Showing papers in "IEEE Transactions on Microwave Theory and Techniques in 1983"
TL;DR: In this article, the authors summarized different power-combining techniques and their performance, with particular emphasis on millimeter-wave developments, and discussed the tradeoffs of these techniques and future trends predicted.
Abstract: This paper summarizes different power-combining techniques and their performance, with particular emphasis on millimeter-wave developments. The tradeoffs of these techniques are discussed and future trends predicted.
399 citations
TL;DR: In this paper, the distribution of current in and the admittance of a center-driven dipole embedded in a general medium are reviewed, and the electric field generated by the currents in the dipole is derived for all points outside the antenna.
Abstract: Insulated antennas are useful for localized heating as in the hyperthermia treatment of tumors and the extraction of shale oil. The distribution of current in and the admittance of a center-driven dipole embedded in a general medium are reviewed. Formulas for the electric field generated by the currents in the dipole are derived for all points outside the antenna. Near the antenna, the field is elliptically polarized. Formulas for the polarization ellipses are derived and evaluated for antennas with electrical half-lengths Beta/sub L/h = pi/4, pi/2, pi, and 3pi/2, where k/sub L/ =beta/sub L/ + i alpha/sub L/ is the wavenumber of the current, and this is different from the wavenumber of the ambient medium.
214 citations
TL;DR: In this article, the effect of surface waves on dipole and slot elements on substrates was considered and the radiation and bandwidth of microstrip dipoles were optimized in terms of substrate thickness and permittivity.
Abstract: The reciprocity theorem and integral equation techniques are employed to determine the properties of integrated-circuit antennas. The effect of surface waves is considered for dipole and slot elements on substrates. The radiation and bandwidth of microstrip dipoles are optimized in terms of substrate thickness and permittivity.
210 citations
TL;DR: In this article, a computer-aided design is described that makes it possible to reduce the internal impedance levels of branch line couplers so that they may be physically constructed by microstrip lines, where the Fletcher-Powell search method has been used to optimize the design.
Abstract: A computer-aided design is described that makes it possible to reduce the internal impedance levels of branch-line couplers so that they may be physically constructed by microstrip lines, where the Fletcher-Powell search method has been used to optimize the design. Because microstrip lines are severely restricted in their usable impedance range, the 3-dB couplers presented here should be useful for numerous balanced-type components such as balanced mixers. The validity of the design has been experimentally verified in the microwave and millimeter-wave region.
202 citations
TL;DR: In this article, a simple model to estimate the effects of light on the dc and RF properties of MESFET'S is presented, where photoconductive and photovoltaic effects in the active channel and substrate are considered to predict the change in the dc equivalent circuit parameters of the FET.
Abstract: Theoretical and experimental work for the performance of GaAs MESFET's under illumination from light of photon energy greater than the bandgap of the semiconductor is described. A simple model to estimate the effects of light on the dc and RF properties of MESFET'S is presented. Photoconductive and photovoltaic effects in the active channel and substrate are considered to predict the change in the dc equivalent circuit parameters of the FET, and from these the new Y- and S-parameters under illumination are calculated. Comparisons with the measured S-parameter's without and under illumination show very close agreement. Optical techniques can he used to control the gain of an FET amplifier and the frequency of an FET oscillator. Experimental results are presented showing that the gain of amplifiers can be varied up to around 20 dB and that the frequency of oscillators can be varied (tuning) around 10 percent when the optical absorbed power in the active region of the FET is varied by a few microwatts. When the laser beam is amplitude-modulated to a frequency close to the free-running FET oscillation frequency, optical injection locking can occur. An analytical expression to estimate the locking range is presented. This shows a fair agreement with the experiments. Some suggestions to improve the optical locking range are presented.
201 citations
TL;DR: In this paper, a moment method solution procedure for rotationally symmetric dielectric bodies has been applied to isolated cylindrical D resonators, and the frequencies, as well as Q factors due to radiation, have been determined for several of the lowest modes, including those of hybrid type.
Abstract: A moment method solution procedure for rotationally symmetric dielectric bodies has been applied to isolated cylindrical dielectric resonators, and the frequencies, as well as Q factors due to radiation, have been determined for several of the lowest modes, including those of hybrid type.
