Miniature narrow band filters with high performance can be formed by means of high Q and low temperature coefficient dielectric resonators, such as barium titanate, which are reasonably placed in a cut-off waveguide and properly excited. This paper describes a new type dielectric resonator band-pass filter which can be combined with MIC. At present, this kind of filter is the best one of the filters used in MIC. It has been shown, for example, that a 5 cm band-pass filter using three dielectric resonators with relative bandwidth of 0.2% has an insertion loss of about 0.8 dB, the attenuation outside the band over 50 dB, and the ratio of 30 dB to 3 dB bandwidth approximately 3.3. This filter has been theoretically analysed, and some interesting formulae are derived. The practical measured performances  for 1-to 4-resonator band-pass filters are presented.

In this paper, making use of the rotatory transform, the negative resistance condi-tions of five typical amplifiers are determined. Using the phenomena of combination oscillation existing only in the negative resistance effect, we obtained the results of spreading the oscillatory band and of amplifying the amplitude. Thereby it indicates the fact that there is a third oscillatory type oscillator, between feedback oscillator and negative resistance oscillator which has actual usability.

Based on actual M-sequence autocorrelation function, this paper has formulated the system impulse response function with the method of correlation, given a discussion for the measurement of impulse response function of phase locked loop, derived the mathematical models for major components, with which the measurement was taken,and finally, analysed the frequency spectra for curves actually measured.

In the kinetics of electron cyclotron masers, the method based on the local field expansion in the guiding center frame has many advantages. In this paper, an equil-librium function of electrons applicable to this method is given. The function specifies the space distribution of the electron beam explicitly. On employing this function, a dispersion relation which can compare with that derived in the waveguide axis frame is obtained.

In this paper, the influences of phase difference between two single tubes of dual-TR tube on receiving lose and receiving VSWR in balaneed duplexer are investigated exper-imentally. The experimental results show, if the phase differenee is greater than 30 degrees, then the receiving loss will exceed 0.5 dB and the VSWB will increase correspon-dingly. It shows that the experimental results are comparable with the theoretical calculations.The relation between the phase of individual stage of the three-stage plug-in discharge tube and the phase of the dual-TR tube is investigated. The experimental results indicates that this relation approximately obeys the superposition principle.

The eonversion coefficient of a TWT can be reduced, when it works at under-voltage condition. Therefore if a section of helix which works at under-voltage condition is added to a TWT, the improvement of AM-PM eonversion coefficient can be expected,then a "doubl taper helix technique" is developed.This paper describes the double taper helix technique and presents a small signal design method. The actual TWT which uses the double taper helix proves that it not only raises the electron efficiency, but also improves the AM-PM conversion coefficient. Further experiment shows that this technique has other advantages, such as operation at two or three power levels and good depressed collector characteristics.

This paper suggests a new a scheme for a laser aecelerator according to the principle of geometrie opties. A lens with special non-spherical surface is used to focus the laser rays onto the axis. The phase of these rays can be continuously adjusted as the electrons move forward along the axia, so that the constant acceleration of electrons lis achieved. Because the focusing factor lis very large, the electrons can obtain a very high energy gain on a very short length of travel. When the electrons are decelerated, it is possible to realize a free electron laser. Finally, we prove that it is impossible to use a focusing mirror in this scheme.

Using DC and pulse retarding field methods, we have measured the effect of in-creasing primary electron energy on the secondary emission coefficient of W-Y₂O₃ cermet cathode at room-temperature, and the variation of the first crossover and the maximum secondary emission coefficient (δ_max) from room-temperature to 1500℃, respectively, The secondary emission properties are getting better as the temperature of the cathode rises. δ_max> 7 at 1400℃. The experimental results obtained in magnetrons show that this kind of cathode is good to be used in high power magnetrons at high temperature.