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1988 Vol. 10, No. 2
Display Method:
1988, 10(2): 97-105.
Abstract:
Martens (1984) proposed a high efficient and simple formed DFT algorithm-RCFA,, whose efficiency can be compared with that of WFTA or that of PFA, and whose structure is similar to that of FFT. The authors have proved that, in the case of radix 2, the RCFA is exactly equivalent to the twiddle factor merged frequency-decial FFT algorithm. The twiddle factor merged time-decimal FFT algoorithm is provided in this paper. Thus, in anycase, the FFT algorithm used currently can be replaced by the more efficient algorithm--the twiddle factor merged FFT algorithm, with exactly the same external property and the similar internal structure. In addition, the software for implementing the twiddle factor merge FFT algorithm (TMFFT) is also provided.
Martens (1984) proposed a high efficient and simple formed DFT algorithm-RCFA,, whose efficiency can be compared with that of WFTA or that of PFA, and whose structure is similar to that of FFT. The authors have proved that, in the case of radix 2, the RCFA is exactly equivalent to the twiddle factor merged frequency-decial FFT algorithm. The twiddle factor merged time-decimal FFT algoorithm is provided in this paper. Thus, in anycase, the FFT algorithm used currently can be replaced by the more efficient algorithm--the twiddle factor merged FFT algorithm, with exactly the same external property and the similar internal structure. In addition, the software for implementing the twiddle factor merge FFT algorithm (TMFFT) is also provided.
1988, 10(2): 106-112.
Abstract:
This paper presents a new edge detector using 5x5 window, which can reduce the noise effect efficiently but not increase the width of the detected edge which always happened,, in case of using 5x5 window edge detector. Besides that, in order to handle the problem that the contrast reduced in the dark region is caused by underexposure, this detector uses a auto-changeable threshold, so that it can detect the edge in regions of different grey background correctly.
This paper presents a new edge detector using 5x5 window, which can reduce the noise effect efficiently but not increase the width of the detected edge which always happened,, in case of using 5x5 window edge detector. Besides that, in order to handle the problem that the contrast reduced in the dark region is caused by underexposure, this detector uses a auto-changeable threshold, so that it can detect the edge in regions of different grey background correctly.
1988, 10(2): 113-119.
Abstract:
Starting from the relativistic motion equation and the energy equation of the electron, a large-signal theory which describes the beam-wave interaction of the gyro-peniotron for arbitrary TEmn mode and arbitrary harmonic of the cyclotron frequency is presented. Numerical simulation shows that under defined conditions an electronic efficiency of about 45% for the third cyclotron harmonic at an operation frequency of 35 GHz could be obtained, while the required DC magnetic field is only 4.2 kGs. This fact indicates that this device could be efficiently operated at high efficiency and low magnetic field. Therefore, the practical application of the gyro-device will be greatly exended and the potential for sort-millimeter and sub-millimeter wavelength exists.
Starting from the relativistic motion equation and the energy equation of the electron, a large-signal theory which describes the beam-wave interaction of the gyro-peniotron for arbitrary TEmn mode and arbitrary harmonic of the cyclotron frequency is presented. Numerical simulation shows that under defined conditions an electronic efficiency of about 45% for the third cyclotron harmonic at an operation frequency of 35 GHz could be obtained, while the required DC magnetic field is only 4.2 kGs. This fact indicates that this device could be efficiently operated at high efficiency and low magnetic field. Therefore, the practical application of the gyro-device will be greatly exended and the potential for sort-millimeter and sub-millimeter wavelength exists.
1988, 10(2): 120-126.
Abstract:
A new approach to the EM scattering problem of an inhomogeneous lossy dielectric body is proposed. It is shown that the entire interier electric field distribution can be obtained from the measured exterier field distribution by simple recurrence relations. Detailed derivations of those recurrence relations for the field distribution inside the scattering body are presented, and the results obtained by computer simulations are given.
A new approach to the EM scattering problem of an inhomogeneous lossy dielectric body is proposed. It is shown that the entire interier electric field distribution can be obtained from the measured exterier field distribution by simple recurrence relations. Detailed derivations of those recurrence relations for the field distribution inside the scattering body are presented, and the results obtained by computer simulations are given.
1988, 10(2): 127-136.
Abstract:
The theory of electromagnetic missiles established by T. T. Wu (1985) is developed. The asymptotis condition for the spectrum of the exciting signal of the electromagnetic missile system is derived and several kinds of possible electromagnetic missile systems are given.
The theory of electromagnetic missiles established by T. T. Wu (1985) is developed. The asymptotis condition for the spectrum of the exciting signal of the electromagnetic missile system is derived and several kinds of possible electromagnetic missile systems are given.
1988, 10(2): 137-150.
Abstract:
A new method for switched-capacitor filleter (SCF) realization by using the linear transformation techique is described. It is shown that using VCVS equivalent transformation to revise the original LC ladder filter, sixteen basic sections are obtained. By using them, it is possible to realize all four kinds of filters-lowpass, highpass, bandpass and bandstop filter. As example, the paper presents their designs. A Nth order filter only requires N amplifiers and is insensitive to the parasitic capacitors. The experimental results of 3rd order lowpass and 6th order bandpass SCF are given and agree well with the theory.
A new method for switched-capacitor filleter (SCF) realization by using the linear transformation techique is described. It is shown that using VCVS equivalent transformation to revise the original LC ladder filter, sixteen basic sections are obtained. By using them, it is possible to realize all four kinds of filters-lowpass, highpass, bandpass and bandstop filter. As example, the paper presents their designs. A Nth order filter only requires N amplifiers and is insensitive to the parasitic capacitors. The experimental results of 3rd order lowpass and 6th order bandpass SCF are given and agree well with the theory.
