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Microwave Theory and Techniques, IEEE Transactions on

Issue 7 • Date Jul 1988

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Displaying Results 1 - 15 of 15
  • Expansions for the capacitance of the Bowman squares

    Publication Year: 1988 , Page(s): 1216 - 1219
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    Expansions are given for the capacitance per unit length for the geometry in which two infinite, square cylinders are placed concentric with each other and rotated so that the edges of the inner square are closest to the sides of the outer square View full abstract»

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  • Noise parameters of SIS mixers

    Publication Year: 1988 , Page(s): 1196 - 1206
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (988 KB)  

    It has been shown that low-noise receivers can be constructed at millimeter wavelengths by using mixers containing superconducting tunnel junctions as the nonlinear elements. This is possible because of both the low intrinsic noise of these devices and their potential for high conversion gain. Here, the quantum theory of mixing is used to derive the full-noise parameters and small-signal parameters of sinusoidally pumped SIS (superconductor-insulator-superconductor) junctions. These are then put into a form that allows the theory of two-port linear networks to be brought to bear, allowing calculation of such useful parameters as minimum noise temperature, optimum source impedance, available (or exchangeable) gain at minimum noise, and stability factor. These quantities are properties of the pumped junction that do not depend on the source or load impedance, but do depend on the terminations at the image and harmonic sideband frequencies. The harmonic sidebands are taken to be shorted, and the image termination dependence is studied. Numerical results are presented for both ideal (BSC theory) and practical (measured current-voltage characteristic) junctions. The noise parameters of the cascade connection of an SIS mixer and a (noisy) IF amplifier are considered, leading to a specification of the optimum coupling network between the two. It is noted that the SIS mixer is usually not unconditionally stable, but that oscillation can be avoided by careful design of the IF coupling network View full abstract»

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  • Power-bandwidth considerations in the design of MESFET distributed amplifiers

    Publication Year: 1988 , Page(s): 1117 - 1123
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    Quantitative procedures are given for the design of MESFET distributed amplifiers using series capacitors in the device gate circuits. It is shown that the choice of series capacitors allows the designer to trade gain for bandwidth while maintaining a given gain-bandwidth product. It is also shown that the input power capability can be increased by the use of series capacitors when the device pinch-off is the power-limiting factor. It is pointed out how the addition of series capacitors makes it possible to increase the gate periphery of an amplifier, which results in an increase in power-bandwidth product View full abstract»

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  • Finite-element formalism for nonlinear slab-guided waves

    Publication Year: 1988 , Page(s): 1207 - 1215
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    A unified computer-aided numerical approach, based on the finite-element method, is developed for analyzing optical waves guided by dielectric slab waveguiding structures with arbitrary nonlinear media. In the formulations, both TE and TM polarizations are considered. For the TM case, the biaxial nature of nonlinear refractive index is considered without any approximation. Numerical results are presented for nonlinear TE and TM waves propagating in symmetric slab waveguides. The dependence of dispersion relations on the refractive-index profile of the film is examined View full abstract»

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  • Attenuation measurement of very low loss dielectric waveguides by the cavity resonator method applicable in the millimeter/submillimeter wavelength range

    Publication Year: 1988 , Page(s): 1160 - 1166
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    A dielectric waveguide shorted at both ends was constructed as a cavity resonator. By measuring the Q of this cavity, one can determine the attenuation constant of this guided mode on this dielectric structure. The complex permittivity of the dielectric waveguide material can also be derived from the measurements. Measurements were made at Ka-band for dielectric waveguides constructed of nonpolar, low-loss polymers, such as Teflon, polypropylene, polyethylene, polystyrene, and rexolite View full abstract»

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  • Simple approximations for the longitudinal magnetic polarizabilities of some small apertures

    Publication Year: 1988 , Page(s): 1141 - 1144
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    Simple approximations are given for the longitudinal magnetic polarizabilities of some small apertures of various shapes, as functions of the aperture width to length ratios. The shapes considered are the rectangle, diamond, rounded end slot, and ellipse, of which only the last has an explicit solution View full abstract»

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  • Modal attenuation in multilayered coated waveguides

    Publication Year: 1988 , Page(s): 1167 - 1176
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (680 KB)  

    Propagation and attenuation constants of low-order normal modes in a circular waveguide lined with lossy coating layers are calculated using a generalized dispersion equation. It is found that the use of multilayered coating can significantly enhance modal attenuations over a broader frequency range compared to that for a single-layer coated structure. For a cylinder with radius a=2λ, the attenuation constants for the dominant modes are shown to increase by 20 dB per a by adding a lossless padding layer to a lossy magnetic coating. Application of this result in radar cross-section (RCS) reduction is discussed View full abstract»

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  • Pulse dispersion distortion in open and shielded microstrips using the spectral-domain method

