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1989 Vol. 11, No. 3
Display Method:
1989, 11(3): 225-235.
Abstract:
Formulae of the third order geometric aberrations caused by the pirallcl planar deflection systems consisting of two planar deflectors disposed sequentially and orthogonally have been derived. These formulae can be used as an analytic solution for quickly estimating the geometric aberrations of a known deflection system and checking the related computer program. In view of attaining minimum and equal deflection aberration on the horizontal and vertical sides of a square scanning area, a method of optimum design is proposed. When the total length of the deflection region and the distance between the two deflectors are given, the optimum length of each of the two deflectors can be calculated by this method.
Formulae of the third order geometric aberrations caused by the pirallcl planar deflection systems consisting of two planar deflectors disposed sequentially and orthogonally have been derived. These formulae can be used as an analytic solution for quickly estimating the geometric aberrations of a known deflection system and checking the related computer program. In view of attaining minimum and equal deflection aberration on the horizontal and vertical sides of a square scanning area, a method of optimum design is proposed. When the total length of the deflection region and the distance between the two deflectors are given, the optimum length of each of the two deflectors can be calculated by this method.
1989, 11(3): 236-243.
Abstract:
An inverse design of electrostatic focusing field for electrostatic and magnetic imaging is investigated. Using the potential superimposition theorem of electrosta:ic field in multi-electrode system, a mathematical model has been developed and an optimization method has been introduced into computation for designing the electrostatic focusing field of the imaging system.
An inverse design of electrostatic focusing field for electrostatic and magnetic imaging is investigated. Using the potential superimposition theorem of electrosta:ic field in multi-electrode system, a mathematical model has been developed and an optimization method has been introduced into computation for designing the electrostatic focusing field of the imaging system.
1989, 11(3): 244-249.
Abstract:
that for practial emitters the measured values of the constant in Richardson's equation are always less than 120 A/cm2T is due to the nonuniformity of work function not to the reflection of electron at the surface potential barrier. For monocrystal faces, the measured and theoretical values agree. In fact, emission comes from those surface electrons already penetrated into the potential barrier before excitation. These furface electrons can neither move freely through vacuum non through conduction band of the metal, otherwise different crystal faces would not have different work functions. The adsorption of foreign atoms increases the energy and number of the surface electron and then lowers the work function.
that for practial emitters the measured values of the constant in Richardson's equation are always less than 120 A/cm2T is due to the nonuniformity of work function not to the reflection of electron at the surface potential barrier. For monocrystal faces, the measured and theoretical values agree. In fact, emission comes from those surface electrons already penetrated into the potential barrier before excitation. These furface electrons can neither move freely through vacuum non through conduction band of the metal, otherwise different crystal faces would not have different work functions. The adsorption of foreign atoms increases the energy and number of the surface electron and then lowers the work function.
1989, 11(3): 250-257.
Abstract:
An efficient measure is taken in simplification of Nakano s kernel of integral equations of arbitarily bent wires. By means of the moment method, great efforts are made in analysis and computation of the circularly polarized patterns, gain, axial ratio, front to back ratio and beamshaping of the resonant quadrifilar helical antennas as well as the feeding techniques and effect of a conducting plate on the antennas.
An efficient measure is taken in simplification of Nakano s kernel of integral equations of arbitarily bent wires. By means of the moment method, great efforts are made in analysis and computation of the circularly polarized patterns, gain, axial ratio, front to back ratio and beamshaping of the resonant quadrifilar helical antennas as well as the feeding techniques and effect of a conducting plate on the antennas.
1989, 11(3): 258-266.
Abstract:
Taking the sonar case for an example the application of a chirp signal for a linear array is described. In addition to the digitalized phase-correction technique, the array beamforming in the presence of noise is discussed. The theoretical analysis and computer simulation have shown that the system is characterized by the good range resolution and good angular resolution, as well as the high gain in signal-to-noise ratio.
Taking the sonar case for an example the application of a chirp signal for a linear array is described. In addition to the digitalized phase-correction technique, the array beamforming in the presence of noise is discussed. The theoretical analysis and computer simulation have shown that the system is characterized by the good range resolution and good angular resolution, as well as the high gain in signal-to-noise ratio.