168 citations
TL;DR: In this paper, the phase constant of the leaky modes supported by the antenna structure of finite lateral width is derived from the relatively simple boundary value problem of dielectric grating antennas of infinite width.
Abstract: At theoretical procedure well suited for generating design data on dielectric grating antennas for the millimeter-wave region is presented. The procedure utilizes the effective dielectric constant (EDC) method to determine the phase constant of the leaky modes supported by the antenna structure of finite lateral width. The radiation or leakage constant of these modes is obtained from the relatively simple boundary value problem of dielectric grating antennas of infinite width. For single-beam radiation, the practicably interesting case, the phase and leakage constants completely determine the field distribution in the antenna aperture, from which the directivity gain and radiation pattern are then calculated. The dependence of the antenna characteristics on the dimensions of the radiating structure is presented and discussed for epsilon = 12, the dielectric constant of typical millimeter-wave materials, such as silicon and GaAs.
167 citations
TL;DR: In this paper, the relation for the determination of unloaded, loaded, and external quality factors, in terms of directly measurable reflection or transmission coefficient at the resonant frequency, have been derived and represented on the corresponding vectorial and scalar planes.
Abstract: In the case of a dielectric resonator coupled to a microstrip line, the relations for the determination of unloaded, loaded, and external quality factors, in terms of directly measurable reflection or transmission coefficient at the resonant frequency, have been derived and represented on the corresponding vectorial and scalar planes. Construction of a linear frequency scale and a graphical method to accurately determine the unloaded Q from the loaded Q measurement presented.
162 citations
TL;DR: In this paper, a rapidly converging moment solution for electromagnetic scattering by a single inductive post in a rectangular waveguide is obtained, and the numerical results show good agreement with Marcuvitz's data as far as this data goes.
Abstract: A rapidly converging moment solution for electromagnetic scattering by a single inductive post in a rectangular waveguide is obtained. The numerical results show good agreement with Marcuvitz's data as far as this data goes. Furthermore, Marcuvitz's curves are extended to cover data for large posts. This new data should aflow one to design a simply constructed new type of narrow bandpass filter, namely, a filter consisting of large single posts. The successful use of this straightforward moment solution in solving the single-post problem suggests that this technique should prove useful in solving a variety of microwave discontinuities such as those involving thin or thick irises and posts of arbitrary shape.
159 citations
TL;DR: In this paper, the admittance inverter parameters of the coupling gaps between resonant sections are deduced from experiment, and bandpass filter design rules are developed, which allows easy filter synthesis from "prototype" low-pass designs.
Abstract: End-coupled resonator bandpass filters built in coplanar waveguide are investigated. The admittance inverter parameters of the coupling gaps between resonant sections are deduced from experiment, and bandpass filter design rules are developed. This allows easy filter synthesis from "prototype" low-pass designs. Measurements of single section resonator quality factors are used to predict filter insertion losses. Several examples of filters realized in coplanar waveguide are presented. Odd-mode coplanar waveguide filter elements that shortcircuit the even coplanar waveguide mode are investigated. Filter tuning, accomplished by adjusting the height of conducting planes above the resonant filter sections, is demonstrated.
156 citations
TL;DR: In this paper, a technique for improving the power-added efficiency of linear, class-A FET power amplifiers operating with varying-envelope signafs is proposed.
Abstract: A technique is proposed for improving the power-added efficiency of linear, class-A FET power amplifiers operating with varying-envelope signafs. It involves dynamically controlling the gate "dc" bias voltage with the envelope of the input RF signal. It is shown theoretically that this technique, which is referred to as "class A," results in a significant improvement in the power-added efficiency over standard class A, independently of the FET power gain. The efficiency is also better than that of standard class B if the FET gain is less than about 10 dB, which is the case normally encountered at higher microwave frequencies. The practical implementation of class /sup /spl equiv//A requires FET's with essentially linear drain-current-versus-gate-voltage transfer characteristics.
TL;DR: In this paper, the slow-wave characteristics of an MLS coplanar waveguide were analyzed using two different full-wave methods mode-matching and spectral-domain technique, and the theoretical results obtained with them and the experimental values were in good agreement.
