IEEE Transactions on Microwave Theory and Techniques

An exact analytical expression for the Maxwell capacitance matrix of a multilayer, multistrip planar or cylindrical line is derived by solving the dual series equation system of the problem by means of a Volterra boundary-value problem. The solution is expressed in terms of some infinite matrices with very good convergence properties. Numerical examples show that the method yields accurate results... View full abstract»

We have demonstrated very good performance, high yield Ka-band multifunctional MMIC results using our recently developed 0.25-μm gate length pseudomorphic HEMT (PHEMT) manufacturing technology. Four types of MMIC transceiver components-low noise amplifiers, power amplifiers, mixers, and voltage controlled oscillators-were processed on the same PHEMT wafer, and all were fabricated using a common... View full abstract»

The single-sideband phase noise of varactor tunable GaAs MESFET oscillators is investigated. Two oscillator circuits with different microstrip resonator circuits were designed and fabricated. Using a resonator consisting of coupled microstrip lines instead of a single microstrip line, which is a planar monolithically integrable structure, phase noise is reduced significantly because the quality fa... View full abstract»

In order to reduce computer memory and computational time required by three dimensional Finite-Difference Time-Domain (FDTD) microwave passive component analysis, two strategies are developed in this paper. First, the recently reported dispersive boundary condition (DEC) is modified thereby enabling the absorbing boundary to be located near to the main field area; second, an exact source plane fie... View full abstract»

The port reflection coefficient method (PRCM) is proposed for the treatment of multi-port microwave network systems. The theory is meaningful because in combination with other available numerical techniques, it can provide several possible ways for simplifying and solving complicated multiport problems. The PRCM also suggests an approach for the measurement of scattering parameters, since it requi... View full abstract»

Two state-of-the-art monolithic GaAs PIN diode switches have been designed, fabricated and tested. These single-pole double-throw (SPDT) switches exhibit insertion losses of 1.15±0.15 dB over a 2-18 GHz band, which is an unprecedented performance in loss and flatness for monolithic wideband switches incorporating on-chip bias networks. Isolation and return loss are greater than 43 dB and 12... View full abstract»

The nonreciprocal characteristics of the planar transmission lines with the layered structures, including magnetized ferrite, are analyzed based on the versatile hybrid-mode formulation that is applicable to various types of shielded and open structures. An accurate and efficient numerical procedure presents the frequency-dependent nonreciprocal values of the phase constants, characteristic impeda... View full abstract»

A Design-Oriented FET model in conjunction with an appropriate design procedure for distributed amplifiers is presented. The advantage of including the effects caused by FET parasitics in a newly defined simple unilateral FET circuit to be utilized in the conventional distributed amplifier design procedure allows an accurate prediction of the low-frequency gain and the 3-dB cutoff frequency. The s... View full abstract»

An efficient technique for the analysis of a general class of microstrip structures with a substrate and a superstrate is investigated in this paper using newly-derived closed-form spatial domain Green's functions employed in conjunction with the Method of Moments (MoM). The computed current distributions on the microstrip structure are used to determine the scattering parameters of microstrip dis... View full abstract»

A solution to the nonlinear problem of drying of a sheet material is presented, which combines basic thermodynamic properties with the field equations. Some results are given in a numerical simulation View full abstract»

The finite-difference time-domain (FDTD) method is extended to include magnetized ferrites. The treatment of the ferrite material is based on the equation of motion of the magnetization vector. Magnetic losses are also included in the equation of motion by means of Gilbert's approximation of the phenomenological Landau-Lifschitz damping term. The discretization scheme is based on central finite-di... View full abstract»

A new type of groove guide, circular groove guide, has been designed for use as a low losses, high power handling, low dispersion and single mode transmission medium in the short millimetric and submillimetric waves ranges. The characteristic equations of TE modes and TM modes have been developed and the propagation characteristics of the fundamental mode have been discussed. Experimental measurem... View full abstract»

In this paper a new TLM model is presented for solving two-dimensional electromagnetic field problems. The new model possesses the same dispersion relation as a fourth-order in space and second-order in time central-finite-difference algorithm. The stability criterion of the TLM model (given in terms of permissible values for the admittance of the permittivity stub) is provided. Investigation of t... View full abstract»

