Wave Transmission Line Research Articles

Bistable Microwave Oscillator Based on Nonlinear Magnetostatic Wave Transmission Line

A microwave oscillator containing a GaAs amplifier, a magnetostatic spin wave (MSW) signal-to-noise enhancer (SNE) used as a nonlinear transmission line, directional couplers, and a variable attenuator has been designed and investigated. It was shown, that nonlinearity of the SNE and amplifier resulted in a bistability in the system: two different levels of oscillation power correspond to one attenuator setting. The oscillator was switched on under action of external short low power microwave pulses.

Network analyses for transmission characteristics of several kinds of curve-shaped groove waveguides

In this paper, the several kinds of the novel curve-shaped groove guides including the whole elliptic-, whole cosine- and hyperbolic-groove guides as the new millimeter wave transmission lines are presented. The dispersion, cut-off and band characteristics of the dominant mode for the several kinds of the curve-shaped groove guides are analysed by using the equivalent network method with transverse resonance. The obtained results have important values in their theoretical studies and actual applications of the curve-shaped groove waveguides.

Using Mathcad in electromagnetics education

Mathcad is an effective learning tool in electromagnetics courses. Use of Mathcad by students in such courses at the University of Denver incorporate four essential ingredients needed for the successful integration of computer aided learning into a curriculum component: (1) involvement by the student in establishing what is to be analyzed by the computer; (2) a general purpose tool rather than concept-specific software; (3) a user friendly interface; and (4) effective integration of the computational tool(s) into the course. This paper gives examples of the use of Mathcad in the subject areas of electrostatics, plane wave propagation, transmission lines, antennas, and advanced topics.

Modulation of magnetostatic surface wave in garnet film by optical pulses

Microwave power modulation in a magnetostatic surface wave (MSSW) transmission line containing an yttrium-iron-garnet film of thickness 20 μm in the 3–4 GHz frequency band with optical pulses of duration 2 ms and energy of 20 μJ has been investigated. At microwave powers less than 1 mW a slow thermal modulation with magnitude up to 4% and characteristic time of 0.5 ms took place. At power levels 1–100 mW a fast modulation of the transmitted signal with magnitude up to 10% and characteristic time of about 1 μs caused by nonlinear properties of MSSW was observed.

Optical control of microwave signals inmagnetostatic wave transmission lines

The possibility of controlling the parameters of microwave signals by pulsed optical heating of ferrite film in a magnetostatic wave transmission line is demonstrated. Variations of the phase shift by 10π rad, a delay time of 35 ns, and a signal power of 5 dB were obtained for a 5.7 GHz signal at a laser pulse energy of ~30 mJ.

Mathcad

Discusses the use of Mathcad software in an electrical engineering course. It is used to solve problems in electromagnetism such as electrostatics, plane wave propagation, antennas and transmission lines.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The uniqueness and existence of solution of the characteristic problem on the generalized KdV equation

The generalized KdV equationu 1+auua+μua3+eua5=0[1] is a typical integrable equation. It is derived studying the dissemination of magnet sound wave in cold plasma[2], the isolated wave in transmission line[3], and the isolated wave in the boundary surface of the divided layer fluid[4]. For the characteristic problem of the generalized KdV equation, this paper, based on the Riemann function, designs a suitable structure, then changes the characteristic problem to an equivalent integral and differential equation whose corresponding fixed point, the above integral differential equation has a unique regular solution, so the characteristic problem of the generalized KdV equation has a unique solution. The iteration solution derived from the integral differential equation sequence is uniformly convegent in $$\bar \Omega $$ .

