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Microwave Theory and Techniques, IEEE Transactions on

Issue 7  Part 1 • Date July 1996

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Displaying Results 1 - 25 of 34
  • Comments on "Sensitivity analysis of lossy coupled transmission lines" [with reply]

    Page(s): 1187 - 1188
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (187 KB)  

    For the original article see ibid., vol. 39, no. 12, p. 2089-2099 (1991). In the aforementioned paper, a good agreement between the numerical inversion of Laplace transform (NILT) and HSPICE is presented for the transient response of a transmission line system with lumped terminal and interconnecting networks. Here Sakagami provides some comments on the derived transient response. In reply the authors clarify several points and give a summary of some results obtained in a numerical verification. View full abstract»

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  • Comments on "Measurement of the microwave conductivity of a polymeric material with potential applications in absorbers and shielding"

    Page(s): 1188 - 1189
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (206 KB)  

    For original paper see K.Naishadham and P.K.Kadaba, ibid., vol.39, pp.1158-64 (1991). Naishadham and Kadaba demonstrated the utilization of polyacetylene and PBT conductive polymers as single-layer, double-layer electric Salisbury screens and EMI shields. In this article the authors comment on some inconsistencies that were found between the calculated results and the assumptions stated. A reply by Naishadham and Kadaba is included. View full abstract»

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  • Reduced invasiveness of noncontact electrooptic probes in millimeter-wave optoelectronic characterization

    Page(s): 1155 - 1157
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    We report time-resolved measurements of the invasiveness of LiTaO 3 external probes in millimeter-wave electrooptic sampling. Using external probe tips at varying distances from a coplanar stripline, we show that invasiveness can be reduced in a noncontact configuration at the expense of measurement sensitivity. In the contact configuration, the risetime can be significantly lengthened by dispersion and signal reflection caused by the probe tip View full abstract»

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  • Development of accurate on-wafer, cryogenic characterization techniques

    Page(s): 1178 - 1183
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    Significant advances in the development of high electron mobility field-effect transistors (HEMT's) have resulted in cryogenic, low-noise amplifiers (LNA's) whose noise temperatures are within an order of magnitude of the quantum noise limit (hν/k). Further advances in HEMT technology at cryogenic temperatures may eventually lead to the replacement of maser and superconducting-insulator-superconducting (SIS) front-ends in the 1-100 GHz frequency band. Key to identification of the best HEMT's and optimization of cryogenic LNA's is accurate and repeatable device measurements at cryogenic temperatures. A cryogenic on-wafer noise and scattering parameter measurement system has been developed to provide a systematic investigation of HEMT noise characteristics. In addition, an improved parameter extraction technique has been developed to help understand the relationship between device structure and LNA performance View full abstract»

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  • Whispering-gallery modes and permeability tensor measurements in magnetized ferrite resonators

    Page(s): 1097 - 1102
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (932 KB)  

    Whispering-gallery modes in axially magnetized ferrite disk samples have been studied using rigorous Rayleigh-Ritz and finite-element analyses. The influence of radial magnetization on the resonant frequencies of both WGE and WGH modes was investigated, both theoretically and experimentally. Permeability tensor components of biased ferrites were determined from measurements of the resonant frequencies of the WGHn00 and the WGEn00 mode families View full abstract»

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  • Modal circuit decomposition of lossy multiconductor transmission lines

    Page(s): 1046 - 1056
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (820 KB)  

    General multi-conductor transmission lines are investigated using modal analysis. This is performed by finding the solution to the telegrapher's equations for general impedance and admittance per unit length matrices Z and Y, respectively, and obtaining the transmission matrix in terms of Z and Y. Hence, the modal circuit is sought, resulting in a cascade of two n-port ideal transformers and n uncoupled transmission lines. A set of necessary and sufficient conditions are established and a construction method is given if the conditions are satisfied. It is shown that the modal circuit will always exist for general homogeneous constant parameters and for the nonhomogeneous case under the quasi-TEM assumption the existence depends on the geometry. The modal circuit is extended for frequency dependent parameters and a set of sufficient conditions are given View full abstract»

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  • High-efficiency InP-based DHBT active frequency multipliers for wireless communications

