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1989 Vol. 11, No. 2
Display Method:
1989, 11(2): 113-120.
Abstract:
In view of K-fault testability, the topological construction of a practical circuif is far from ideal. In order to improve the testability of a circuit, it is used to increase the number of accessible nodes or to use multi-excitation method. Effectiveness of these methods and feasibility choosing accessible nodes arc discussed in detail. The conditions for multi-excitation testability are presented.
In view of K-fault testability, the topological construction of a practical circuif is far from ideal. In order to improve the testability of a circuit, it is used to increase the number of accessible nodes or to use multi-excitation method. Effectiveness of these methods and feasibility choosing accessible nodes arc discussed in detail. The conditions for multi-excitation testability are presented.
1989, 11(2): 121-128.
Abstract:
An injection-locked divider (ILD) can provide good synchronization at lower input signal to noise ratio, which is its advantage over other types of divider. The general expression of phase equation and equivalent model are presented for the ILD with an input additive noise. In the absence of noise the performance of the phase-modulated signal through the ILD and synchronous ranges of the ILD are given. The effects of the additive noise on the ILD are discussed. The injuction-locked amplifier (ILA) is only a particular case in which n=1, therefore the given results are applicable to the ILA.
An injection-locked divider (ILD) can provide good synchronization at lower input signal to noise ratio, which is its advantage over other types of divider. The general expression of phase equation and equivalent model are presented for the ILD with an input additive noise. In the absence of noise the performance of the phase-modulated signal through the ILD and synchronous ranges of the ILD are given. The effects of the additive noise on the ILD are discussed. The injuction-locked amplifier (ILA) is only a particular case in which n=1, therefore the given results are applicable to the ILA.
1989, 11(2): 129-137.
Abstract:
The properties of a nonlinear transfer function are studied. The new ideas of nth-order .stability, nth-order zero-pole point, nth-order frequency response and nth-order sensitivity as well as a new theory and implementation on sensitivity of nonlinear circuits and systems are proposed.
The properties of a nonlinear transfer function are studied. The new ideas of nth-order .stability, nth-order zero-pole point, nth-order frequency response and nth-order sensitivity as well as a new theory and implementation on sensitivity of nonlinear circuits and systems are proposed.
1989, 11(2): 138-146.
Abstract:
The eigenfunction expansion of Green s function and the transmission matrix technique are employed for the computer-aided optimum design of bandpass filters with dielectric resonators based on the planar circuit theory The computed results are in good agreements with the experimental ones.
The eigenfunction expansion of Green s function and the transmission matrix technique are employed for the computer-aided optimum design of bandpass filters with dielectric resonators based on the planar circuit theory The computed results are in good agreements with the experimental ones.
1989, 11(2): 147-154.
Abstract:
The general formulas of characteristic equation and equivalent wall admittance of corrugated horn having N-slot structure are derived by using the space-harmonic analysis method. As a special example, the expression for equivalent wall admittance of corrugated horn having dual depth combination is presented. The equivalent wall admittance, eigenvalues, mode coefficients on horn aperture and radiation patterns have been computed fora corrugated horn having dual depth combination. The calculated radiation patterns are in good agreement with the measured values.
The general formulas of characteristic equation and equivalent wall admittance of corrugated horn having N-slot structure are derived by using the space-harmonic analysis method. As a special example, the expression for equivalent wall admittance of corrugated horn having dual depth combination is presented. The equivalent wall admittance, eigenvalues, mode coefficients on horn aperture and radiation patterns have been computed fora corrugated horn having dual depth combination. The calculated radiation patterns are in good agreement with the measured values.
1989, 11(2): 155-163.
Abstract:
Mutual coherence function for lateral pulse wave in radio communiction in the weak fluctuating random media, by means of assuming that the refracitive-index fluetuation in the random media is of Gaussian spectrum and excited soure is pulse dipolc, is investigated by using Born approxiamation and dyadic Green s function method, and the analytical solution for mutual coherence function is obtained and represented by reflective coefficients, impedence and admittance terms, and generalized hypergeometric series etc. The results reveal that the main contribution to the mutual coherence function comes from coherence field, and the contribution of incoherence field can not be neglected.
