Amplitude Modulation in Traveling Wave Tube Phase Modulator

Several problems of the amplitude modulation caused by the traveling wave tube used as a microwave phase modulator are discussed. Using Pierce's linear theory, some expressions for phase modulation and the amplitude modulation which occurs simultaneously are derived. From the derived composite modulation formula, various effects of the amplitude modulation on amplitude of carrier and each side band are calculated. To decrease amplitude modulation, experimental studies are performed by using the 1st anode to compensate it and a satisfactory improvement has been obtained

A Theoretical Treatment of the Frequency Entrainment of a Reflex Klystron

The frequency entrainment of a reflex klystron is studied in a fundamental way by setting up the differential equation which describes the oscillation of the klystron cavity under application of an external signal. Under such a condition that the oscillator runs at its normal operation with no electronic susceptance and with matched loading, the problem is shown to be essentially analogous to the simmilar one in an ordinary vacuum-tube oscillator of lower frequency range. Within this limitation on the operation condition the bandwidth of frequency entrainment is estimated in relation to the power ratio of the externally applied signal and the output of the normally operating klystron oscillator. Phase retardation of the cavity oscillation in the entrained klystron from the phase of the externally applied signal is investigated. In connection with this subject, the self-excited oscillation of the reflex klystron is also introductively treated from the standpoint of the theory of nonlinear oscillation

Two-Stage Parametric Amplifier Coupled Through Idler Wave

It is described how a matched parametric amplifier can be obtained if two negative resistance type parametric amplifiers are cascaded so that their idler tanks are interconnected by a quarter wave length transmission line. The analysis of such an amplifier has been carried out and testified by experiment. This type of parametric amplifier has several features besides the matched characteristic at the input and the output terminal, that is, the gain is independent of the phase difference between the two parametric excitations, the sensitivity of gain vs. excitation power is very low and the bandwidth is wider than that of single ones, having a double peak characteristic

Measurements on the Frequency Entrainment of a Reflex Klystron

The bandwidth of frequency entrainment of a reflex klystron was measured in relation to the power ratio of an applied external signal and the output of of the klystron at its normal operation. Measurements were also carried out on the output power of a frequency-entrained reflex klystron both for the various frequency deviations of signal frequency from that of the klystron at its normal operation and for the various power ratios. As a supplement to the theory previously reported by the authors, an analysis is given for the case when the klystron does not operate at the center of an electronic mode in the absence of an external signal. It is shown that the theory is in rather good agreement with the experimental results

Locking Equations for Microwave Circuits

By extending an ordinary admittance expression, the simplified equation for an oscillator has been obtained, which as yet is in the most general form within the first order approximation. Then, this equation has been transformed into the amplitude and the phase equations suitable for analyzing a microwave circuit involving oscillators. It has been found that the amplitude equation can be ignored when the oscillator is adjusted to produce the maximum output power. An example of application has also been given

A Study on Nonreciprocal Parametric Amplifiers

Two or three methods are described to obtain a nonreciprocal parametric amplifier by use of two parametric elements in the frequency inverting case without using nonreciprocal elements such as a uniguide or a circulator. This kind of amplifier can be matched at the input terminal and/or at the output terminal. In a certain case the backward insertion loss can be made infinite. It was proved, however, in regard to the stability criterion that the two properties (matching and infinite backward insertion loss) can not be realized simultaneously. The other characteristics are almost the same as the usual negative resistance parametric amplifier. Some experimental results are presented with respect to one of the amplifiers. Though it has an electrical difficulty of construction, if once built, it may be convenient for low noise pre-amplifier

An Analysis of Traveling-wave Amplification of Surface Magnetostatic Wave

The amplification of a surface magnetostatic wave is analyzed which propagates on the contacting surface of ferrite and semiconductor layers magnetized transversely. A hydrodynamical and collision dominant model is adopted for carriers in the semiconductor. It is explained that neither diffusion effect nor surface charges induced by the Hall effect have to be considered in this case. Maxwell's equation under adequate boundary conditions is solved to give a complex characteristic equation of real ω and complex k. The following results have been obtained from the equation. 1) When the carrier density or the thickness of the semiconductor is small, the amplification factor is proportional to both of them. 2) There is an optimum value of the carrier density or the thickness to obtain the maximum amplification factor. 3) The amplification factor depends on the direction of static magnetic field

Measuring method of loss for optical waveguides by use of a rectangular glass probe

The use of a glass-plate probe of rectangular shape is proposed for the measurement of transmission loss in thin-film optical waveguides. The light-collecting window is of a thin rectanglar shape perpendicular to the light streak, while the conventional fiber probe has a very small circular face. This transversely elongated form results in a great improvement of the mechanical tolerance for the probe movement in the vertical as well as the transverse direction. Theoretical investigation is also presented in reasonable agreement with the experiments