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Microwave Theory and Techniques, IEEE Transactions on

Issue 11 • Date Nov. 1981

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Displaying Results 1 - 24 of 24
  • [Front cover - Nov. 1981]

    Page(s): f1 - f2
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    Freely Available from IEEE
  • Patent abstracts

    Page(s): 1244 - 1247
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    These patent abstracts of recently issued patents of interest to microwave engineers are intended to provide the minimum information necessary for readers to detennine if they are interested in examining the patent in more detail. Complete copies of patents are available for a small fee by writing: U.S. Patent and Trademark Office, Box 9, Washington, DC, USA. View full abstract»

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  • Announcing A Second Special Issue On Guided Wave Technology To Be Published In The IEEE Journal Of Quantum Electronics And In The IEEE Transactions On Microwave Theory Techniques

    Page(s): 1248
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    Freely Available from IEEE
  • [Back Cover - Nov. 1981]

    Page(s): b1
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    Freely Available from IEEE
  • 94-GHz Beam-Lead Balanced Mixer

    Page(s): 1150 - 1157
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    Using a newly developed GaAs beam-lead diode, we have developed and evaluated a balanced mixer at 94 GHz. The various components of the mixer were separately optimized using carefully designed low-frequency model studies as our primary design aid. These studies included the determination of guide impedance and guide wavelength for suspended stripline, and optimization of a waveguide to suspended stripline transition, low-pass filters, and diode location. This 94-GHz mixer exhibits an average single sideband (SSB) conversion loss of 6.2 dB over a 6-GHz RF bandwidth. Together with a bipolar IF amplifier, the system exhibits a 4.5-5.1-dB double sideband (DSB) noise figure over a 50-700-MHz IF bandpass. LO-to-RF isolation was greater that 27 dB over this range of operating frequencies. Finally, severe environmental test were successfully performed on the mixer between sucessive electrical characterization. View full abstract»

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  • Investigations of Broad-Band, Linear Phase Shifters Using Optimum Varactor Diode Doping Profiles

    Page(s): 1158 - 1164
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    The problem of obtaining linear phase shift of microwave signals over a broad frequency range and its dependence on varactor properties is addressed. An important application of the linear phase shifter, the microwave frequency translator, is investigated in detail and various circuit configurations and varactor doping profiles are examined relative to their performance including suppression of undesired frequency components and bandwidth. Hyperabrupt or Read-type varactor diodes are found to be very useful in this application View full abstract»

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  • An Empirical Relationship for Electromagnetic Energy Absorption in Man for Near-Field Exposure Conditions

    Page(s): 1235 - 1238
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    An empircal relationship is presented for the whole-body-average electromagnetic energy absorption in a 180-cell block model of man for near-field exposure conditions. Consideration is restricted to near fields with P polarization (no component of E directed arm-to-arm) in which the magnitude of the incident electric field is maximum immediately in front of the abdominal region. A highlight of this work is the considerably reduced whole-body average energy absorption for near-field partial-body exposures as compared to that obtained under plane-wave irradiation conditions. View full abstract»

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  • Dielectric Loss in Biogenic Steroids at Microwave Frequencies

    Page(s): 1209 - 1213
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    Dielectric loss in steroids has been measured in solid format 9.4 GHz and in nonaqueous solutions at 3.3 and 9.4 GHz. The method for solutions consists of measurement on standing-wave pattern in front of a column of liquid of varying length and concentration, contained in a short-circuited dielectric cell. Keeping the concentration within the limits of dilute solutions, dipole moment and relaxation time of Cholesterol, Progesterone, and Testosterone have been evaluated. Mechanisms responsible for dielectric loss and its trend of variation in the three steroids are presented. The solid phase measurements were carried out by cavity perturbation technique on powders and crystal values, for epsilon' and epsilon" were evaluated. The difference in epsilon" values of the three steroids in the two phases is attributed to the difference in the mechanism of microwave absorption. However, identical values of epsilon' are obtained. View full abstract»

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  • A Method for Diminishing Total Transmission Losses in Curved Dielectric Optical Waveguides

    Page(s): 1182 - 1187
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    A practical method for diminishing total transmission losses in curved dielectric optical slab waveguides is proposed. Asymmetric structures are introduced into curved sections. It is found that there exists an optimum asymmetric structure for the curved section which makes the total transmission loss minimum. And it is also found that the characteristics of total transmission loss do not critically depend upon the asymmetry of waveguide structure, so that some displacement from the optimum structure does not increase the loss in an appreciable amount. View full abstract»

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  • Probing Amplitude, Phase, and Polarization of Microwave Field Distributions in Real Time

