Email alert
1981 Vol. 3, No. 3
Display Method:
1981, 3(3): 137-142.
Abstract:
In this paper the element pattern-steerable adaptive circular arrays are described. The element consists of three-orthogonal dipoles. All the element radiation patterns in the array can be steered by a set of weightings to point to an arbitrary specified direction. Thus a high directional beam in an arbitrary directional position within a 3-dimensional space can be formed to capture a desired signal effectively. On the above basis the techniques of the adaptive linear array of uniformly spaced isotropic element investigated by W.F.Gabriel are generalized to the special topic of the element patternsteerable adaptive circular arrays by means of the concept of equivalent interference source. This paper discusses following theoretical aspects of the said arrays: the array farzone radiation field, the direction-controlled weighting factors of the element radiation pattern, the covariance matrix of the set of system inputs, the orthogonal resolution of the array output pattern, the transient characteristic for total output noise power of the array system.
In this paper the element pattern-steerable adaptive circular arrays are described. The element consists of three-orthogonal dipoles. All the element radiation patterns in the array can be steered by a set of weightings to point to an arbitrary specified direction. Thus a high directional beam in an arbitrary directional position within a 3-dimensional space can be formed to capture a desired signal effectively. On the above basis the techniques of the adaptive linear array of uniformly spaced isotropic element investigated by W.F.Gabriel are generalized to the special topic of the element patternsteerable adaptive circular arrays by means of the concept of equivalent interference source. This paper discusses following theoretical aspects of the said arrays: the array farzone radiation field, the direction-controlled weighting factors of the element radiation pattern, the covariance matrix of the set of system inputs, the orthogonal resolution of the array output pattern, the transient characteristic for total output noise power of the array system.
1981, 3(3): 143-151.
Abstract:
This report covers the studies of the characteristics of the scattering patterns from a subreflector of the modified monopulse dual reflector antennas. In this report, at first the basic computed formulas of the far-field sum and difference scatering patterns are deduced, and then the computed and measured results of the scattering patterns for the antenna of about 60 A diameters are obtained.By the analysis and experiment of the scattering characteristics of a subreflector of the monopulse antenna, a high sum efficiency and slope of secondary difference pattern can be obtained, using optically shaped reflector approach. Finally, the measured results of the modified cassegrainian monopulse antenna are given.
This report covers the studies of the characteristics of the scattering patterns from a subreflector of the modified monopulse dual reflector antennas. In this report, at first the basic computed formulas of the far-field sum and difference scatering patterns are deduced, and then the computed and measured results of the scattering patterns for the antenna of about 60 A diameters are obtained.By the analysis and experiment of the scattering characteristics of a subreflector of the monopulse antenna, a high sum efficiency and slope of secondary difference pattern can be obtained, using optically shaped reflector approach. Finally, the measured results of the modified cassegrainian monopulse antenna are given.
1981, 3(3): 152-159.
Abstract:
A review is made of recent progress in the study of oxide cathodes using surface techniques. Beginning with the careful and rather detailed studies of the thermionic properties of BaO, (thus leading to the Ir-BaO cathode initiated by the NRL group) we pass over to report surface studies of the triple carbonate cathode thereby touching on the socalled Medicus cathode.
A review is made of recent progress in the study of oxide cathodes using surface techniques. Beginning with the careful and rather detailed studies of the thermionic properties of BaO, (thus leading to the Ir-BaO cathode initiated by the NRL group) we pass over to report surface studies of the triple carbonate cathode thereby touching on the socalled Medicus cathode.
1981, 3(3): 160-166.
Abstract:
In an O type high power travelling wave tube (TWT), its power capacity is determined by the heat conduction characteristic of the slow wave structure (SWS). When the open type SWS is supported by dielectric rods of trapezoid shape in cross section, the one dimensional equation of the temperature difference between the hot spot of the SWS and the barrel of the tube is derived in this article. The value of temperature difference determines the power capacity of the TWT. The equations obtained are then applied to analyze different kinds of practical open type SWS. Theoretical calculation is in good agreement with measurement. Some values. of temperature difference for several practical SWS, some of which are made by spring pressed, and some by brazing, are given for comparision and for use in technological design and analysis.
In an O type high power travelling wave tube (TWT), its power capacity is determined by the heat conduction characteristic of the slow wave structure (SWS). When the open type SWS is supported by dielectric rods of trapezoid shape in cross section, the one dimensional equation of the temperature difference between the hot spot of the SWS and the barrel of the tube is derived in this article. The value of temperature difference determines the power capacity of the TWT. The equations obtained are then applied to analyze different kinds of practical open type SWS. Theoretical calculation is in good agreement with measurement. Some values. of temperature difference for several practical SWS, some of which are made by spring pressed, and some by brazing, are given for comparision and for use in technological design and analysis.
1981, 3(3): 167-172.
