Surface acoustic wave components have been realized which perform the functions of transduction, amplification, and coupling. Applications are suggested which make use of these components. Exploratory work in connecti...
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Surface acoustic wave components have been realized which perform the functions of transduction, amplification, and coupling. Applications are suggested which make use of these components. Exploratory work in connection with surface acoustic waveguides suggests the feasibility of acoustic analogs of conventional microwave transmission line (microsound) components on the surface of crystal and substrates. These microsound transmission lines, hybrids, and directional couplers interconnect microsound transducers, amplifiers, isolators, and phase shifters to form microsound circuits capable of autocorrelation, Fourier transformation, and cross correlation functions. Compatible component configurations are proposed and evaluated which perform these basic functions. The anticipated difficulties with their realization are discussed and the current status of critical problems including the epitaxial growth of thin films and submicron etching procedures will be given. Several circuits capable of performing correlation functions are given.
Review of the Subject.—In high-voltage power circuits, such as transmission lines and the high-voltage coils of large power transformers, not infrequently disturbances are observed of a frequency differing from, and ...
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Review of the Subject.—In high-voltage power circuits, such as transmission lines and the high-voltage coils of large power transformers, not infrequently disturbances are observed of a frequency differing from, and usually very much higher than that of the power supply, and differing from the typical transient of energy readjustment, in that they do not gradually die out, but increase in intensity until either destruction occurs, or they finally limit themselves. Such cumulative oscillations or arcing grounds derive their energy from the machine power of the system, and so constitute a frequency transformation, of which the mechanism has been little understood. Physically they may be derived from the typical condenser discharge by the conception of a negative resistance, in combination with a source of power, which supplies the energy given out by the negative resistance. Attention is drawn to a class of conductors—to which arcs and gas discharges belong—the so-called “third-class conductors,” in which the voltage decreases with increase of current, and it is shown that these conductors can be considered as a combination of a negative resistance with a source of power, and as such are capable of transforming the low machine frequency into a high oscillation frequency of alternating currents, and their presence in an electric system thereby may produce cumulative oscillations. The general equations are then derived of a system comprising a third-class conductor shunted by an inductive circuit containing capacity, and supplied with voltage over an inductive circuit from an alternating low-frequency source, and it is shown that in such a system currents and voltages of two distinct frequencies may continuously exist, of which the one is the machine frequency, the other a high oscillation frequency. It is further shown that the voltage of the latter is limited only by the resistance of the oscillating circuit, and in low-resistance circuits may build up to very high va
Summary form only. An abstract of the above-titled article, taken from the 1963 IEEE International Convention (held March 25-28, New York, NY, USA), is presented.
Summary form only. An abstract of the above-titled article, taken from the 1963 IEEE International Convention (held March 25-28, New York, NY, USA), is presented.
The design of certain log-periodic microwave circuit elements requires a knowledge of the characteristic impedances of a system of four-coupled strip transmission lines. The system of four strip conductors between par...
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The design of certain log-periodic microwave circuit elements requires a knowledge of the characteristic impedances of a system of four-coupled strip transmission lines. The system of four strip conductors between parallel ground planes is capable of supporting four different TEM modes which have different characteristic impedances. In this paper, the characteristic impedances of the four modes are determined by a variational method. The variational solution is an upper bound to the exact characteristic impedance of the line. In general, the coplanar strip conductors are located at an arbitrary (but identical) displacement from the parallel ground planes. When the separation between the broadside-coupled strips is precisely one-half the spacing between the parallel ground planes, two of the mode impedances may be determined exactly by means of conformal mapping. The variational solutions are compared to the exact solutions for this special case. Because of the "cell image" principle which holds for the problem, the mode solutions presented here also apply to various single- and two-conductor strip transmission lines with arbitrary displacements. As a result, solutions for the following strip line configurations are available from the analysis: a single strip conductor in a trough, or between parallel ground planes; two coplanar strips between ground planes; two broadside-coupled strips in a trough, or between parallel ground planes. An extensive set of curves are presented which show the characteristic impedances of the four modes as a function of the relative dimensions of the strip transmission line.
A new lumped-circuit directional coupler is described for the 1-30 MHz frequency range. Directivity greater than 50 dB is achieved over this frequency range for coupling ratios of 30, 40, and 50 dB. Greater directivit...
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A new lumped-circuit directional coupler is described for the 1-30 MHz frequency range. Directivity greater than 50 dB is achieved over this frequency range for coupling ratios of 30, 40, and 50 dB. Greater directivity can be achieved over a narrower frequency range, and the coupler can be tuned for essentially infinite directivity at a fixed frequency. The couplers, although resistive, can pass 100, 300, or 1000 watts for the coupling ratios of 30, 40, and 50 dB, respectively, with less than a 0.01-dB change in coupling ratio. The coupling ratios are constant with frequency to ±0.25 dB. Equations and curves are given for obtaining component values needed to design a resistive-divider-type coupler with any coupling from 3 to 60 dB.
The practical difficulties encountered in commercial operation of short-wave transmitters, due to the great number of radio-frequency stages required for crystal control, are summarized. The objections to crystal cont...
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The practical difficulties encountered in commercial operation of short-wave transmitters, due to the great number of radio-frequency stages required for crystal control, are summarized. The objections to crystal control for some transmitters operated on frequencies above 35,000 kilocycles are given. Methods are described for meeting these objections through frequency control by long radio-frequency transmission lines, which have inherently large volt-ampere capacity and which make possible a considerable reduction in operating costs and improvement in reliability. Methods for applying the lines to the control of oscillator frequencies by using them as relatively constant low power factor resonant circuits and as aperiodic means for feeding regenerative energy from anode circuits to grid circuits are described. A method is given for obtaining both the advantages of crystal oscillators as frequency standards and the economies and reliability of long line transmitter frequency control. Applications of the methods described to experimental and commercial transmitters are mentioned.
The Hanford system for measurement of neutron time of flight differs from conventional techniques only in the use of a vernier chronotron for time interval measurements. The chronotron consists of two circulating tran...
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