Making use of the perturbation approach, the large-orbit electron cyclotron maser is investigated. The perturbed motion of clectron and dispersion equation are obtain-ed, where gyrotron and gyro-peniotron are included. Then some discussions are car-ried out.

The general solution of the boundary value problem of the electromagnetic field in a regular boundary condition is got by moment method, then the general form of the dyadic Green s function is derived in this paper. By the moment method not only the regular boundary condition problem of electromagnetic field can be solved, but also some electromagnetic fields in complex systems may be solved.

This is the first part of our work on the dyadic Green s functions (DGF) at the souree region in circular waveguides. In this paper, a systematic and nevel approach is developed for the dyadic operation of DGF. The complete farms of the dyadie operation of DGF for circular waveguides are given. Ambiguities associated with the dyadic operation in the literature are clarified and the errors are redressed.Contrary to Kisliuk (1980, 1983), it is shown that the expansion of the longitudinal vector eigenfunctions L and the expansion ofthe transverse vector eigenfunctions M and N are not purely lognitudinal and transverse fields at the source region. In addition, it is also shown that the interchanging differential and integral operators to carry out the dyadic operation of DGF is invalid at the source region (Tai, 1973).

In a complex filter which is realized by using a wave digital lattice filter, the relation between the real part and the imaginary part of its output fulfills Hilbert transformation. A novel simple algorithm for this kind of Hilbert transformation is given. The design formulas and process are so simple that a pocket programmable calculator or a microcomputer is suffieient to carry out the necessary calculations.

An analytic solution of distributed matching network with maximum flat characteristic and any desired slope is presented. The result can be used for designing microwave multioctave tran-sistor amplifiers.

A detail discussion on multistate technique and a comparison of it with the multiport technique are given. The relation between output powers and reflection of the device under test is shown. An experjmental millimeterwave multistate reflectometer is given and its measuring nesults are satisfactory.

Asenic ions are implanted with doses of 5×10^11—5×10¹⁵ cm^-2 into LPCVD polysilicon films o nSiO₂ substrate, which have been recrystallized with CW Ar⁺ laser before implantation. Electrical measurements show that its resistivity is lowered and its mobility is inereased significamtly at low doping concentration (10¹⁷ As⁺cm^-3). Plasma hydrcgen annealing is performed on laser recrystallized samples. The electrieal character is ics of plasma hydrogen annealed samples are close to that of single-crystalline silicon. Based on the existing theoretical modelsforconduction in polysilicon, a new formula for large grain polysilicon has been proposed, with help of which a good agreement between the theory and experimental results is achieved in the range of doping concentration from 10¹⁶cm^-3 to 10²⁰cm^-3.

The impregnated barium scandate dispenser cathode used in microwave tulbes, especially in gyrotrons, has been investigated in following aspects: (1) pulse emission property and work function distribution; (2) electron initial velocity distribution in pulse operation; (3) the effect of pulse duration ratio; (4) anomalous Schottky effect under high electric field. Some useful results are obtained: the pulse emission current density is higher than 20 A/cm² (when t=850℃) ; the anomalous Schottky effect is observed when the electric field is higher than 10⁴V/cm; the cathode has a flat J_a-fτ property when the pulse duration ratio is in the range of 5×10^-3--4×10^-2 and an emission current density of 8.8A/cm² is drawn. In the end, the obtained results are discussed in relation to the surface analysis of the cathode.

A set of computation formulas of discrete cosine transform (DCT) for image data eompression is given. The results of simulation experiment show that the formulas are correct and consistent with the formulas given by W. K. Pratt (1978), but they are different slightly in form.

A new method is presented for extending the operation frequency bandwidth of corrugated horns by using the negative admittance region, and it is verified by experiments.

A continuous-time equivalent without frequency dependent elements for analysis of SC networks is derived by using the mixed bilinear-LDI transformation.

The discrete time detection of Swerling Ⅱtargets in Rician clutter is investigated. The likelihood ratio (LR) detector struetures when the clutter steady component is coherent and noncoherent are developed respeetively. The efficacy expressions for the detectors are derived. The calculation results show that the more the clutter statistics depart from the Gaussian situation, the better is the detection performance of LR detectors than that of square law detector. The ARE in case of clutter steady component being coherent can be more than twofold higher than that in case of clutter steady component being noncoherent.

A kind of PbTiO₃ piezoelectrie ceramies modified with (Pb_1/2 Ni_1/2)MnO₃ is recommended. It possesses fine VHF performances. Its coupling factor K_t is 0.48; mechanical quality factor Q_M is high; and frequeney stability is good.With the above mentioned material, "We have assembled a 62 MHz band-pass filter which consists of seven vibrators. Its stop-band attenuation reaches 30 dB; insertion loss is 6 dB; the ripple ratio of pass band is 0.5 dB; while the rectangular ratio is 3.4.The depolarization phenomenon appearing in this kind of PbTiO₃ ceramics is discussed. It is proposed howto overcome the depolarization phenomenon. And it is thought that this kind of ceramics may be an ideal material for developing PbTiO₃ surface wave devices.