    Page(s): 1165 - 1167
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (268 KB)  

    We present, for the first time, the performance of AlInAs/GaInAs/InP double heterostructure bipolar transistors (DHBT's) as active frequency multipliers at frequencies of relevance to Wireless Communications applications. In particular, we present results comparing the performance of X6 (127→762 MHz) and X4 (762.5→3050.0 MHz) InP- and Si-based (NEC2107) multiplier circuits. A well-known multiplier circuit topology has been chosen as a vehicle, so that we can focus on active device comparison. The X6 InP-based multiplier exhibits output power and efficiency of +6 dBm and 11%, respectively, compared to +7.2 dBm and 4.8% of the Si-based circuit. The X4 InP-based multiplier exhibits output power and efficiency of +3.74 dBm and 8%, respectively, compared to -6.1 dBm and 0.4% of the Si-based circuit. The superior electronic properties of InP-DHBT's enable high-conversion gain/highly DC-efficient multipliers, however, their nonexponential IC-V BE characteristic limits the maximum obtainable conversion gain at high-order frequency multiplication View full abstract»

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  • Analysis of microstrip discontinuities using the spatial network method with absorbing boundary conditions

    Page(s): 1157 - 1161
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (392 KB)  

    In this paper it is shown that spatial network method (SNM) can be formally derived as a finite differencing scheme, which ensures that the necessary stability and convergence conditions are met. For the first time, Mur and Higdon second-order absorbing boundary conditions (ABC's) have been used in conjunction with SNM. It has been found that the Higdon second-order ABC's perform better than the Mur algorithm for guided wave problems with inhomogeneous substrates. Finally, it is shown that SNM can successfully be employed for the analysis of planar and three-dimensional (3-D) microstrip discontinuities in open or shielded environments View full abstract»

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  • Analysis of cylindrical transmission lines with the method of lines

    Page(s): 993 - 999
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    Cylindrical transmission lines are important for a variety of applications. To calculate their propagation characteristics, the method of lines in cylindrical coordinates has been adopted. By discretizing the angular space direction with radial lines, the two-dimensional (2-D) Helmholtz equation reduces to a set of ordinary one-dimensional (1-D) differential equations, which can be solved analytically in radial direction after an orthogonal transformation. To improve the accuracy of the cylindrical method of lines from second-order to fourth-order, neighboring lines are used to eliminate second-order discretization errors not only in the Helmholtz equation but also in the continuity equation and in the edge condition. The method is suitable for the analysis of asymmetric cylindrical homogeneous and inhomogeneous guided wave structures View full abstract»

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  • BiCG-FFT T-Matrix method for solving for the scattering solution from inhomogeneous bodies

    Page(s): 1150 - 1155
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    A BiCG-FFT T-Matrix algorithm is proposed to efficiently solve three-dimensional scattering problems of inhomogeneous bodies. The memory storage is of O(N) (N is the number of unknowns) and each iteration in BiCG requires O(N log N) operations. A good agreement between the numerical and exact solutions is observed. The convergence rate for lossless and lossy bodies of various sizes are shown. It is also demonstrated that the matrix condition number for fine grids is the same as that for coarse grids View full abstract»

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  • Radial mode matching analysis of ridged circular waveguides

    Page(s): 1183 - 1186
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    In this paper a radial mode matching analysis is presented to calculate rigorously the TE and TM mode propagation in single- double-, triple-, and quadruple-ridged circular waveguide structures. The ridges have been cut radially in all the cases. Results are presented for variations of the ridge depth and ridge thickness and are compared to results from finite element analysis. Furthermore, for the first time, the characteristic impedance of the double and quadruple-ridged circular waveguides have been calculated using the power-voltage definition View full abstract»

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  • An integrated transition of microstrip to nonradiative dielectric waveguide for microwave and millimeter-wave circuits