Abstract: The slow-wave characteristics of an MLS coplanar waveguide are analyzed using two different full-wave methods mode-matching and spectral-domain technique. The theoretical results obtained with them and the experimental values are in good agreement. Several important features of the MIS coplanar waveguide are presented along with some design criteria.
TL;DR: In this paper, the performance characteristics of n-link distributed amplifiers employing GaAs MESFET'S are studied and several three-link hybrid amplifiers utilizing the equal line lengths approach have been assembled and test results are reported.
Abstract: The performance characteristics of n-link distributed amplifiers employing GaAs MESFET'S are studied. At first, formulas of tie symmetrical amplifier using lumped circuit elements are developed for the case of an idealized FET model. The theoretical analysis is then extended to distributed line elements and later to an S-parameter derived transistor model. In efforts to optimize amplifier performance, the restriction of circuit symmetry is subsequently removed and the performance characteristics of two concepts, that of equal characteristic impedances and that of equal line lengths, are proposed and compared. Based on this analysis and practical considerations, several three-link hybrid amplifiers utilizing the equal line lengths approach have been assembled and test results are reported. A gain of G = 5.5+-0.6 dB was measured over the bandwidth of 2-20 GHz. Across this frequency band a maximum VSWR of 2.2:1 for the input and 2.5:1 for the output terminaf have been reafized, while a minimum output power at the l-dB compression points of 19.3 dBm was achieved from 2-18 GHz. Agreement between measured and computed small-signal gain as well as reverse isolation is excellent.
TL;DR: In this paper, a design theory for rectangular waveguide metal insert filters that includes both higher order mode interaction and finite thickness of the inserts is described, and optimized design data for three-to five-resonator type filters with severaf insert thicknesses suitable for metal stamping and etching techniques are given for midband frequencies of about 15, 33, 63, and 75 GHz.
Abstract: A design theory is described for rectangular waveguide metal insert filters that includes both higher order mode interaction and finite thickness of the inserts. Optimized design data for three- to five-resonator type filters with severaf insert thicknesses suitable for metal stamping and etching techniques are given for midband frequencies of about 15, 33, 63, and 75 GHz. Measured passband insertion losses of prototypes for mid-band frequencies of 15, 33, and 76 GHz are 0.2, 0.6, and 0.7 dB, respectively.
TL;DR: In this paper, small-signal two-port circuit models of packaged broad-stripe and buried-heterojunction AlGaAs laser diodes are presented based on the single-mode rate equations, and include the heterojunction I-V and space-charge characteristics.
Abstract: Small-signal two-port circuit models of packaged commerical broad-stripe and buried-heterojunction AlGaAs laser diodes are presented. The models are based on the single-mode rate equations, and include the heterojunction I-V and space-charge characteristics. Also included are package and substrate parasitic. The models agree well with measured reflection coefficient and modulation frequency response data, and can be incorporated in standard microwave circuit analysis programs.
TL;DR: In this article, a method for the accurate determination of resonant frequencies of any mode excited in dielectrically loaded wavegnide cavities is described, which is used to construct mode charts for dielectric resonators.
Abstract: Analysis of nonaxially symmetric modes in circular wave-guides partially filled with high-dielectric constant material is presented. A method for the accurate determination of resonant frequencies of any mode excited in dielectrically loaded wavegnide cavities is described. The method is used to construct mode charts for dielectric resonators. Comparison of the resonant frequency calculations for several cases agrees closely with measurements.
TL;DR: In this paper, a fast analytical method is given for determining perrnittivity characteristics at microwave frequencies using a single moded cylindrical waveguide filled with dielectric and followed by a load or by a moving short.
Abstract: A fast analytical method is given for determining perrnittivity characteristics at microwave frequencies. The experimental setup uses a single-moded cylindrical waveguide filled with dielectric and followed by a load or by a moving short. In this way, transmission-reflection and short-circuited line methods are compared. by including the uncertainties in length and in the reflection and transmission parameters, the permittivity uncertainty region is determined. It is shown that for optimum accuracy of the permittivity, specific lengths in combination with a moving short are needed.
TL;DR: In this article, the Finite Element Method (FEM) and the Method of Moments (MOM) were applied to a pair of coupled integral equations to solve the static conductor-dielectric problems.
