in TLM and FDTD

    Publication Year: 1994 , Page(s): 1275 - 1279
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    The dispersion relations of a two-dimensional TLM mesh and a three-dimensional TLM mesh with condensed symmetric nodes are calculated. For the calculation of the TLM dispersion relations, we use a generalized method which can be applied to any TLM node described by square scattering and propagation matrices of equal dimension. Introducing the FDTD Hilbert space representation, it is shown that the method is closely related to the method of calculating FDTD dispersion relations View full abstract»

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  • Analysis of radiation from an open-ended coaxial line into stratified dielectrics

    Publication Year: 1994 , Page(s): 1261 - 1267
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (532 KB)  

    Radiation from an open-ended coaxial transmission line into an N-layer dielectric medium is studied in application to nondestructive evaluation of materials. Explicit formulations for two cases of layered media, one terminated into an infinite half-space and the other into a conducting sheet are addressed in general form. In the theoretical derivations it is assumed that only the fundamental TEM mode propagates inside the coaxial line. The terminating admittance of the line is then formulated using the continuity of the power flow across the aperture. The admittance expressions for specific cases of two-layer dielectric composite with generally lossy dielectric properties, and a two-layer composite backed by a conducting sheet are presented and inspected explicitly. The numerical results of the aperture admittance formulation are discussed and compared with the available infinite half-space model which had been experimentally verified View full abstract»

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  • Design of mobile phone IIDT-type SAW filters with block-like distribution of transducers

    Publication Year: 1994 , Page(s): 1380 - 1386
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (676 KB)  

    Wide band low-loss SAW filters employing interdigitated interdigital transducers (IIDT's) and suitable for cellular radio applications are presented. After an investigation of the many design parameters that have to be taken into account, a new block-like distribution of transducers within the IIDT structure is studied in detail. This distribution leads to almost identical impedances at the filter input and output. An automatic optimization algorithm is also described. In particular, the finger numbers and the withdrawal weighting functions employed to increase the stopband rejection have been optimized by this algorithm. Filters fabricated on 36° rot Y, X-LiTaO3 exhibit fractional bandwidths of up to 5.2% with passband ripples smaller than 1 dB at a center frequency of 500 MHz. The minimum insertion loss and the stopband rejection obtained were 1.8 and 23 dB, respectively View full abstract»

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  • A compact, high power notch filter with adjustable F0 and bandwidth

    Publication Year: 1994 , Page(s): 1397 - 1403
    Cited by:  Papers (6)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (664 KB)  

    The network described is a notch filter, synthesized as a capacitively-coupled short circuited shunt stub design. A well-known equivalence between open circuited, quarter wavelength high-impedance stubs, and capacitively coupled short-circuited stubs of lower impedance, is used iteratively to achieve a design with some innovative features: The shunt stubs are all the same impedance; typically; 50 Ω. The series 90 degree coupling lines are also the same impedance (again typically 50 Ω). Dimensions and components may thus be easily selected for high-power and low-loss operation. The coupling capacitors (which are in series with the stubs) are adjustable without compromising Q. Re-entrant stubs are used which allow a mixed lumped-distributed stub response and easy adjustment of stub lengths. A rugged coaxial construction is adopted with nothing cantilevered or unsupported. These features result in a design which is quite compact, tunable over a wide range of center frequencies, allows for adjustable bandwidth and thus selectivity, while intrinsically exhibiting high-power capability, low passband loss, and suitability for operation in demanding environments View full abstract»

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  • Scattering matrix of cylindrical posts centered on the walls of rectangular waveguides

    Publication Year: 1994 , Page(s): 1198 - 1206
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    A model, based on the moment method, is developed for the determination of the scattering matrix of cylindrical metal posts of variable height centered on two or four walls of a rectangular waveguide. The case of two posts, on the horizontal or on the vertical walls of the waveguide, is treated initially. The equivalence principle, dyadic Green's functions and the moment method are applied to the construction of a rigorous solution of the problem. Posts on the four walls of the waveguide are considered subsequently. In this case an approximation is introduced, by neglecting the influence of the fields scattered by the horizontal posts on the currents induced on the vertical ones, which is justified due to the small magnitude of such fields. It results a rapid, stable and accurate algorithm of calculus, the accuracy being corroborated by experimental data View full abstract»

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  • Multilayer suspended stripline and coplanar line filters

    Publication Year: 1994 , Page(s): 1403 - 1407
    Cited by:  Papers (26)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    Using metallization patterns on both sides of a suspended stripline substrate or adding an additional dielectric and conductor layer to coplanar line circuits, additional degrees of freedom arise for filter design like an extended range of impedances, tightly coupled line structures or increased end coupling between lines of different metallization layers. In this way, very compact filter circuits with improved performances may be realized as it is shown for different types of filters using this technique, even including active elements to realize strongly frequency selective amplifiers or active filters View full abstract»

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  • Frequency-independent equivalent circuit model for microstrip open-end and gap discontinuities

    Publication Year: 1994 , Page(s): 1268 - 1272
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (416 KB)  