1989, 11(3): 267-274.
Abstract:
The concepts of complete hypertree and primary subhypergraph are introduced, and a new method--primary subhypergaph mathod is presented for generating symbolic network functions. It is an improvement of primary subgraph method. Its resulting expressions are very compact, and its computinp time complexity is O(venl). In general, the total number of leaves nl is far less than the numberof primary subgraphs np, hence its computation -efficiency is higher than that of primary subgraph method.
The concepts of complete hypertree and primary subhypergraph are introduced, and a new method--primary subhypergaph mathod is presented for generating symbolic network functions. It is an improvement of primary subgraph method. Its resulting expressions are very compact, and its computinp time complexity is O(venl). In general, the total number of leaves nl is far less than the numberof primary subgraphs np, hence its computation -efficiency is higher than that of primary subgraph method.
1989, 11(3): 275-283.
Abstract:
The pressure-magnetoelectric effect of JFET is discussed by using standard relaxation techniques. A theoretical evaluation of the pressure sensitivity and Hall sensitivity of the n-channel silicon JFET with various geometries (W/L), gate voltages (VGS) and drain voltages (VDS) is made. The results show that when P0,B0, the current-pressure sensitivity is about 2.5%cm2/N, supposing W/L = 1/2-1. A junction field effect-pressure sensor with high stability and low noise is designed.
The pressure-magnetoelectric effect of JFET is discussed by using standard relaxation techniques. A theoretical evaluation of the pressure sensitivity and Hall sensitivity of the n-channel silicon JFET with various geometries (W/L), gate voltages (VGS) and drain voltages (VDS) is made. The results show that when P0,B0, the current-pressure sensitivity is about 2.5%cm2/N, supposing W/L = 1/2-1. A junction field effect-pressure sensor with high stability and low noise is designed.
1989, 11(3): 284-289.
Abstract:
The relationship between the majority carrier pulse width tp and DLTS intensity of gold acceptor EA in Si n+-p junction is studied. It is found that the DLTS intensity decreases monotonously with the increasing pulse width when tp1s. Some typical experimental results are given. The EA has two response regions: the majority carrier response region and minority carrier one. Just the two response regions caused the anomalous phenomena.
The relationship between the majority carrier pulse width tp and DLTS intensity of gold acceptor EA in Si n+-p junction is studied. It is found that the DLTS intensity decreases monotonously with the increasing pulse width when tp1s. Some typical experimental results are given. The EA has two response regions: the majority carrier response region and minority carrier one. Just the two response regions caused the anomalous phenomena.
1989, 11(3): 299-302.
Abstract:
The eigenvalue equation of TE modes of the slab optical waveguide with nonlinear substrate is derived, in which the optical power carried in the substrate is taken as a parameter. A simple graphic method is used for solving this problem.
The eigenvalue equation of TE modes of the slab optical waveguide with nonlinear substrate is derived, in which the optical power carried in the substrate is taken as a parameter. A simple graphic method is used for solving this problem.
1989, 11(3): 303-307.
Abstract:
The higher order mode cut-off characteristics of finned rectangular waveguides are discussed. Data are given by using the TLM method on the normalized cut-off wavelength of the first seven higher order modes. Also, the way to minimize the errors of the TLM method is indicated.
The higher order mode cut-off characteristics of finned rectangular waveguides are discussed. Data are given by using the TLM method on the normalized cut-off wavelength of the first seven higher order modes. Also, the way to minimize the errors of the TLM method is indicated.
1989, 11(3): 308-313.
Abstract:
The transformation relations of normal rectangular, cylindrical and spherical vector wave functions are derived. With these relations, it will be convenient for engineering.
The transformation relations of normal rectangular, cylindrical and spherical vector wave functions are derived. With these relations, it will be convenient for engineering.
1989, 11(3): 314-319.
