Terminals Of Transmission Line Research Articles

Derivation of the transmission-line equations from linear-antenna theory

Establishes, by means of an integral equation, a relationship between antenna and transmission-line theory. In the interest of brevity some of the notation employed is set forth in a figure depicting a terminated transmission line, or alternatively, an end-loaded folded dipole.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analysis of noise, speed and dynamic range of fast low-noise preamplifiers for termination of transmission lines

Different configurations of very fast preamplifiers based on BJTs and capable to operate as active cable line terminators are considered in this paper. The design of such preamplifiers allows one to put the front-end out of radiation “hot” areas and solves the problem of radiation resistant electronics. Noise performance, dynamic range and dependences of gain and input impedance on frequency are computed using the PSPICE 5.0 program.

Experimental modelling of high frequency circuits at low audio frequencies part I

At microwave frequencies, frequent use is made in circuit design of the electrical properties of short lengths of resistively terminated transmission line. It will be shown in the following contribution that circuits based on high frequency distributed lines can usefully be modelled at low audio frequencies using lumped element lines.

Digitally adjustable resistors in CMOS for high-performance applications

Methods by which CMOS circuits can be adjusted digitally to generate controlled impedances for use in high-performance circuits are described. Since digital signals are the only inputs to these circuits, on-chip DC power dissipation can be reduced, the circuit can be made more robust, and the impedance of the circuit can be adjusted by manipulating the input digital information. A design of a CMOS series terminated line driver is discussed, and the utilization of the controlled impedance in terminating transmission lines on-chip, constant delay lines, and controlled di/dt output buffers is discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Prevention of transient voltage instabilities due to induction motor loads by static VAr compensators

The application of static VAr compensators (SVC) to prevent transient voltage instability due to the presence of large induction loads at the terminals of long transmission lines is discussed. Eigenvalue analysis is used to identify the conditions for voltage instability. The analysis is supported by transient time simulations for the complete power system following large disturbances. It is found that SVC can obviate transient voltage instabilities and maintain the load voltage near its rated value. It is shown that replacing the SVC with mechanically switched capacitors may not provide stabilization owing to the time delays associated with voltage drop detection and breaker operation. >

A new GaAs power MESFET structure for improved power capabilities

A GaAs microwave power MESFET structure is described that achieves a significant improvement of the gate mode attenuation by incorporating a suitably terminated transmission line parallel to the gate. The reduced attenuation allows a much wider single gate (a factor of 4 is possible) and a corresponding improvement of the total output power. It is shown that this approach leads to higher gain and cutoff frequency. An additional advantage of this MESFET structure is its higher input resistance relative to a device with equal total gate width but more gates in parallel. This results in simpler matching circuits of greater bandwidth. The single-gate structure can be connected in parallel to further increase the total output power. The results of an electrical characterization of the devices are presented, and its advantages and potential application are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Heterojunction Ohmic Contacts to Si Using Ge/Si n+/n+ Structures

ABSTRACTOhmic contacts to n-type Si have been formed using a thin n layer of Ge grown by selective-area molecular beam epitaxy. The n+Ge is used to lower the metal-semiconductor barrier energy and thus reduce the contact resistivity of the thin film structure. Al/n+Ge/n+Si test devices were fabricated in a manner compatible with conventional VLSI processing and consisted of a 3500 A thick layer of arsenic-doped Ge grown at 250°C on a selectively diffused, phosphorus-doped Si substrate. Using both four terminal Kelvin and transmission line devices, unsintered Al/Ge/Si structures exhibited contact resistivities a factor of five lower than Al/Si control devices, in agreement with theoretical calculations based on a simple tunneling model for the metal/Ge/Si heterojunction ohmic contact.

Switching Surge Characteristics Of Six-Phase-Transmission Lines

Transient switching overvoltages are important to both terminal equipment and transmission line design. In addition to phase-ground surges, phase-phase surges are particularly significant in comp three-phase and high phase order line design.

Analysis of transmission-line signal distribution to multiple ports

The frequency response of a characteristically terminated transmission line, with multiple lumped discontinuities (output port loads) along the line, is determined. The analysis applies steady-state transmission-line solutions and simple circuit analysis methods in an iterative manner to determine the frequency response of each output port. This method is applied to the case of equally spaced capacitive reactance impedances along the transmission-line length. The phase and amplitude distortion resulting from line losses and output loading are determined.

Transients on lossless terminated transmission lines

This work contains a general exposition of the methods which are available in analyzing the transients on a lossless terminated line. After reviewing the well-known method based on the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Gamma</tex> -series expansion, we present two alternative methods: one in the form of a Volterra integral equation, and another corresponding to the so-called singularity expansion method. For a resistively terminated line, we have proved the identity between the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\Gamma</tex> -series solution and the one obtained by the singularity expansion method. The application of these methods to more complicated terminations is illustrated by the case of a series RL termination. Weber's solution for a short-circuited line is compared with our solution. The importance of injecting the causality condition in our formulation for this class of problems is emphasized. The application of these methods to the treatment of the input current response of a thin biconical antenna is briefly outlined.

Parametric behavior of the dynamic period overvoltage on power transmission systems

A physical understanding of the dynamic period response of transformer terminated transmission lines is developed using a simplified single phase lumped model and time domain analysis. The sensitivity of the response to various circuit parameters is predicted based on this analysis and then verified using numerical techniques. Results are extended to three phase systems through studies performed on an analog transmission system simulator. It is shown that a weak source is the major factor leading to the generation of a dynamic period overvoltage.