    The development of user friendly software for microwave integrated circuits will become possible with the adoption of lumped equivalent circuits for interconnect discontinuities. Frequency independent equivalent lumped circuit models are proposed in this paper, wherein resistors are introduced to account for radiation and surface wave losses at microstrip discontinuities. Simple algebraic expressions are obtained for the elements of lumped equivalent circuits for the microstrip open-end and gap discontinuities. These expressions are highly accurate as they are obtained from the full-wave solution in conjunction with physical interpretation and curve fitting techniques. These equivalent circuits include resistor, inductor, and capacitor elements View full abstract»

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  • A broadband free-space millimeter-wave vector transmission measurement system

    Publication Year: 1994 , Page(s): 1131 - 1139
    Cited by:  Papers (14)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB)  

    We report both broadband monolithic transmitter and receiver IC's for MM-wave electromagnetic measurements. The IC's use a nonlinear transmission line (NLTL) and a sampling circuit as a picosecond pulse generator and detector. The pulses are radiated and received by planar monolithic bow-tie antennas, collimated with silicon substrate lenses and off-axis parabolic reflectors. Through Fourier transformation of the received pulse, accurate 30-250 GHz free space gain-frequency and phase-frequency measurements are demonstrated. Systems design considerations are discussed, and a variety of MM-wave broadband transmission measurements are demonstrated View full abstract»

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  • Microstrip filter design using direct EM field simulation

    Publication Year: 1994 , Page(s): 1353 - 1359
    Cited by:  Papers (35)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (648 KB)  

    For the first time, we present minimax filter design with electromagnetic (EM) simulations driven directly by a gradient-based optimizer. Challenges of efficiency, discretization of geometrical dimensions, and continuity of optimization variables are overcome by a three-stage attack: 1) efficient on-line response interpolation with respect to geometrical dimensions of microstrip structures simulated with fixed grid sizes; 2) smooth and accurate gradient evaluation for use in conjunction with the proposed interpolation; and 3) storing the results of expensive EM simulations in a dynamically updated database. Simulation of a lowpass microstrip filter illustrates the conventional use of EM simulation for design validation. Design optimization of a double folded stub bandstop filter and of a millimeter-wave 26-40 GHz interdigital capacitor bandpass microstrip filter illustrates the new technique View full abstract»

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  • Scalar magnetostatic potential approach to the prediction of the excess inductance of grounded via's and via's through a hole in a ground plane

    Publication Year: 1994 , Page(s): 1229 - 1237
    Cited by:  Papers (17)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    A quasi-static method is described for calculating the excess inductance of via's. The considered via geometry contains connecting strips, pads on the via, and a finite ground plane thickness. An integral equation based on the scalar magnetic potential ψ is solved. The inductance is found by calculating the magnetic flux through a cut introduced to define ψ in an unequivocal way. The problem is generally solved for via through-holes; the grounded via-configuration is found as a limiting case. The influence of the geometric parameters on the via inductance is examined View full abstract»

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  • A 2-step waveguide E-plane filter design method using the semi-discrete finite element method

    Publication Year: 1994 , Page(s): 1407 - 1411
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    The semidiscrete finite element method is used to design rectangular waveguide E-plane filters over a wide range of band-widths. First, a single filter element is characterized over the frequency range of interest by extracting lumped element values from the full-wave solution. A filter is then designed and optimized using the k-parameter method in which only first-order mode interaction between elements is considered. The filter response is then further refined by optimizing the full-wave response of the entire filter. This numerical technique exhibits excellent numerical convergence, with accuracy better that one percent with only 30 finite element nodes. Two filters were designed and their responses measured to verify the accuracy of the numerical technique View full abstract»

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  • A new rigorous method for the determination of iris dimensions in dual-mode cavity filters

    Publication Year: 1994 , Page(s): 1314 - 1320
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    A variational method based on the mode expansion is used in order to determine the accurate physical dimensions of coupling irises in dual-mode cavity filters. By considering the concept of localized and accessible modes, a series of convergence tests are carried out in order to optimize the number and nature of modes which should be included in the numerical calculations. As a consequence, the size of matrices involved and the corresponding computation time are reduced dramatically. This approach, validated by corresponding experimental data, allows us to achieve a considerable reduction of the fabrication time of this type of filter. Actually, the filter can be tuned immediately without any correction of the calculated irises View full abstract»

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  • Linear fractional curve fitting for measurement of high Q factors

    Publication Year: 1994 , Page(s): 1149 - 1153
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    A procedure is described for a precision measurement of the unloaded Q factor and of the coupling coefficient for microwave resonators. The complex reflection coefficient data are processed by the linear fractional curve-fitting routine on a personal computer View full abstract»

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  • Computer-aided analysis and design of a planar multilayer Marchand balun

    Publication Year: 1994 , Page(s): 1429 - 1434
    Cited by:  Papers (19)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    Analytical expressions for the scattering (S) parameters for a planar multilayer Marchand balun, constructed of broadside-coupled microstriplines, are derived for the first time, based on the coupled-line quasi-TEM normal mode parameters. New design equations and a new design procedure for the balun based on the derived S-parameters and a circuit synthesis technique are presented. Calculated results for a GaAs microwave monolithic integrated circuit balun designed by this procedure are compared to a general full-wave planar analysis, and good performance and agreement are obtained View full abstract»

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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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