Mutual coherence function for lateral pulse wave in radio communiction in the weak fluctuating random media, by means of assuming that the refracitive-index fluetuation in the random media is of Gaussian spectrum and excited soure is pulse dipolc, is investigated by using Born approxiamation and dyadic Green s function method, and the analytical solution for mutual coherence function is obtained and represented by reflective coefficients, impedence and admittance terms, and generalized hypergeometric series etc. The results reveal that the main contribution to the mutual coherence function comes from coherence field, and the contribution of incoherence field can not be neglected.
1989, 11(2): 164-175.
Abstract:
A new method for solving electromagnetic field boundary value problem is given. By using this method, the boundary value problem of vector wave equation can be transformed Into two independent boundary value problems of scalar wave equations and other two additional vector differentia! operations. All the dyadic Green s functions got by eigenfunction expansion of dyadic Green s functions can be got by this method easily and some of the dyadic Green s functions for complex system which are very difficult to get by ordinary method have been got by this new method. The dyadic Green's function for a dielectric loaded cavity is one of the given examples.
A new method for solving electromagnetic field boundary value problem is given. By using this method, the boundary value problem of vector wave equation can be transformed Into two independent boundary value problems of scalar wave equations and other two additional vector differentia! operations. All the dyadic Green s functions got by eigenfunction expansion of dyadic Green s functions can be got by this method easily and some of the dyadic Green s functions for complex system which are very difficult to get by ordinary method have been got by this new method. The dyadic Green's function for a dielectric loaded cavity is one of the given examples.
1989, 11(2): 176-182.
Abstract:
The dyadic Green s functions for perfectly conducting circular cones are derived by means of the operator method and the theory of distribution of dyadic operation, ft is shown that the electric and magnetic dyadic Green s functions given satisfy the basic dyadic equations.
The dyadic Green s functions for perfectly conducting circular cones are derived by means of the operator method and the theory of distribution of dyadic operation, ft is shown that the electric and magnetic dyadic Green s functions given satisfy the basic dyadic equations.
1989, 11(2): 183-190.
Abstract:
The Ca behavior of an impregnated cathode is studied with enhanced diffusion of Ca to the cathode surface induced by low pressure oxygen, and the changes of surface composition are analysed with AES and the method of surface accumulation. The experimental results show that: (1) a significant part of Ca exist in metallic form in the near surface region of the active material in the pores of impregnated cathode ; (2) the diffusion rate of Ca to the surface is proportional to the O2 exposure quantity and the cathode temperature, the activation energy of Ca surface diffusion enhanced by O2 is about 1.34eV; (3) one of the reasons of emission decay under oxygen effect may be considered due to the increase of calcium oxide on the cathode surface, and the one of principal mechanisms of the seactivation is the high temperature cleaning process of the Ca by evaporation.
The Ca behavior of an impregnated cathode is studied with enhanced diffusion of Ca to the cathode surface induced by low pressure oxygen, and the changes of surface composition are analysed with AES and the method of surface accumulation. The experimental results show that: (1) a significant part of Ca exist in metallic form in the near surface region of the active material in the pores of impregnated cathode ; (2) the diffusion rate of Ca to the surface is proportional to the O2 exposure quantity and the cathode temperature, the activation energy of Ca surface diffusion enhanced by O2 is about 1.34eV; (3) one of the reasons of emission decay under oxygen effect may be considered due to the increase of calcium oxide on the cathode surface, and the one of principal mechanisms of the seactivation is the high temperature cleaning process of the Ca by evaporation.
1989, 11(2): 199-203.
Abstract:
A new method is demonstrated for solving the electromagnetic scattering problem of a radially inhomogeneous loss less or lossy dielectric cylinder by Fcurier series expansion. Comparing with other methods, the method is simpler in numerical calculation and can be used for solving scatterng problem of a cylinder due to an arbitrary incident electromagnetic beam.
