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1991 Vol. 13, No. 2
Display Method:
1991, 13(2): 113-118.
Abstract:
The design of ternary cdge-triggered JKL-type filp-flop is proposed. The computer simulation and the test in experimental circuit made up with TTL gate show this flip-flop has the expected logic functioas.
The design of ternary cdge-triggered JKL-type filp-flop is proposed. The computer simulation and the test in experimental circuit made up with TTL gate show this flip-flop has the expected logic functioas.
1991, 13(2): 119-124.
Abstract:
The electromagnetic field problem of a rectangular grating illuminated with TM wave is studied theoretically by means of rigorous field-matching and moment method. The numerical calculations show that the grating, as a frequency scan antenna, can produce perfect blazing in a wide range of incident angle only through adjusting the size of width and depth of the groove no matter Bragg condition is satisfied or not. Higher efficiency and broader frequency band of - 1 order diffraction wave can be achieved only at the larger reciprocal incident angle. And very broad frequency band can be expected when the grating is employed as a reflecting mirror in an orotron. The effective grating position and phase change of reflection wave by grating are also numerically presented.
The electromagnetic field problem of a rectangular grating illuminated with TM wave is studied theoretically by means of rigorous field-matching and moment method. The numerical calculations show that the grating, as a frequency scan antenna, can produce perfect blazing in a wide range of incident angle only through adjusting the size of width and depth of the groove no matter Bragg condition is satisfied or not. Higher efficiency and broader frequency band of - 1 order diffraction wave can be achieved only at the larger reciprocal incident angle. And very broad frequency band can be expected when the grating is employed as a reflecting mirror in an orotron. The effective grating position and phase change of reflection wave by grating are also numerically presented.
1991, 13(2): 125-130.
Abstract:
Usually, weighted array antennas are designed by using the statistical appro-ach. In this paper, the application of the Markoy chains of a random process to the design of density weighted or phase weighted arrays is considered. The new approach is proposed to improve the Statistical approach and devides the array into several parts, in which the selection of the element location or phase is performed correlatively utilizing the probability density function for specifying the location or phase of elements at every part.
Usually, weighted array antennas are designed by using the statistical appro-ach. In this paper, the application of the Markoy chains of a random process to the design of density weighted or phase weighted arrays is considered. The new approach is proposed to improve the Statistical approach and devides the array into several parts, in which the selection of the element location or phase is performed correlatively utilizing the probability density function for specifying the location or phase of elements at every part.
1991, 13(2): 131-137.
Abstract:
A definition of combined phase centre for conical horn feeds is given. Formulas of E-plane and H-plane combined phase centre for conical horns and the corres-ponding optimal model are presented, and a fast optimization method for solving this model is given. By using this method, the phase centre corrugated horn with reference to operating frequencies and distances is discussed.
A definition of combined phase centre for conical horn feeds is given. Formulas of E-plane and H-plane combined phase centre for conical horns and the corres-ponding optimal model are presented, and a fast optimization method for solving this model is given. By using this method, the phase centre corrugated horn with reference to operating frequencies and distances is discussed.
1991, 13(2): 138-144.
Abstract:
An analysis of solving the electromagnetic scattering by buried objects using the vector vvave function expansion is presented. For expanding the boundary conditions both on the planar air-earth interface and on he spherical surface, the conversion relations be-tween the cylindrical and spherical vector wave functions are derived. Hence the vector wave function expansion is conveniently applied to solve this complex boundary value problem. For the excitation of the incident plane wave and the dipole above the earth, the scattering patterns of the buried conducting and dielectric spheres are presented and discussed.
An analysis of solving the electromagnetic scattering by buried objects using the vector vvave function expansion is presented. For expanding the boundary conditions both on the planar air-earth interface and on he spherical surface, the conversion relations be-tween the cylindrical and spherical vector wave functions are derived. Hence the vector wave function expansion is conveniently applied to solve this complex boundary value problem. For the excitation of the incident plane wave and the dipole above the earth, the scattering patterns of the buried conducting and dielectric spheres are presented and discussed.
1991, 13(2): 145-150.
Abstract:
The regularity of electron motion with non-circular orbits in an electro-static centrifugal system is investigated. Through extensive numerical computation, analysis and investigation, the following results are obtained: there exist radial and azimuthal perio-dicities in the non-circular orbit motion of electrons in the system and these periodicities are related to the transverse injection velocity and position of the eletrons and the electrostatic voltage applied in the system but have little relation to the transverse injection angle of the electrons; the ratios between the radial and the azimuthal periods of the electron motion under different parameters approach to the same constant; if the injecting transverse electron velocity is less than 0.35c, the radial period of the electron motion is inversely proportional to the square root of the electrostatic voltage applied in the system; and the radial periods of electron motion in the system are equal to those of the corresponding characteristic oscillation of the electrons in the electrostatic centrifugal system.