1988, 10(2): 151-157.
Abstract:
A multi-octave microstrip balun double balanced mixer has been developed. This mixer which is consisted of a broad-band balun and a diode ring exhibits extremely encouraging performance. Within the multi-octave bandwidth from 1 to 18 GHz, the average DSB noise figure is 6 dB, and the maximum DSB noise figure is 8.7 dB, and both LO-RF and LO-IF isolations are more than 15 dB.
A multi-octave microstrip balun double balanced mixer has been developed. This mixer which is consisted of a broad-band balun and a diode ring exhibits extremely encouraging performance. Within the multi-octave bandwidth from 1 to 18 GHz, the average DSB noise figure is 6 dB, and the maximum DSB noise figure is 8.7 dB, and both LO-RF and LO-IF isolations are more than 15 dB.
1988, 10(2): 158-164.
Abstract:
Based on Firsov theory (1959), the concept of the Slater wave function etc. is introduced, then the equation of the effect of atomic structure on Z-oscillation of Se(E) is derived. And by using the molecular orbital theory, the equation of the effect of the molecular structure on Z oscillation of,Se(E) is obtained. These obtained equatio nare suitable for light or heavy element target not only in the lower energy range (10-1000 keV), but also at the higher energy.The results calculated with these equations for Z1C and Li+Z2 in the lower energy range, S+Na and F+Agin the higher energy range, and H+-CdTe all are in good agreement with the experimental ones given in the literatures.
Based on Firsov theory (1959), the concept of the Slater wave function etc. is introduced, then the equation of the effect of atomic structure on Z-oscillation of Se(E) is derived. And by using the molecular orbital theory, the equation of the effect of the molecular structure on Z oscillation of,Se(E) is obtained. These obtained equatio nare suitable for light or heavy element target not only in the lower energy range (10-1000 keV), but also at the higher energy.The results calculated with these equations for Z1C and Li+Z2 in the lower energy range, S+Na and F+Agin the higher energy range, and H+-CdTe all are in good agreement with the experimental ones given in the literatures.
1988, 10(2): 165-173.
Abstract:
A microcomputerized measuring system is developed. This system automatically acquires an I-V characteristic curve in 5 seconds with an accuracy of 0.05% (ful scale-range). The Schottky extrapolation field-free emission, the inflection point emission, the flection point emission, the average effective work, function, the Richardson .work function, the work function distribution at the operation temperature and other important informations that reflect properties of cathode are obtained by this system. The results after analysing four type of cathodes demonstrate that this system is very suitable for measuring the property changes of the cathode in the processes of activation, ageing, poisoning and life test. It is proved that this system can also be used to monitor the property of the eathode in the assembled tube by measuring a grid controlled travelling-wave tube.
A microcomputerized measuring system is developed. This system automatically acquires an I-V characteristic curve in 5 seconds with an accuracy of 0.05% (ful scale-range). The Schottky extrapolation field-free emission, the inflection point emission, the flection point emission, the average effective work, function, the Richardson .work function, the work function distribution at the operation temperature and other important informations that reflect properties of cathode are obtained by this system. The results after analysing four type of cathodes demonstrate that this system is very suitable for measuring the property changes of the cathode in the processes of activation, ageing, poisoning and life test. It is proved that this system can also be used to monitor the property of the eathode in the assembled tube by measuring a grid controlled travelling-wave tube.
1988, 10(2): 174-179.
Abstract:
Based on the Born approximation, an analytical theory for computing the electromagnetic field in weak fluctuating multilayered media with source is developed. In the theory, the source can be placed in an arbitrary layer among N-layers of the media. On the assumption that every layer among N-layers of the background media is isotropic and varies sufficiently slowly along the vertical position, the average and scattering fields represented by their reflection cofficients, transmission coefficients, impedances and wave number ratios are obtained by W. K. B method and the dyadic Green's function of electric and magnetic typed.
Based on the Born approximation, an analytical theory for computing the electromagnetic field in weak fluctuating multilayered media with source is developed. In the theory, the source can be placed in an arbitrary layer among N-layers of the media. On the assumption that every layer among N-layers of the background media is isotropic and varies sufficiently slowly along the vertical position, the average and scattering fields represented by their reflection cofficients, transmission coefficients, impedances and wave number ratios are obtained by W. K. B method and the dyadic Green's function of electric and magnetic typed.
1988, 10(2): 180-185.
Abstract:
In this paper, the transformation of an exterior of a simply-connected region into an exterior of a unit circle is made by Melentiev s method and a formula is presented for determining the characteristic impedance of a coaxial transmission line consisting of a circular outer conductor and an irregular inner conductor. The validity of the formula is confirmed by numerical results.
In this paper, the transformation of an exterior of a simply-connected region into an exterior of a unit circle is made by Melentiev s method and a formula is presented for determining the characteristic impedance of a coaxial transmission line consisting of a circular outer conductor and an irregular inner conductor. The validity of the formula is confirmed by numerical results.
1988, 10(2): 186-192.
Abstract:
An optimization design theory and algorithm have been developed for waveguide E-plane metal insert filters. The immediate higher order mode coupling in resonator between the discontinuities, which reduces the stop band attenuation for higher frequencies is taken into account. An optimized design filter has been fabricated and tested in low X-band. Good agreement with design has been obtained.
An optimization design theory and algorithm have been developed for waveguide E-plane metal insert filters. The immediate higher order mode coupling in resonator between the discontinuities, which reduces the stop band attenuation for higher frequencies is taken into account. An optimized design filter has been fabricated and tested in low X-band. Good agreement with design has been obtained.
