Some computing techniques of the unimoment method for solving electromagnetic scattering problems of a dielectric cylinder with arbitrary cross section are investigated. Rieatti transformation is used in solving the set of linear equations for finding the internal fields inside the mathematical circle and its computer program is realized. With the exam-ple of a rectangular cylinder, automatic generation of finite element mesh realizing Ricatti transformation is illustrated. It is seen that by using the above techniques and methods, effects in saving the memory capacity and the computing time of the computer and in simplifying the previous procedure of the finite element method are obvious; and also the convenience for the formation of a universal computer program is provided.

Higher order modes coupling characteristics in H₁₁^O, circular bending waveguide are analyzed according to the coupled wave equations, and coupling coeffecients of E₀₁^O, H₂₁^O, modes and their amplitudes are computed. A broad-band H₂₁^O, E₀₁^O mode filter has been presented. Experimental results indicated that its practical application is quite satis-factory. Thus, the problems presented by N. Nakajima, etc. can be solved.

The current modulation characteristic of PIN modulator is analyzed, and its highly-nonlinear characteristic appearing on a linear coordinate is discussed. A circuit com-pensation method, in which a logarithmic network is mainly used, is presented for making the modulator linearized. This method shows up satisfactorily in experiment.

Starting from the current-voltage equation given by A. Van der Ziel (1976), a dif-ferential equation of the normalized fluctuation is developed. Expanding the Pourier transform of the fluctuation into a power series in the parameter jω and solving the equation developed, we get all order analytical solutions of the Fourier transform of the fluctuation in drain and gate. The spectral desities of noise current of drain and gate as well as the correlation coefficient are also obtained. The effect of the higher order solutions of the equation on the noise spectra is shown in the conclusion.

A description of a phase-locked loop (PLL) is given, which is successfully used in an X-band linear PM inicrowave source with 6 μs pules width, 30 MHz bandwidth and 1 ms FM pulse cycle. A phase-locked method is used to obtain the linear FM pulse signal with highly stable starting frequency equal to the stability of the 5 MHz crystal oscillator. The operation of the PLL is under a switching mode. Minimum time delay, rapid ability of acquisition, large synchronous range, good signal to noise ratio, simplicity in consturuction and high reliability with higher power output are the advantages of the PLL used. the characteristic and the approach for the realization of the PLL are described also. This PLL has been used in a remote sensing system and high quality results have been obtained.

A computer program for calculating emission current in an electron gun has been worked out, and good agreement between calculations and experiments has been achieved. The computation model is based on the statistical theory of thermal electron emission, and the potential distribution in front of the cathode is equivalent to that o f an infinite planar diode in which the effect of the longitudinal thermal velocity of electron (ELTVE) is included.It is shown by the computation:1. In the case of CRT, the ELTVE must be taken into account. The calculated currents are greater than that estimated by the 3/2 power law and are closer experimental results than in the latter case. 2. In high density gun, the ELTVE is noticeable when it works at low voltage, but on the whole it is much smaller than in a CRT gun. 3. The ELTVE becomes significant as the difference between the operating current density and the cathode loading limit increases, and the effect remains unchanged when thedifference is beyond a certain value.

A basic principle of spiral strip line generator (SSLG) for obtaining millimicrose-cond pulsed high voltage is described. Design method of SSLG with a short switch is given. The SSLG s inner end is the high -voltage output end, and its outer end is grounded. The working parameters and main geometrie sizes of SSLG designed for portable X-ray generator, are also given. Fabricating technology of SSLG is described in detail. Electrical properties of the generator are investigated experimentally. The generator, when connected with X-ray tube, can yield 40--70μR of X-ray radiation at 1 m from output-window of the X-ray tube.

An investigation of the working state of the ignition type thermionie energy con-verter (TEC) is carried out and a physical model is established for analysis and calcu-lation. The region between the positive and the negative electrodes is divided into five sub-regions: Positive and negative sheathes, positive and negative transition sub-regions and a neutral plasma sub-region. An analytical study of the ionization mechanism in the TEC, a calculation of voltage-current characteristic and the distribution of plasma parameters between electrodes are described from a physical point of view. It is shown that ionization in the TEC is mainly determined by the step-type ionization. Plasma parameteres are characterized by means of the one-dimensional electron flow and ion flow transport equation, the continuity equation and the energy transfer equation, while the complicated transition regions near the electrodes are considered as boundary conditions as an approximation. The theoretical analysis and numerical calculations indicate that this analytical method is applicable.

The formula and program for calculating the total and negative first harmonie interaction impedance from the data of "large perturbation measurement" are given. This program is a part of the programs for CCTWT design.