    Page(s): 1225 - 1231
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    A coherent (homodyne) detection system is used to map field distributions in real time. A key feature is the use of an electrically modulated (10-kHz) dipole scatterer which is also mechanically spun (150 Hz) to create an amplitude- and phase-modulated backscattered field. The system is monostatic. The backscattered field is coherently detected by mixing with the CW reference. A phase-insensitive detector is used, comprised of two balanced mixers which are fed in quadrature phase by one of the RF inputs followed by a phase quadrature combiner. The resulting amplitude and phase of the 10-kHz output are proportional to the square of the RF field component along the instantaneous axis of the spinning dipole. Both are measured simultaneously and independently in real time. From these, the polarization properties can also be found, so the field is uniquely described. The system's application to scanning the E-field transmitted through Iossy, nonhomogeneous and anisotropic media (e.g., wood) is demonstrated. Other applications besides nondestructive testing are microwave vector holography, nearfield antenna measurements, and inverse scattering. View full abstract»

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  • An Easy Tunable Stepped Coupled Lines Filter

    Page(s): 1238 - 1240
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    A stripline bandpass filter setup consisting of two stepped coupled lines is presented, with special emphasis being given to practical realization. The theoretical design of the filter is based on the known synthesis of directional couplers and is outlined briefly. Practical setup of the filter, together with a simple tuning mechanism, is described in detail. Measurements performed show good agreement with theoretical results. View full abstract»

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  • Spurious Resonances in Asymmetrical Fin-Line Junctions

    Page(s): 1193 - 1195
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    Spurious resonances which occur in asymmetrical fin-line junctions are investigated. The field distribution and the resonant frequency are computed using a field matching technique. Looking at the field distribution, methods for resonance suppression are discussed. View full abstract»

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  • Planar Broad-Band 180° Hybrid Power Divider/Combiner Circuit

    Page(s): 1233 - 1235
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    A planar broad-band 180° hybrid is presented. The hybrid is realized using a 3-dB 90° hybrid and a 0-dB 90° tandem hybrid. An interdigitated version of the hybrid fabricated on alumina substrate performed well over the 4-8-GHz band. The hybrid has an insertion loss of 0.5 dB, phase imbalance of +-7°, and an isolation of better than 18 dB over the band. View full abstract»

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  • Nonradiative Dielectric Waveguide for Millimeter-Wave Integrated Circuits

    Page(s): 1188 - 1192
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    A nonradiative dielectric waveguide is proposed in which dielectic strips are sandwiched between two parallel metal plates separated by a distance smaller than half a wavelength. Though the structure is substantially the same as that of the H-guide, it is based on a quite different principle of operation. This dielectric guide is particularly applicable in millimeter-wave integrated circuits, since it is not only small in size, but also allows bends and junctions to be incorporated into the circuits with very little radiation and interference. A design diagram is given. Losses and coupling coefficients of the strips are calculated, as well. Some basic circuit components, such as 90° and 180° bends and T-junctions, made of polystyrene strips, are measured to confirm their usefulness in millimeter-wave integrated circuits. View full abstract»

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  • Stability Analysis of Injection-Locked Oscillators in Their Fundamental Mode of Operation

    Page(s): 1137 - 1144
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    Phase-lock stability of fundamental-wave injection-synchronized oscillators is investigated on the basis of a new time-domain approach. Starting from a quite general oscillator modeling and assuming single-frequency quasi-static operation, both exact and first-order approximate stability criteria are derived in a fully analytical form suitable for computer implementation. The examples worked out demonstrate good agreement of this theory with experimental observations available in the literature on multiple-tuned oscillators, whose behavior under large-signal injection was so far predictable only through graphical methods. View full abstract»

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  • The Thermal Dielectric Quotient for Characterizing Dielectric Heat Conductors

    Page(s): 1231 - 1233
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    If a piece of dielectric is mounted between two conductors, the resulting thermal conductance and electrical capacitance are related by their quotient which is a property of the material, independent of the size and shape. This quotient is expressed in watts per (picofarad X kelvin). It is helpful in the selection of a material for conducting heat while adding least capacitance. For example, a beryllia ceramic block of 1 pF can conduct about 4 W/K. The highest is a diamond of unusual perfection, about 40 W/K. A table and a nomogram give these properties for a variety of materials. View full abstract»

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  • A Laser-Induced Traveling-Wave Device for Generating Millimeter Waves

    Page(s): 1174 - 1182
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    We have investigated a novel device concept for generating CW millimeter waves with output power in the multiwatt range. The concept involves the utilization of modulated laser radiation to induce in a distributed Schottky-diode structure a traveling-wave current which, in turn, synchronously excites the dominant mode of a waveguide structure to generate millimeter power. The induced traveling-wave current is directly proportional to the laser modulation generated by the interference of two overlapping laser beams of millimeter beat frequency. Detailed analysis indicates that the device has both high-output and frequency-tunable characteristics. View full abstract»