Determination of Overvoltages in Transmission Line Terminations Using a Physical Model

Switching transients have been studied for a short line terminated by an inductor. Resonance with the third harmonic of the transient voltage in the line can produce a peak of 5 pu in the termination, while the fifth harmonic can produce 4.2 pu. Source inductance reduces these voltages appreciably.

Design, construction, and performance of full-range Walsh-type omnidirectional, coherent loudspeakers

The basic design considerations for very high-power, full-range electrodynamic motor structures and terminated transmission line cones are outlined. Certain novel materials and techniques used in the construction of these assemblies are described and demonstrated with photographs and cutaway components. Results of propagation velocity, frequency amplitude, dispersion, and impulse measurements are shown. The measured performance of the Walsh-type loudspeaker is compared with the other major types of wide-range reproducers. The superiority of the Walsh device in waveform retention and coherent wavefront synthesis is demonstrated. The use of the Walsh coherent-sound loudspeaker in applications requiring very accurate acoustic waveform generation in both audio and ultrasonics is discussed.

Studies of Impedance in Cardiac Tissue using Sucrose Gap and Computer Techniques: II. Circuit Simulation of Passive Electrical Properties and Cell-to-Cell Transmission

The impedance measured in a strip of heart tissue from the moth Hyalophora cecropia is fitted by circuit models of several configurations. The circuits include: (a) a single R-C circuit (b) a double R-C circuit (c) terminated transmission lines, and (d) a pattern of cells with cell-to-cell transmission paths. The last of these is found to give the best fit. Calculation of the model impedances and optimization of element values are performed by a computer. The possibility that the mechanism of cell-to-cell transmission may be capacitative rather than conductive is explored using values of capacitance derived from the circuit models to calculate the effect of capacitative coupling alone on signal transmission. The calculations show that sufficient voltage can be transmitted from the excited cell to an adjacent cell to effect excitation.

Distributed theory for microwave bipolar transistors

A transistor large enough in one dimension to span a length significant compared to a quarter wavelength within the device can be treated as two-coupled transmission lines. The general solution of such lines is applied here for the small-signal linear case treated as a classical boundary value problem of TEM waves on coupled lines, which are uniform but have no other restrictions regarding transmission line parameters, coupling, symmetry, similarity, or terminations. This solution is extended to include the parasitic inductance and capacitance usually present in connecting the device into a circuit. Electrical characteristics of a distributed device begin to deviate noticeably from those of the equivalent lumped device even at a relatively short electrical length. Computer simulation of a large distributed transistor indicates that, if properly employed, distributed effects in small-signal operation may lead to advantageous characteristics such as in device impedance levels, stability, and gain-band product. Other characteristics may prove to be disadvantageous or troublesome in large signal or class C operation. If unrecognized or ignored, distributed effects can result in highly unsatisfactory transistor operation. As microwave transistors increase in size and frequency capability, distributed effects will undoubtedly need to be taken increasingly into account.

Signal, Noise and Resolution in Position-Sensitive Detectors

An analysis is presented of signal, noise and position resolution relations for some of the most interesting position-sensing methods. Electronic cooling of delay line terminations is introduced in order to reduce noise in the position-sensing with delay lines. A new method for terminating transmission lines and for noiseless damping which employs a capacitance in feedback is presented. It is shown that the position resolution for the charge division method with resistive electrodes is determined only by the electrode capacitance and not by the electrode resistance, if optimum filtering is used.

Transient Response of an Asymmetric Cylindrical Antenna

The time-domain transient response of a thin dipole antenna is discussed in terms of element lengths and the surge impedances of the transmission line and element terminals. Theory and measurements show that, unlike symmetric configurations, asymmetry in the element lengths, together with appropriate mismatch of the transmission line, produces radiation proportional to the first time derivative of the signal voltage, and replica reception proportional to the incoming field.

Response of a Terminated Transmission Line Excited by a Plane Wave Field for Arbitrary Angles of Incidence

An analysis to determine the response of an impedance-loaded transmission line configuration excited by a plane-polarized electric field of arbitrary spatial orientation has been needed for a long time. The purpose of the present paper is to meet this need by suggesting a method of solution based on the analysis of the simplest of such circuits: an impedance-terminated two-conductor transmission line. The theory is based on the use of the Rayleigh-Carson reciprocity theorem.

Nonlinear Termination of Transmission Lines

The technique of using nonlinear resistances to terminate interconnecting transmission lines has been designed and tested, and is recommended for use in very high-speed digital circuits. This technique can save power, simplify wiring, and eliminate the problem of ringing in branched networks. Line matching by nonlinear resistance is investigated theoretically, and the properties, possibilities, and limitations of this method are discussed. Schottky diodes are recommended for this purpose.

On natural frequencies of a terminated transmission line with feedback

This correspondence describes three results concerning the natural frequencies of transmission lines. It is shown that 1) a transmission line can be terminated in an admittance whose real part is negative in the entire right half of the s plane-yet no natural frequency is in the right half of the s plane; 2) for capacitive termination and simple gain feedback less than unity, all natural frequencies are purely imaginary; 3) for capacitive termination and simple feedback gain greater than unity, exactly two of the natural frequencies are real, one being positive, the other negative. The utility of these results in stability analysis is shown.