Abstract: Numercal methods are applied in the analysis of coaxial structures used as sensors for in vivo permittivity studies of biological substances. The methods used for the solution of the resulting static conductor-dielectric problems are the Finite Element Method (FEM) and the Method of Moments (MOM) applied to a pair of coupled integral equations. A linear model which relates the sample permittivity to the fringing field capacitance of the sensor is discussed and values of the model parameters are calculated for different types of sensors.
TL;DR: Complex permittivities are estimated for a 36-cell model which represents the chest portion of the block model of man by using moment-method formulation of the electric field integral equation as discussed by the authors.
Abstract: Complex permittivities are estimated for a 36-cell model which represents the chest portion of the block model of man by using moment-method formulation of the electric field integral equation The errors in the calculated complex permittivities are lower with saline/water the surrounding medium, as compared to air, presumably on account of better matching of energy to the biological body It has been shown that the rest of the human body has little effect on the estimation of complex permittivities because of the near-field natore of the illuminating sonrces small number of buried cells can be handled for solving the inverse problem, but the problem becomes ill-posed and unsolvable for a larger number of buried cells
TL;DR: In this article, a comprehensive study of single-gate GaAs FET frequency doublers is presented, with special emphasis on exploring high-frequency limitations, while yielding explanations for previously observed lower frequency phenomena as well.
Abstract: A comprehensive study of single-gate GaAs FET frequency doublers is presented. Special emphasis is placed on exploring high-frequency limitations, while yielding explanations for previously observed lower frequency phenomena as well. Extensive Iarge-signal simulations demonstrate the underlying relationships between circuit performance characteristics and principal design parameter. Verifying experiments include straight frequency doubler and a self-oscillating doubler, both with output signal frequencies in Ku-band. The self-oscillating doubler appears especially attractive, yielding an overall dc-to-RF efficiency of 10 percent. The type of transistor employed in the numerical and experimental examples possesses a gate length of 0.5 µm and a gate width of 250 µm.
TL;DR: In this paper, a continuous spectra of the complex refractive index and complex dielectric permittivity were given in the millimeter range for a variety of potentially useful materials.
Abstract: Highly accurate continuous spectra of the complex refractive index and complex dielectric permittivity are given in the millimeter range for a variety of potentially useful materials. The absorption coefficient is found to increase monotonically with increasing frequencies. Small amounts of glassy inclusions or water were found to increase losses at all frequencies, but impurities and radiation damage (except in semiconductors) have not yet proved to be detrimental to performance. Materials have been found for which the millimeter-wave losses can be tolerated when used as dielectric waveguide, high-power windows, and other applications. Nominal consideration must be given, however, to the conditions of preparation and the nature of contaminants, The measurements were made in a modular, polarizing, dispersive Fourier-transform spectrometer.
TL;DR: Theoretical expressions for the interelectrode capacitance and conductor losses for an array of microstrip transmission lines are presented in this article, where the effect of finite conductor thickness is included in the analysis by introducing equations for the effective width of the transmission lines.
Abstract: Theoretical expressions for the interelectrode capacitance and conductor losses for an array of microstrip transmission lines are presented. The effect of finite conductor thickness is included in the analysis by introducing equations for the effective width of the transmission lines. Good agreement between theory and experiment is observed up to 18 GHz. Experimental results obtained from a lumped-element GaAs monolithic bandpass filter are in excellent agreement with theory. The filter has 1.5-dB insertion loss at 11.95 GHz and greater than 22-dB loss in the stopband. The filter measures 0.58x 1.3x0.203 mm.
TL;DR: In this article, a basic experiment conducted in water at 3 GHz yielded information on spatial resolution and temperature sensitivity, and the potential capabilities and limitations of this remote-sensing approach in more complicated situations.
Abstract: Recent results have demonstrated the feasibility of quasi-real-time, active as well as harmless microwave imaging for biomedical purposes. Such a process allows tomographic reconstructions based on differences in the complex permittivity of tissues, the temperature dependence of which can be used for remote thermal sensing. A basic experiment conducted in water at 3-GHz yielded information on spatial resolution and temperature sensitivity. Discussion is devoted to potential capabilities and limitations of this remote-sensing approach in more complicated situations.