    Publication Year: 1988 , Page(s): 1223 - 1226
    Cited by:  Papers (18)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The spectral-domain method is used to compute the effective dielectric constant [εr/eff(f)] of open and shielded microstrip lines to analyze the dispersion distortion of short electrical pulses. Precise expressions for the longitudinal and transverse current distributions allow a high level of accuracy for εr/eff(f). It is determined that computation time can be minimized for the open microstrip calculations by using the shielded microstrip formulation provided large dimensions for the conducting walls are assumed View full abstract»

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  • A coplanar probe to microstrip transition

    Publication Year: 1988 , Page(s): 1219 - 1223
    Cited by:  Papers (25)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    A transition between a coplanar probe and a microstrip transmission line is reported. The transition is significant in that it does not require substrate via holes. A set of microstrip impedance standards was developed for the purpose of de-embedding the transition. The latter is suitable for measuring the S parameters of a number of low-cost monolithic microwave integrated circuits with coplanar probes View full abstract»

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  • Via hole studies on a monolithic 2-20 GHz distributed amplifier

    Publication Year: 1988 , Page(s): 1191 - 1195
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (616 KB)  

    The effect of source inductance on the performance of a distributed amplifier is investigated. A simple theoretical analysis shows that optimum performance is obtained with as low a source inductance as possible (as would be intuitively expected), and that the flattest gain and minimum gate line attenuation occur with the inductance common to the whole amplifier rather than parceled out to each FET individually, as would occur for a MIC distributed amplifier. A novel through-the-wafer via hole process has been developed for a low-inductance contact on monolithic circuits. A 2-20 GHz variable-gate-width monolithic distributed amplifier fabricated with this via-hole grounding technique has demonstrated a 2-dB gain improvement as well as a flatter gain profile compared to that without via grounding. Evidence is presented that indicates that MMIC (monolithic microwave integrated circuit) designs may not be as ideal as expected with regard to being typified by the common inductance case View full abstract»

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  • Modeling of MODFETs

    Publication Year: 1988 , Page(s): 1124 - 1140
    Cited by:  Papers (4)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1668 KB)  

    Accurate modeling of MODFETs and of certain novel structures recently proposed requires that a number of physical phenomena occurring in these devices be considered. Among these, some electron dynamic properties of the two-dimensional gas, the influence of deep levels of the doped AlGaAs layers, and the influence of the source parasitic access impedance are reviewed. The presently available models can roughly be sorted into three classes: the particle or Monte Carlo models, the two-dimensional solving methods of semiconductor equations, and the simpler one-dimensional or analytical models. After a brief review of the physical bases on which the models rely, their main capabilities and ranges of applicability are discussed. Some conclusions are drawn as to the effort which must be developed in the near future to improve MODFET modeling. It is recommended that simulations of devices such as SISFETs, multichannel structures, and pseudomorphic AlGaAs/InGaAs transistors be undertaken View full abstract»

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  • Microwave detection using the resonant tunneling diode

    Publication Year: 1988 , Page(s): 1145 - 1150
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (524 KB)  

    An experimental and theoretical study in the use of a resonant tunneling diode (RTD) as a microwave detector, based on its small-signal equivalent circuit model, is presented. It is shown that the rectified current from the diode can be accurately predicted and that the diode can be operated as a reactive microwave detector which absorbs no microwave power. For this detection mode, a matching network which maximizes the applied AC voltage can be used View full abstract»

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  • Design procedure for inhomogeneous coupled line sections

    Publication Year: 1988 , Page(s): 1186 - 1190
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    Design formulas are presented, along with a procedure for the design of inhomogeneous coupled line sections as an approximation to a series open-circuited stub for application in the realization of microwave pseudo-high-pass filters. The accuracy of the design equations is evaluated through the design and test of a seventh-order filter and it is found that the formulation predicts the performance of the section well beyond the quarter-wave frequency View full abstract»

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  • The rigorous analysis of cascaded step discontinuities in microstrip

    Publication Year: 1988 , Page(s): 1177 - 1185
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB)  

    A rigorous analysis of boxed microstrip single-step discontinuities and cascades of strongly coupled discontinuities is presented. Use is made of a variational formulation involving the expansion of the transverse E field at the step in terms of suitable basis functions. Strongly coupled steps are analyzed using the concept of localized and accessible modes and making use of a network model. The method is applied to a five-section low-pass filter View full abstract»

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  • A new method for determining the FET small-signal equivalent circuit

    Publication Year: 1988 , Page(s): 1151 - 1159
    Cited by:  Papers (545)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (796 KB)  

    A method to determine the small-signal equivalent circuit of FETs is proposed. This method consists of a direct determination of both the extrinsic and intrinsic small-signal parameters in a low-frequency band. This method is fast and accurate, and the determined equivalent circuit fits the S-parameters well up to 26.5 GHz 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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