    Page(s): 1091 - 1096
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    Effective interconnects between two or more different waveguides are essential for using hybrid architecture of circuits as well as multipurpose instrumentation and measurements at microwave and millimeter-wave frequencies. In this paper, a new transition of microstrip line to nonradiative dielectric (NRD) guide is reported that makes it possible to design a class of compact NRD waveguide circuits directly integrated with planar-microstrip-based devices and components. A small aperture coupling theory is developed and effectively applied to model the proposed structure. It is found that theoretical results are in good agreement with experiments. The proposed transition promises to be instrumental in integrating planar microstrip devices and components with NRD guide circuits View full abstract»

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  • A wideband waveguide transition design with modified dielectric transformer using edge-based tetrahedral finite-element analysis

    Page(s): 1024 - 1031
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (756 KB)  

    A waveguide transition analysis approach has been established to deal with arbitrary shaped three-dimensional (3-D) waveguide discontinuity problems, by hybridizing the edge-based tetrahedral finite-element method for the junction region and the analytic modal expansion technique for the waveguide region. Several unique features have been imbedded in the analysis, including a variational formula for the scattering coefficients, a modified Delaunay triangulation for the mesh generation, and a frontal solution technique for the sparse matrix solution. As a result, the analysis is verified to be accurate, versatile, and efficient through extensive comparisons with the theoretical and measurement data in the available literature. The approach is then applied to design a rectangular to dielectric-filled circular waveguide transition with less than -20 dB return loss over a 40% bandwidth by using a suitable modified dielectric rod transformer View full abstract»

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  • A channelized-limiter approach to receiver front-end protection

    Page(s): 1125 - 1129
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    The receiver protection scheme being presented relies on frequency channelization of incident signals to accomplish +amplitude limiting on a frequency-selective, self-induced, instantaneous basis. A demultiplexer separates signals into contiguous subbands for parallel processing, after which they are reunited by a multiplexer to yield a signal composite of original bandwidth. The scheme's attractiveness lies in its ability to combine the advantages of fast response, broadband, passive limiters with the benefits of narrowband signal rejection techniques that employ frequency-tunable or switched notch filters. The concept is demonstrated with an experimental five-channel modified-logarithmic-periodic limiter prototype circuit, configured as a 7.5- to 12.5-GHz channelized self-limiting amplifier. The measured results confirm the circuit's transparency to small-amplitude signals and illustrate its effectiveness in confining large-signal effects, such as gain compression and intermodulation products, to narrow frequency intervals View full abstract»

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  • Analysis of slot-coupled double-sided cylindrical microstrip lines

    Page(s): 1167 - 1170
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    The problem of double-sided cylindrical microstrip lines coupled through a rectangular slot in the common cylindrical ground plane is studied using the reciprocity theorem and a moment-method calculation. Theoretical results of the S-parameters for the slot-coupled cylindrical microstrip lines are calculated and analyzed. Experiments are also conducted to verify the theoretical results View full abstract»

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  • Spectral domain analysis of single and coupled microstrip open discontinuities with anisotropic substrates

    Page(s): 1174 - 1178
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    The normalized input admittance for single and coupled microstrip open discontinuities with anisotropic substrates are obtained using a full-wave analysis. Problem is formulated in terms of the field Green's function in the spectral domain. Numerical results are found to be in good agreement with the published theoretical and experimental results for microstrip open discontinuities with anisotropic/isotropic substrates View full abstract»

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  • Thermal noise in lossy waveguides

    Page(s): 1067 - 1073
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    This work rigorously treats thermal electromagnetic noise in lossy waveguides and develops explicit modal equivalent-circuit representations for the noise generated by arbitrary passive networks embedded in them. The results show that the formulations in common use are limited to lossless transmission media View full abstract»

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  • Design and analysis of transitions from rectangular waveguide to layered ridge dielectric waveguide

    Page(s): 1032 - 1040
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    Transitions from rectangular waveguide to layered ridge dielectric waveguide are studied both experimentally and theoretically. In addition, a design procedure is given for each transition. The analysis and design procedures are valid for transitions between rectangular waveguide and other open dielectric waveguides such as image guide, insulated image guide, dielectric ridge guide, and inverted strip dielectric waveguide. It is shown that for small dielectric waveguides such as layered ridge dielectric waveguide, a transition which is comprised of a tapered ridge waveguide reduces the radiation loss by at least 1 dB View full abstract»