Transmission and radiation properties of a surface wave transmission line with a bend

AbstractAs a cause of generation of unwanted electromagnetic radiation, the bend of a surface wave transmission line is investigated. The transmission and radiation characteristics at the bend are studied analytically and experimentally. First, by applying the traveling wave mode method, it is shown that the transmission characteristics of the surface wave transmission line can easily be obtained. The change of the equivalent voltage near the bend is observed.Next, the discontinuity of the traveling wave current is considered as a radiating source and the radiation field from the bend in a surface wave transmission line is derived by means of the principle of pattern multiplication. It is found that there exist an electric field component which strongly radiates into the traveling directions of the current in a bent transmission line and the component which radiates into the intermediate direction. It is found that the power is radiated strongly into the intermediate direction. Further, by experiments which agree well with the theoretical results, the validity of the method is presented.

High-frequency generation by electromagnetic shock wave in transmission line with nonlinear capacitance

Conditions are studied for the effective generation of high-frequency oscillations by an electromagnetic shock wave in a transmission line with space dispersion and nonlinear capacitance with hysteresis —fast saturation with field activation and retention of that state for a long time after field deactivation. A version of such a capacitance with “memory” based on a multilayer heterostructure with an “activation” delay on the order of 10−13 sec is proposed.

Propagation Characteristics and Mode Utilizability of Electromagnetic RF and Optical Surface Waves Travelling between a Pair of Metal Sheets

Several characteristic features of electromagnetic (EM) surface waves propagating between a pair of planar conductors are disclosed analytically along with the other normal EM modes. The solutions are obtained on the basis of electron plasma oscillation in metals. The results are summarized as follows: (I) there exist primarily two independent surface waves (or optical surface waves), even and odd surface modes; (II) the odd surface mode (SWo) becomes a pure transverse electromagnetic (TEM) wave in the limiting case of an infinite value of electron density in metals; and (III) the even surface mode (SWe) will smoothly change to the even TM1e mode at a certain point of the dispersion curve. Utilizability of the lower modes is discussed for very-high-frequency RF and optical wave transmission lines and for long or large-area plasma production between planar electrodes.

High temperature superconducting Josephson transmission lines for pulse and step sharpening

An increasing number of high speed digital and other circuit applications require very narrow impulses or rapid pulse edge transitions. Shock wave transmission lines using series or shunt Josephson junctions are one way to generate these signals. Using two different high temperature superconducting Josephson junction processes (step-edge and electron beam defined nanobridges), such transmission lines have been constructed and tested at 77 K. Shock wave lines with approximately 60 YBaCuO nanobridges, have generated steps with fall times of about 10 ps. With step-edge junctions (with higher figures of merit but lower uniformity), step transition times have been reduced to an estimated 1 ps.

Slow wave transmission line transformers

Development of a periodic structure to coupled slow- and fast-wave transmission lines is described. The slow-wave line is a coaxial line with rectangular corrugations on the outer conductor and with smooth metallic walls for the inner conductor. The fast-wave structure is a coaxial line with smooth inner and outer metallic conductors, or with outer conductors where the corrugation depth approaches zero. The unit cells, or quarter-wave sections, are developed for both binomial and Chebyshev coefficients. The Chebyshev transformer is designed for arbitrary bandwidths from 1.0 to larger numbers, and when the bandwidth equals 1.0, the binomial and Chebyshev transformers are identical. The Chebyshev coefficients are applied in calculating characteristic impedances for prescribed input and output line impedances. The modification here is inclusion of slow/fast wave velocities to the characteristic impedance. >

An incident field sensor for EMP measurements

The initial development of the balanced transmission-line wave sensor is described. This sensor is being developed to address the need for a directional sensor when dealing with extrapolation issues for hybrid electromagnetic pulse (EMP) simulators. A prototype sensor was designed and tested. It provided good performance with measured front/back ratios between 20 and 29 dB. This may be adequate for many applications. >

Slow wave propagation using interconnections for IC technologies

A new microstrip slow wave transmission line, based on a periodic structure made with the two metallic levels used in ICs, is described. Using on-wafer measurements, an effective permittivity as high as 20 in a wide microwave frequency range is reported. The transmission line has also been measured to obtain the characteristic impedance and the losses. Using the basic periodic structure theory the propagation constant of this media has been computed and good agreement has been obtained with that of the measurement. This slow wave structure is very promising for use in MMIC because of its very compact design.