The regularity of electron motion with non-circular orbits in an electro-static centrifugal system is investigated. Through extensive numerical computation, analysis and investigation, the following results are obtained: there exist radial and azimuthal perio-dicities in the non-circular orbit motion of electrons in the system and these periodicities are related to the transverse injection velocity and position of the eletrons and the electrostatic voltage applied in the system but have little relation to the transverse injection angle of the electrons; the ratios between the radial and the azimuthal periods of the electron motion under different parameters approach to the same constant; if the injecting transverse electron velocity is less than 0.35c, the radial period of the electron motion is inversely proportional to the square root of the electrostatic voltage applied in the system; and the radial periods of electron motion in the system are equal to those of the corresponding characteristic oscillation of the electrons in the electrostatic centrifugal system.
1991, 13(2): 151-158.
Abstract:
A thin post with arbitrary height in a rectangular waveguide is treated by the moment method. The electric field integral equation of the post is solved with the pulse expansion and point matching. The convergence of some series involved is accelerated oy using some mathematical treatments. The current distribution on the post is discussed. A new and more exact closed form for it is given The computed results show in good agreement with those in Marcuvitz s Waveguide Handbook.
A thin post with arbitrary height in a rectangular waveguide is treated by the moment method. The electric field integral equation of the post is solved with the pulse expansion and point matching. The convergence of some series involved is accelerated oy using some mathematical treatments. The current distribution on the post is discussed. A new and more exact closed form for it is given The computed results show in good agreement with those in Marcuvitz s Waveguide Handbook.
1991, 13(2): 159-168.
Abstract:
By solving the basie equations of magnetic field in the anisotropic magnetic media in which the tensor ik is symmetric, an integral formula for anisotropic vector potential A is obtained. By which the character form ulae for self- and mutual inductances are deri-ved in scalar and tensor forms, and their transformation formulae are also deduced. Finally the formulae are checked by praclical examples.
By solving the basie equations of magnetic field in the anisotropic magnetic media in which the tensor ik is symmetric, an integral formula for anisotropic vector potential A is obtained. By which the character form ulae for self- and mutual inductances are deri-ved in scalar and tensor forms, and their transformation formulae are also deduced. Finally the formulae are checked by praclical examples.
1991, 13(2): 169-176.
Abstract:
The effect of the -Si:H target voltage on the spectral photosensitivity is measured in a demountable apparatus with interchangeable targets. It is found that the effect of target voltage on the photoresponse increases when the light wavelength decreases. The target photocurrent is and saturation voltage Vs are analysed. It is shown that Vs[(pp)-1, w2]. pp is calculated from measured Vs, value. It is found that pp value decreases when the light wavelength decreases. The optimal thicknesses of -Si:H targets for homogeneous light and achromatic light are estimated.
The effect of the -Si:H target voltage on the spectral photosensitivity is measured in a demountable apparatus with interchangeable targets. It is found that the effect of target voltage on the photoresponse increases when the light wavelength decreases. The target photocurrent is and saturation voltage Vs are analysed. It is shown that Vs[(pp)-1, w2]. pp is calculated from measured Vs, value. It is found that pp value decreases when the light wavelength decreases. The optimal thicknesses of -Si:H targets for homogeneous light and achromatic light are estimated.
1991, 13(2): 177-182.
Abstract:
The activation experiments have been conducted with bulk p+ GaAs single crystal samples without any additional epitaxy or cleavage in vacuum. AES analysis is used to assist the establishment of surface cleaning processing. The easy determination of fusion point of pure Al nearby the sample helped us out the surface temperature control problem. The samples treated at relatively low background vacuum (2-610-7Pa) have a white light photoemission as high as 1000A/lm.
The activation experiments have been conducted with bulk p+ GaAs single crystal samples without any additional epitaxy or cleavage in vacuum. AES analysis is used to assist the establishment of surface cleaning processing. The easy determination of fusion point of pure Al nearby the sample helped us out the surface temperature control problem. The samples treated at relatively low background vacuum (2-610-7Pa) have a white light photoemission as high as 1000A/lm.
1991, 13(2): 183-192.
Abstract:
Based on the synthetic study of the previous magnetic combined objective lenses, such as MOL (moving objective lens), VAL (variable axis lens), SOL (swinging objective lens) etc; the general theory of combined objective lenses is approached, and a set of general formulas is presented. A new combined objective lens called Bent Objective Len (BOL) is proposed for improving the optical properties in electron beam systems. Using the analytical functions of the magnetic lens field and electron ray, the aberration analysis of the BOL system is performed, and a practical BOL system is also designed. The numerically computational results indicate that this system offers extremely small coma and transverse chromatic aberrations. At the corner of a 5 X 5mm2 deflection field with a 5 mrad aperture angle and 0.0001 beam voltage ripple, the beam blur caused by coma is 0.00.5 m nad the transverse chromatic aberration is 0.001 m.