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  • Some considerations on the accuracy of the nonuniform FDTD method and its application to waveguide analysis when combined with the perfectly matched layer technique

    Page(s): 1115 - 1124
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (764 KB)  

    The accuracy of the finite-difference time-domain (FDTD) technique is measured with respect to the mesh's cell dimensions. The accuracy of the FDTD technique is investigated for those applications that demand the use of nonuniform meshes. The results of simulations suggest that second-order accuracy can be achieved. These simulations are carried out using different boundary conditions. It is observed that the choice of boundary conditions plays a large role in the accuracy that is achieved with the FDTD method. The perfectly matched layer (PML) technique is found to be well suited to waveguide analysis because of its wide bandwidth, and the ease with which it can be implemented with a nonuniform mesh. We apply the nonuniform FDTD method, in combination with the PML technique, to analyze a narrow iris in waveguide View full abstract»

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  • Wideband modeling of arbitrarily shaped H-plane waveguide components by the “boundary integral-resonant mode expansion method”

    Page(s): 1057 - 1066
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (876 KB)  

    The paper describes a very fast and flexible algorithm for the wideband modeling of arbitrarily shaped H-plane waveguide components. The algorithm is based on the evaluation of the poles and the residues of the Y-parameters by the “boundary integral-resonant mode expansion method.” It also permits the fast evaluation of the effect of a deformation on the frequency response, a feature very useful either for optimization or for setting the mechanical tolerances. Some examples demonstrate the efficiency, flexibility, and reliability of the method. They show that the frequency response of complicated structures, such as multicavity filters, can be calculated in times of the order of one minute (or less) on ordinary workstations View full abstract»

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  • Automatic derivation of equivalent circuits for general microstrip interconnection discontinuities

    Page(s): 1010 - 1016
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    The techniques presented in this paper allow one to automatically derive equivalent LC-networks for general lossless microstrip interconnection discontinuities. The method is completely based on physical considerations and does not involve any fitting procedure. The technique is quite fast, and the resulting networks are closely related to the physical structure. Due to the fact that we only use lumped passive circuit elements, the structures under consideration are assumed to be small as compared to the electrical wavelength. The extension of our technique to multilayered planar structures with vias is possible. It is also possible to deal with lossy dielectrics, finite conductivity metallizations, and radiation. The main application area of our technique is the modeling of interconnection discontinuities in high speed digital circuits View full abstract»

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  • Digitizing multichannel video signals for lightwave transmission

    Page(s): 1041 - 1045
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    This paper presents a new approach to the design of lightwave multichannel CATV transmission systems using broadband digital coding to convert an all-analog multiplexed video signal to a string of pulses suitable for digital transmission. Four broadband coding methods have been discussed and compared, which are: uniform and optimal companding PCM, as well as uniform and adaptive DM. The principle advantages of this approach include the benefits obtainable from digital transmission and also direct compatibility with current CATV networks. CNR limits have been investigated for all of these methods View full abstract»

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  • Eigenmodes in a toroidal cavity of elliptic cross section

    Page(s): 1147 - 1150
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    The axisymmetric electromagnetic eigenmodes of a toroidal resonator with elliptic cross section are analyzed by solving the basic equations up to the lowest order in inverse aspect ratio. The effects of toroidicity and ellipticity of the cross section are quite significant for both TE and TM modes View full abstract»

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  • Nondestructive measurements of complex tensor permittivity of anisotropic materials using a waveguide probe system

    Page(s): 1081 - 1090
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (792 KB)  

    A nondestructive measurement of electromagnetic (EM) properties of anisotropic materials using an open-ended waveguide probe has been conducted. Two coupled electric field integral equations (EFIE's) for the aperture electric field are derived and solved numerically by employing the method of moments (MoM). After the determination of the aperture electric field, the reflection coefficient of the incident wave can be expressed in terms of the EM parameters of the material. Then, the EM parameters of the material layer can be inversely determined if the reflection coefficient of the incident wave is experimentally measured. A series of experiments has been conducted using the waveguide probe system constructed at MSU electromagnetics laboratory. The inverse results of the EM properties of various materials are presented. Finally, the effects of material parameters on the probe input admittance that cause problems in the measurement are analyzed 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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