A Novel Approach to Transients in Transmission Lines

Transient traveling waves in transmission lines can be analyzed by means of bounce diagrams. However, the procedures in deriving the transient responses are often mechanical and provide little physical insight to the solutions of wave equations. In this paper, the incident and reflected waves are described in terms of voltages and currents observed by moving observers. Using the results derived, we present a more logical procedure for the graphical analysis of transient waves using bounce diagrams. The method is general and can be extended to nonuniform transmission lines driven by arbitrary time-varying sources. The relation between voltage and current responses can be represented by means of trajectories in the V-I plane. These trajectories can be logically derived from the transient responses given in the x-t domain.

Chaotic phenomena in acoustic and elastic wave transmission lines

A review of chaotic dynamics in nonlinear oscillators will be given. Evidence for chaotic phenomena in coupled nonlinear oscillators and wave propagation systems will be presented. In particular, large amplitude vibrations in flexible elastic and acoustic vibrations in a cylindrical cavity will be examined. In the latter problem, nonlinear boundary conditions at the end of the tube produce chaotic modulation of an acoustic carrier signal when excited by a deterministic harmonic signal. How higher‐frequency acoustic waves can excite low‐frequency chaotic vibrations of an elastic end plug of the tube will also be shown. New experimental methods for analyzing chaotic dynamics will be discussed, including Poincare maps and fractal dimensions. Speculation on the existence of chaotic waves in other wave systems will be posited. A demonstration of chaotic oscillations will also be presented.

Nanosecond current probe for high-voltage experiments

A matched, slow wave transmission line is used as a current probe. It provides a linear response, fast rise time (τr &amp;lt;2 ns) and high-voltage gain (≂1 V/A) for current pulses up to microsecond duration.

The Elliptical Surface Wave Transmission Line

Electromagnetic wave propagation on an elliptical cross-sectional surface-wave transmission line is investigated theoretically. Characteristic equations for odd and even hybrid modes are derived and solved numerically. Expressions are obtained for power flow, energy storage and power loss using a perturbation method. Numerical results on propagation characteristics of three lower order modes are presented. The /sub 0/HE/sub 11/ mode is shown to have low attenuation particulary at high eccentricities. The propagation characteristics of lines of high eccentricities are found to be slowly varying functions of dimensions.

Research on Wave Phenomena in Hydraulic Lines : 6th Report, Transient Properties of Non-linear Elements

A new method is presented which gives complete plots of transient waves in hydraulic pipes with non-linear boundaries. The numerical procedure of the Laplace inversion plays an effective role there. The availability of the method is confirmed in the experiment to observe dispersions of pressure pulses by an air bubble placed in an oil pipe. This method also makes it possible to experimentally investigate transient flows in a pipe with a circular orifice. The results show that the characteristics of an orifice placed in a transient wave transmission line are approximated by the steady-state ones, if there is no reserve flow at the orifice. Moreover transient variations of flow-rate are measured by a modified "impedance tube" method which is realized by virtue of the present analytical technique. The measurement reveals the hysteresis in the relation between the instantaneous pressure drop across, and flow-rate through, the orifice.

MAGNETIC COATED SMALL DIPOLE ANTENNA

Theoretical calculations and experimental measurements of the basic parameters of coated small dipole antenna were carried out in the short wave range. It was concluded that the resonance frequency of the dipole could be lowered and the radiative resistance could be improved by magnetic coating at the price of some loss in band width and efficiency. The radii ratio of the coating and the inner conductor played a primary role as compared to the absolute size of the magnetic material. In addition, the characteristics of the magnetic coated antenna was explained within the framework of an approximate theory based on surface wave transmission line concepts. The design procedure of such antennas was also discussed.