Based on the synthetic study of the previous magnetic combined objective lenses, such as MOL (moving objective lens), VAL (variable axis lens), SOL (swinging objective lens) etc; the general theory of combined objective lenses is approached, and a set of general formulas is presented. A new combined objective lens called Bent Objective Len (BOL) is proposed for improving the optical properties in electron beam systems. Using the analytical functions of the magnetic lens field and electron ray, the aberration analysis of the BOL system is performed, and a practical BOL system is also designed. The numerically computational results indicate that this system offers extremely small coma and transverse chromatic aberrations. At the corner of a 5 X 5mm2 deflection field with a 5 mrad aperture angle and 0.0001 beam voltage ripple, the beam blur caused by coma is 0.00.5 m nad the transverse chromatic aberration is 0.001 m.
1991, 13(2): 193-196.
Abstract:
Under the physical optics approximation, Bojarski s Identity is expanded to the general bistatic scattering scheme. The result is more general than that obta-ined under the prerequisite k Ei =k0Ei = 0 by S. R. Raz (1976). The benefit of the bistatic depolarized scattering imaging is demonstrated, and the improper tre-atment in the derivation deduced by S. R. Raz is pointed out.
Under the physical optics approximation, Bojarski s Identity is expanded to the general bistatic scattering scheme. The result is more general than that obta-ined under the prerequisite k Ei =k0Ei = 0 by S. R. Raz (1976). The benefit of the bistatic depolarized scattering imaging is demonstrated, and the improper tre-atment in the derivation deduced by S. R. Raz is pointed out.
1991, 13(2): 197-201.
Abstract:
The complex parameters of single or double imhomogeneous lossy dielectric slabs can be determined if the slabs is illuminated by a harmonic electromagnetic wave and the scatte-red field is measured. The method of determiniing parameters is described and the numerical re-sults are given.
The complex parameters of single or double imhomogeneous lossy dielectric slabs can be determined if the slabs is illuminated by a harmonic electromagnetic wave and the scatte-red field is measured. The method of determiniing parameters is described and the numerical re-sults are given.
1991, 13(2): 202-206.
Abstract:
By utilizing transmission line theory, practical expressions for the longitudinal nonuniformity of the electric field distribution in TEM cells are obtained. Numerical results agree well with experimental ones shown by M. L. Crawford (1977) at some frequencies. The results presented can be applied in correcting errors caused by probe location deviation in the logitudinal direction so as to reach higher accuracies in EMC measurements and probe calibration with TEM cells.
By utilizing transmission line theory, practical expressions for the longitudinal nonuniformity of the electric field distribution in TEM cells are obtained. Numerical results agree well with experimental ones shown by M. L. Crawford (1977) at some frequencies. The results presented can be applied in correcting errors caused by probe location deviation in the logitudinal direction so as to reach higher accuracies in EMC measurements and probe calibration with TEM cells.
1991, 13(2): 207-210.
Abstract:
The reciprocity and the unitarity of non-loss linear networks in zero state are derived from the mucual energy theorem.
The reciprocity and the unitarity of non-loss linear networks in zero state are derived from the mucual energy theorem.
1991, 13(2): 211-216.
Abstract:
A new lower bound on the dimensions of Goppa codes bas been given by Feng Guiliang (1983). In this paper, at first, a formula for computing the lower bound in some cases is offered, and a upper bound on the dimensions of Goppa codes and a method of finding the upper bound are given. In some special cases, the dimensions of Goppa codes can be obtained by using the upper bound and the lower bound.
A new lower bound on the dimensions of Goppa codes bas been given by Feng Guiliang (1983). In this paper, at first, a formula for computing the lower bound in some cases is offered, and a upper bound on the dimensions of Goppa codes and a method of finding the upper bound are given. In some special cases, the dimensions of Goppa codes can be obtained by using the upper bound and the lower bound.
1991, 13(2): 217-220.
Abstract:
DC discharge characteristic for metai vapor laser at high power level were mea-sured for the first time using He, Ne, N2, Ar as buffer gases. It was found that He is the best buffer gas for DC discharge preheating. More than 5kW electric power was injected into plasma tube at 20 mm Hg He pressure and 1A ctive anodic oxidation, by which the ununiform. tube reached to 1400℃ in less than an hour.
DC discharge characteristic for metai vapor laser at high power level were mea-sured for the first time using He, Ne, N2, Ar as buffer gases. It was found that He is the best buffer gas for DC discharge preheating. More than 5kW electric power was injected into plasma tube at 20 mm Hg He pressure and 1A ctive anodic oxidation, by which the ununiform. tube reached to 1400℃ in less than an hour.
1991, 13(2): 221-224.
Abstract:
A new technique called selective anodic oxidation, by which the ununiform epilayers can be thinned, is presented. The thickness of n+-layers of GaAs IMPATT diodes with n+-n-n++ structure has been strictly controlled by the use of this technique. This results in the efficiency of IMPATT diodes up to its theoretical value.
A new technique called selective anodic oxidation, by which the ununiform epilayers can be thinned, is presented. The thickness of n+-layers of GaAs IMPATT diodes with n+-n-n++ structure has been strictly controlled by the use of this technique. This results in the efficiency of IMPATT diodes up to its theoretical value.