Abstract:
The coupling properties of a transverse slot in the common wall between butting two rectangular waveguides are discussed. By means of Galerkin s method which takes into account the wall thickness, equivalent magnetic currents on the aperture surface of the slot are obtained, and then general formulas of scattering fields and of .equivalent parameters arc derived. The dimensions as well as seats of those two waveguides and the slot, and the thickness of the wall are arbitrary. For example, the transforming coefficients and the VSWRs of numerical calculation and experiments are given. The theoretical and experimental results are in good agreement.
The coupling properties of a transverse slot in the common wall between butting two rectangular waveguides are discussed. By means of Galerkin s method which takes into account the wall thickness, equivalent magnetic currents on the aperture surface of the slot are obtained, and then general formulas of scattering fields and of .equivalent parameters arc derived. The dimensions as well as seats of those two waveguides and the slot, and the thickness of the wall are arbitrary. For example, the transforming coefficients and the VSWRs of numerical calculation and experiments are given. The theoretical and experimental results are in good agreement.
1989, 11(3): 320-323.
Abstract:
The characteristic impedance of unscreened slab-line is obtained, based on the investigation of the properties of the equipotential line in vertical stripline. Physical concepts of the developed method is clear. The computed results agree well with those in the literatures.
The characteristic impedance of unscreened slab-line is obtained, based on the investigation of the properties of the equipotential line in vertical stripline. Physical concepts of the developed method is clear. The computed results agree well with those in the literatures.
1989, 11(3): 324-327.
Abstract:
A design method of H shape impedance transformer is described briefly, and how to determine the cutoff wavelength is discussed, in order to decrease the difference of power output within the operational bandwith of magnetron. At last some tubes are mounred and tested. The results are satisfactory.
A design method of H shape impedance transformer is described briefly, and how to determine the cutoff wavelength is discussed, in order to decrease the difference of power output within the operational bandwith of magnetron. At last some tubes are mounred and tested. The results are satisfactory.
1989, 11(3): 328-332.
Abstract:
A hysteresis inductor via a hysteresis resistor is realized. Then the behaviors of bifurcation and chaos in a second-order non-autonomous dynamic circuit containing the hysteresis inductor are studied. The results of computer simulation agree well with the experiments in qualitative behaviour. The bifurcation results obtained are valuable.
A hysteresis inductor via a hysteresis resistor is realized. Then the behaviors of bifurcation and chaos in a second-order non-autonomous dynamic circuit containing the hysteresis inductor are studied. The results of computer simulation agree well with the experiments in qualitative behaviour. The bifurcation results obtained are valuable.
1989, 11(3): 333-336.
Abstract:
Deep levels in Ga1-xAlxAs/GaAs double-heterojunction LEDs have been studied by DLTS. The Ga1-xAlxAs DH material was grown by LPE technique. The dark deitcts are ob-jerved with an infrared line scanner. The effect of the oxygen contamination on the deep levels in Si-doped active layer is found. The activation energy EC-ED0.29 eV. The DSD are sometimes generated in the emitting area. It did not related to the deep levels obviously.
Deep levels in Ga1-xAlxAs/GaAs double-heterojunction LEDs have been studied by DLTS. The Ga1-xAlxAs DH material was grown by LPE technique. The dark deitcts are ob-jerved with an infrared line scanner. The effect of the oxygen contamination on the deep levels in Si-doped active layer is found. The activation energy EC-ED0.29 eV. The DSD are sometimes generated in the emitting area. It did not related to the deep levels obviously.
1989, 11(3): 290-298.
Abstract:
Recent developments in microstrip antenna theory and technology are surveyed. Emphasis is on those in the basic theories and techniques for circularly polarized, broadband, multiband operations and feeding methods, as well as several recently developed micro-strip arrays such as mm-wave microstrip arrays and active monolithic phased arrays. Finally, directions for microstrip antenna developments and applications are summarized.
Recent developments in microstrip antenna theory and technology are surveyed. Emphasis is on those in the basic theories and techniques for circularly polarized, broadband, multiband operations and feeding methods, as well as several recently developed micro-strip arrays such as mm-wave microstrip arrays and active monolithic phased arrays. Finally, directions for microstrip antenna developments and applications are summarized.
