In this paper, the boundary element method (BEM) and the finite element method (FEM) are compared. Then the formulation of Helmholtz equation by BEM and the ealeulation of the reflection coefficient for step-open parallel plate waveguide by BEM are presented. Finally the flow-chart of the program and the computed results are given. Comparison of the computed results for the standing wave state with those given by the related literature shows that the computed results are reasonable.

Dvadic Grcen s function is useful for solving the boundary problems in electromagnetic theory. The key problem involved is how to deal with the additional term in the electric dvadic Green s function in the source region. In this paper, dyadic Green s functions for generalized cylinders in free space are derived with the technique given by the author (1984). The dyadic Green s functions for perfectly conducting wedges, half-planes and elliptic cylinders, whose integrals of continuous spectral h have been elliminated, are given particularly.

A diagraph associated with an indefinite matrix is augmented. Both first-order and second-order cofactors can be obtained by finding all the directed trees in the augmeuted diagraph, and then, the need of computing the directed 2-trees for the second-order cofactors is eliminated. The method proposed here is particularly applicable to computer-programming.

Rational harmonic injection locking (RHIL) can make the whole circuit simpler and more flexible than harmonic injection locking (HIL) does. A common formula of the synchronizing band △ω_(s/m)max of the RHIL is derived and aualysed in this paper. Itshows that the formula of the synchronizing band of HIL given by I. Schmideg (1971) is a special case.A method which is used to expand the RHIL s synchronizing band with full-pass network, is presented. With this method, a 2/3 injection-locking VHF divider made of IC FZIC is developed. Its stability factor n=Δf_(3/2)max)/Δf_{[-40—+85℃]}≥4. For the original circuit, n≈0.6. It makes the RHIL of better practical value.

Based on the understanding of the fundamentals of PLL, several different opinions about some problems in the paper-"A Quantitative Research of Nonlinear Behaviour of a Second-Order Phase-Locked Loop by Perturbation Method" are presented.

In this article, the operation of the current switching multiplicator is quantitatively analyzed in some detail. The relatiors between the optimum operation-state and the parameters of circuit elements in the multiplicator are given.Furthermore the principle of optimum design is derived and proved experimentally.In addition, the stabilitv of the differential inductor and the parasitic harmonic effect on the frequency stability of multiplicator output signal is also discussed.

In this paper, a computer program is made for studying actual parametric amplifiers with Hi-lo doping varacters. The main parameters of the parametric amplifier, e.g. working frequency, bias voltage, pumping power and negative resistaaee are obtained with this program, then a basis for the desiga of paramatric amplifiers is provided.

A modified conventional RF sputtering equipment was used in preparing the Al₂O₃ antireflectrve coating (ARC). An increase in the light power output of 30-66% at a driving current 200 mA for the GaAs/GaAlAs DH LEDs coated on light emitting surface with ARC thickness of about λ/4 has been obtained. In the same case a light output increase of less than 30% for these degraded LEDs has been determined. It may probably be attributed to the defects formed in the bulk of the Ga_1-xAl_xAs crystals caused by degradation of diodes restrict the increase of light output.

This paper proposes simple method for measuring the admittance of the inclinedslot on H-plane of rectangular waveguide of a slot array, and the measured results are given.

Discussions in the problem of cut-off phenomenon of the waveguide was made by many authors. In this paper, we make a comparison between the cut-off phenomenon of waveguide and the quantum mechanical tunnel eff ect. The significant result is presented.

The negative electric effects of La metai at the Si/SiO₂ interface and the heat treatment behaviour of these effects are studied experimentally. In addition, the results of electron spectroscopy analysis of the La-doped interface are also presented.