TL;DR: In this article, a computer-aided design (CAD) algorithm has been developed for a class of E-plane bandpass filters, based on the residue-calculus technique and a generalized scattering parameter method.
Abstract: A computer-aided design (CAD) algorithm has been developed for a class of E-plane bandpass filters. The analysis portion of the algorithm is based on the residue-calculus technique and a generalized scattering parameter method. It is mathematically exact and numerically very efficient. Filters designed with this method have been fabricated and tested in Ku-band. Good agreement with design has been obtained.
TL;DR: In this paper, a moment procedure for solving waveguide junction problems is given using the generalized network formulation for aperture problems, applied to a transverse planar junction between two uniform cylindrical waveguides.
Abstract: A moment procedure for solving waveguide junction problems is given using the generalized network formulation for aperture problems. As an illustration, the procedure is applied to a transverse planar junction between two uniform cylindrical waveguides. The generalized admittance network representation of the junction is first obtained. Its scattering matrix representation is then deduced from the former representation. A discussion shows that the conservation of complex power technique, which handles the same class of junctions, is, a specialization of the moment procedure.
TL;DR: In this article, the results of an experimental investigation of microwave characteristics of a GaAs MESFET under optically direct-controlled conditions were presented, and it was found that they can be controlled by varying the incident light intensity in the same manner as when varying the gate bias voltage.
Abstract: This paper presents the results of an experimental investigation of microwave characteristics of a GaAs MESFET under optically direct-controlled conditions. The gain, drain current, and S-parameters were measured under various optical conditions in the frequency region from 3.0 GHz to 8.0 GHz, and it was found that they can be controlled by varying the incident light intensity in the same manner as when varying the gate bias voltage. As applications of this phenomenon, optical/microwave transformers and an optically switched amplifier were investigated.
TL;DR: In this article, a single-stage and two-stage monolithic GaAs traveling-wave power amplifier with over 250mW power output in the 2-20GHz frequency range is described.
Abstract: Power amplification in FET traveling-wave amplifiers is examined, and the mechanisms which limit power capability of the amplifier are identified. Design considerations for power amplification are discussed. A novel single-stage and two-stage monolithic GaAs traveling-wave power amplifier with over 250-mW power output in the 2-20-GHz frequency range is described.
TL;DR: In this article, a matched symmetric stripline five-port with a perfect directional coupler was proposed for six-port measurements. But the coupler is a four-way divider network.
Abstract: A six-port consisting of a matched reciprocal Iossless five-port in series with a perfect directional coupler is shown to have ideal six-port properties according to the theory developed by Engen. The q points are separated by 120° on a common circle. The matched five-port itself is shown to function as a four-way divider network and bears an interesting analogy with a matched nonreciprocal Iossless three-port (circulator). This analogy is used to design several styles of matched symmetrical stripline five-ports for use in making six-port measurements.
TL;DR: In this article, an integrated planar antenna-mixer structure for use at millimeterwave frequencies is described, and a simple but accurate theory of the slot-ring antenna is applied to several experimental devices.
Abstract: An integrated planar antenna-mixer structure for use at millimeterwave frequencies is described. A simple but accurate theory of the slot-ring antenna is applied to several experimental devices. Mixer conversion loss of about 6.5 dB was obtained from an X-band model. Measured radiation patterns of structures designed for 65 GHz agree reasonably well with theory.
TL;DR: The basic philosophy and the general structure of a user-oriented program package capable of designing broad classes of nonlinear microwave subsystems are described and the application to a practical medium-power oscillator shows that the program is numerically efficient and yields well-defined and accurate results.
Abstract: The paper describes the basic philosophy and the general structure of a user-oriented program package capable of designing broad classes of nonlinear microwave subsystems. Some of the peculiar aspects of the nonlinear design problem and the computer solutions adopted are discussed in detail. The application to a practical medium-power oscillator shows that the program is numerically efficient and yields well-defined and accurate results. Furthermore it provides full coverage of several aspects of circuit performance that were previously treated by empirical approaches, such as detailed effects of higher harmonics, active device operating temperatures, and circuit regulations.