A numerical procedure based on the finite-difference method and simultaneous iteration of the power method in conjunction with the Chebyshev acceleration technique is utilized to analyze the metallic waveguides. Due to the efficiency of the present sparse matrix eigenproblem solver, lots of unknowns can be used in the domains of the waveguide cross-sections. Therefore, accurate cutoff wavenumbers ... View full abstract»

The performance of a spatial power-combining array with device failure is investigated. Experimental results show that the array still combines the power in the broadside direction when the DC open-circuit failure occurs. Analysis of measured radiation patterns indicated that the power radiated from the patch antenna attached to the failed device is much smaller than the power radiated from other ... View full abstract»

An analytical and numerical investigation is made of electric field enhancement due to scattering of an incident plane wave by a biconical conductor. An application to microwave transmit-receive switches (TR) shows that field enhancement factors of the order of 20 to 40 are to be expected in the region close to the keep-alive contacts. An analysis of the microwave absorption by a small plasma sphe... View full abstract»

The quasi-TEM analysis of systems of lossless coupled transmission lines in an inhomogeneous medium is reviewed. Starting from the generalized telegrapher's equations, the characteristic impedance of the normal modes is defined and computed according to the three usual definitions for the single-line case: power-current, power-voltage and voltage-current. Unlike the quasi-TEM single-line case, it ... View full abstract»

In this paper, the dispersion characteristics of a TLM mesh formed by interconnected symmetrical condensed nodes with stubs are calculated using two different formulations. The dispersion relation derived is an implicit function of the wave number, frequency, dielectric permittivity, and magnetic permeability. Group and phase velocities are obtained for the three fundamental directions and differe... View full abstract»

A source-type integral equation method is presented to determine the propagation constants, the radiation losses, and the electromagnetic field distributions of the discrete (“guided”) modes in circularly curved, integrated optical channel waveguides embedded in a homogeneous background. The method can be extended to the case of a multilayered background, e.g. a ridge waveguide. The so... View full abstract»

We describe how coplanar microwave resonators fabricated from patterned thin films of YBa2Cu3O7(-δ) (YBCO) can he used to measure the ab-plane microwave surface impedance Zs=Rs+jXs of the films, in particular the absolute value and temperature dependence of the magnetic penetration depth λ. The current distribution of t... View full abstract»

A general method is formulated for the analysis of signal lines of finite thickness in the presence of a periodically perforated ground plane. Utilizing the dyadic Green's functions, a set of electric and magnetic field integral equations (EFIE, MFIE) is established, which are then transformed into the spectral domain by the Fourier transform. Galerkin's method is used to solve the combined integr... View full abstract»

The increasing use of Heterojunction Bipolar Transistors (HBT's) in microwave analog circuits requires a valid description of these devices by means of an equivalent circuit including noise sources in an extended bias and frequency range. This paper describes a technique to extract the elements of the equivalent circuit from simultaneous noise and S-parameter measurements. Additionally, the conven... View full abstract»

A field matching analysis of a coaxial-to-waveguide adaptor incorporating a disc-ended probe and a tuning post is presented. In this analysis, the tuning post is considered as a short-circuited second probe. A computer algorithm for calculating the input impedance of this structure is developed. This algorithm is used to investigate and improve the operation of a commercially available coaxial-to-... View full abstract»

This paper describes a practical realization of a mixer that achieves low intermodulation distortion by using the channel resistance of a GaAs MESFET to provide mixing and achieves even-order spurious response rejection through the use of a doubly balanced structure. Very good results were achieved in terms of second- and third-harmonic levels of -67 and -45 dBC, respectively, at +10 dBm input lev... View full abstract»

In this paper, an efficient finite element method formulation (FEM) is applied to rotationally symmetric coaxial waveguides, in which the dependence of the dominant TEM mode on the radius of the cylindrical coordinate system is explicitly taken into account in the basis functions. In this way, a physically appropriate approximation of the unknown field distribution is achieved. After scaling, the ... View full abstract»