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  • Analysis of Miniature Electric Field Probes with Resistive Transmission Lines

    Page(s): 1213 - 1224
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    The miniature dipole probe is a useful tool for measuring the electric field at high radio and microwave frequencies. A common design for the probe consists of an electrically short dipole antenna with a diode across its terminals; a resistive, parallel-wire transmission line transmits the detected signal from the diode to the monitoring instrumentation. The high resistance per unit length of the transmission line reduces the direct reception of the incident field by the line and also reduces the scattering of the incident field by the line. In addition, the resistive transmission line serves as a low-pass filter in the detection process. In this paper, the effect of the resistive transmission line on the operation of the miniature field probe is analyzed. Specifically, the reception of the incident signal by the transmission line is compared with that of the dipole. The scattering of the incident signal by the transmission line is studied by means of the scattering cross section, and the limitation imposed on the measurement of amplitude-modulated signals by the low-pass filtering by the resistive line is examined. The results of the theoretical analyses are presented as simple formulas which are useful in the design and optimization of the probe. The theoretical results are shown to be in good agreement with measurements. View full abstract»

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  • Corrections to "Design of Cylindrical Dielectric Resonators in Inhomogeneous Media"

    Page(s): 1243
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    In the above-referenced paper, the following corrections should be made. View full abstract»

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  • Energy Absorption from Small Radiating Coaxial Probes in Lossy Media

    Page(s): 1202 - 1209
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    This paper describes the calculation of energy deposition around small open-ended coaxial antenna probes in lossy media. Two theoretical methods, a small monopole approximation (I) and an equivalent magnetic current source (II), are evaluated and compared. Method I is shown to be inappropriate for determining near field energy deposition. Power contour plots determined by method II in the vicinity of the open-ended coaxial antenna are presented as well as calculations of total power absorbed as a function of distance from the antenna center for various antenna dimensions and media dielectric properties. Our calculations of absorbed power distributions near the antenna are consistent with the limited experimental data which is available for comparison. A frequency of 2.45 GHz was selected for these calculations so that the results will be of value to workers interested in the application of own-ended coaxial antennas for invasive treatment of cancer by microwave hyperthermia. View full abstract»

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  • Synthesis of Transformer Coupled Multiple Frequency Circulators with Chebyshev Characteristics

    Page(s): 1165 - 1173
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    This paper presents a theory for broad-band matching of stripline junction circulators for operation in two or more frequency bands. In this theory it is assumed that the matching network is composed of cascaded transmission line transformers each of which is an odd multiple of a quarter-wavelength at the center frequencies. The conditions for simultaneous Chebyshev response in multiple frequency bands are determined, and it is investigated to what extent these conditions can be satisfied by stripline circulator junctions. Thus by using a first-order theory, it is shown that if a circulator junction, adjusted for double frequency operation, is matched for Chebyshev response by a transformer of proper length around one of the circulation frequencies then it is also matched for Chebyshev response around the other circulation frequency, provided that the same operation mode is used above and below material resonance. A routine for broad-band multiple frequency matching is proposed for junctions where Chebyshev response is not obtainable. Finally the properties of some externally matched circulators designed according to the theories are shown. View full abstract»

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  • Boundary Integral Equation Analysis of Transmission-Line Singularities

    Page(s): 1240 - 1243
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    The TEM line analysis of microstrips and coaxial lines generally involves boundary singularities which cause slow convergence of solutions computed by standard numencal techniques. In this study, the singularities occurring at the ends of the inner conductor in an unsymmetric closed microstrip containing a dielectric substrate, are treated by a modified boundary integral equation method. This method is shown to be successful in reducing the error due to the presence of the singularities. View full abstract»

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  • Analysis of Schottky-Barrier Millimetric Varactor Doublers

    Page(s): 1145 - 1149
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    An analysis of abrupt-junction millimetric varactor doublers using Schottky diodes is performed and numerically implemented to evaluate conditions of maximum output power. This power level, the efficiency, and the circuit parameters have been derived as a function of the geometrical and physical parameters of the junction. Physical phenomena which allow the application of the model up to the plasma resonance frequency in epilayer are taken into account. Comparison of available experimental data with the theory developed is repotted. View full abstract»

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  • Equivalent Reactance of a Shorting Septum in a Fin-Line: Theory and Experiment

    Page(s): 1196 - 1202
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    This paper presents the results of theoretical and experimental investigations of the equivalent reactance of a shorting septum in a fin-line. Numerical and experimental data showing septum reactance for several different fin-lines are presented and compared. Some design curves are included for millimeter-wave fin-lines with this type of discontinuity 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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