A new method is demonstrated for solving the electromagnetic scattering problem of a radially inhomogeneous loss less or lossy dielectric cylinder by Fcurier series expansion. Comparing with other methods, the method is simpler in numerical calculation and can be used for solving scatterng problem of a cylinder due to an arbitrary incident electromagnetic beam.
1989, 11(2): 204-208.
Abstract:
Mutual energy formula is used in the theory of expansion of radiation field in plane waves. The differences of transmissive wave and evanescent wave in orthogonality are discussed. The formula for expansion of plane waves with a known current distribution has been given. A problem to determine the inner field of an area in which the tangential fields of partial border have been known has been solved.
Mutual energy formula is used in the theory of expansion of radiation field in plane waves. The differences of transmissive wave and evanescent wave in orthogonality are discussed. The formula for expansion of plane waves with a known current distribution has been given. A problem to determine the inner field of an area in which the tangential fields of partial border have been known has been solved.
1989, 11(2): 209-214.
Abstract:
Based on the polarization current integral equation with the modified Green s function as kernel, the scattering properties of the E-plane uniform dielectric posts in rectangular waveguides are numerically analyzed by moment method. These posts are of arbitrary in cross-stction and post-number. The calculation accuracy and speed are remarkably improved by segmentating the dielectric region into many small rectangular cells and applying local analytic integration. The higher-order modes are considered in calculation. It improves the computation accuracy and can provide the scattering information of all excited modes.
Based on the polarization current integral equation with the modified Green s function as kernel, the scattering properties of the E-plane uniform dielectric posts in rectangular waveguides are numerically analyzed by moment method. These posts are of arbitrary in cross-stction and post-number. The calculation accuracy and speed are remarkably improved by segmentating the dielectric region into many small rectangular cells and applying local analytic integration. The higher-order modes are considered in calculation. It improves the computation accuracy and can provide the scattering information of all excited modes.
1989, 11(2): 215-220.
Abstract:
A 6 mm power combiner which consists of four Gunn diodes with bi-source arrays in rectangular wavegide is described. The operating principle, configuration, optimal calculation, performance characteristics (e.g. combining efficiences, pushing figure, frequency drift and power stability) and experimental methods of the combiner are presented. The theory and technique are suitable for the power combiner operating in centimeter or millimeter wave.
A 6 mm power combiner which consists of four Gunn diodes with bi-source arrays in rectangular wavegide is described. The operating principle, configuration, optimal calculation, performance characteristics (e.g. combining efficiences, pushing figure, frequency drift and power stability) and experimental methods of the combiner are presented. The theory and technique are suitable for the power combiner operating in centimeter or millimeter wave.
1989, 11(2): 221-224.
Abstract:
Secondary emission properties of impregnated barium scandate dispenser cathode has been studied under the bombardment of pulse powerful electron beam (electron energy-2300eV and electronic density-10A/cm2).
Secondary emission properties of impregnated barium scandate dispenser cathode has been studied under the bombardment of pulse powerful electron beam (electron energy-2300eV and electronic density-10A/cm2).
1989, 11(2): 191-198.
Abstract:
For a long time past, photocathodes have been used in radiation detectors and image tubes for the detection of low light level. Almost all photocathodes for above purposes have been designed to be low-current-density status (1A/lm) and rapidly fatigued by high illumination. In 70s, photocathodes, emerged as a means of generating high-current-demsity photoemission under the continuous or pulsed laser beam illuminations. This paper emphatically reports the advances in high-current-density photocathodes in this period and describes its applications. Finally, the evaluations and comparison are given.
For a long time past, photocathodes have been used in radiation detectors and image tubes for the detection of low light level. Almost all photocathodes for above purposes have been designed to be low-current-density status (1A/lm) and rapidly fatigued by high illumination. In 70s, photocathodes, emerged as a means of generating high-current-demsity photoemission under the continuous or pulsed laser beam illuminations. This paper emphatically reports the advances in high-current-density photocathodes in this period and describes its applications. Finally, the evaluations and comparison are given.