Abstract:
This paper explains the image expansion and confusion of the red and blue primary colours caused by the electric charge accumulation on the oil film in the colour TV light valve tube.
This paper explains the image expansion and confusion of the red and blue primary colours caused by the electric charge accumulation on the oil film in the colour TV light valve tube.
1981, 3(3): 173-184.
Abstract:
In this paper the self-sharpening effect of electron beam landing on the target in a vidicon and its influence on resolution of electron beam have been digitally analyzed with computer. The mathematical-physical models applied are as follows: The distribution of current density in electron beam is Gaussian; the energy distribution of electrons in beam is Maxwellian; and the signal-readout model is capacitor discharge model. When the model of cross section of beam is one-dimensional, the self-sharpening effect of beam in 1¼ and 2/3plumbicon, 1 Sb2S3 vidicon and 1staticon are computed. Also their influences on AR (amplitude response) of electron beam have been computed. The influences of beam current, signal current, equivalent temperature of beam, target capacitor and velocity of scanning on the self-sharpening effect have been analyzed. when the model of cross section of beam is two-dimensional, the self-sharpening effect of beam in1¼plumbicon, as an example, is given.
In this paper the self-sharpening effect of electron beam landing on the target in a vidicon and its influence on resolution of electron beam have been digitally analyzed with computer. The mathematical-physical models applied are as follows: The distribution of current density in electron beam is Gaussian; the energy distribution of electrons in beam is Maxwellian; and the signal-readout model is capacitor discharge model. When the model of cross section of beam is one-dimensional, the self-sharpening effect of beam in 1¼ and 2/3plumbicon, 1 Sb2S3 vidicon and 1staticon are computed. Also their influences on AR (amplitude response) of electron beam have been computed. The influences of beam current, signal current, equivalent temperature of beam, target capacitor and velocity of scanning on the self-sharpening effect have been analyzed. when the model of cross section of beam is two-dimensional, the self-sharpening effect of beam in1¼plumbicon, as an example, is given.
1981, 3(3): 185-190.
Abstract:
The long pulse electron beam system reported here was constructed for transverse pumping and e-beam sustained discharge large energy gas laser. The electron beam parameters are: the beam energy about 200-250 keV, pulse duration (PWHM) about 1-3s, current density in 0.5-8 A/cm2 range and beam area 10010cm2. With this system, we have performed XeCl laser experiments and obtained laser energy output-1J in 1.9 1 active volume. Recently this system was used as a pumping source for CO2 laser, and we have preliminarily obtained 360 J laser energy in 7,85 1 active volume.
The long pulse electron beam system reported here was constructed for transverse pumping and e-beam sustained discharge large energy gas laser. The electron beam parameters are: the beam energy about 200-250 keV, pulse duration (PWHM) about 1-3s, current density in 0.5-8 A/cm2 range and beam area 10010cm2. With this system, we have performed XeCl laser experiments and obtained laser energy output-1J in 1.9 1 active volume. Recently this system was used as a pumping source for CO2 laser, and we have preliminarily obtained 360 J laser energy in 7,85 1 active volume.
1981, 3(3): 191-192.
Abstract:
A dispenser cathode which consists of a porous body of tungsten impregnated with barium scandate has been developed. It has good properties: high emission current density, low evaporation rate, good reactivation ability after poisoning and long life. This kind of cathode is suitable for use as an electron emitter for certain high power microwave tubes and the like.
A dispenser cathode which consists of a porous body of tungsten impregnated with barium scandate has been developed. It has good properties: high emission current density, low evaporation rate, good reactivation ability after poisoning and long life. This kind of cathode is suitable for use as an electron emitter for certain high power microwave tubes and the like.
1981, 3(3): 193-195.
Abstract:
In this paper the effects of dielectric sheet on the array antenna are described on the concept of element cell. The formulae suitable for the computer calculation are derived by the use of transmission line circuit theory. Useful results are obtained by the use of computer type-719, and the correctness of the results is discussed. The theoretical data are in agreement with experimental results obtained from the waveguide simulators.
In this paper the effects of dielectric sheet on the array antenna are described on the concept of element cell. The formulae suitable for the computer calculation are derived by the use of transmission line circuit theory. Useful results are obtained by the use of computer type-719, and the correctness of the results is discussed. The theoretical data are in agreement with experimental results obtained from the waveguide simulators.
1981, 3(3): 196-200.
Abstract:
An improved algorithm for FFT is proposed. The Fourier transforms of a complex discrete sequence with N = 2r points are performed by the operation of (-3) N/2 times of multiplication. The speed of the algorithm is faster than the conventional FFT. The speed up ratio is about 3/(-3).
An improved algorithm for FFT is proposed. The Fourier transforms of a complex discrete sequence with N = 2r points are performed by the operation of (-3) N/2 times of multiplication. The speed of the algorithm is faster than the conventional FFT. The speed up ratio is about 3/(-3).
