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1988 Vol. 10, No. 5
Display Method:
1988, 10(5): 385-391.
Abstract:
Based on the theory of generalized function, the validity of interchanging operators method in solving dyadic Green s functions is proved and a universal method for evaluating dyadic Green s functions is developed. Dyadic Green s functions in rectangular waveguide, as examples, are evaluated by this method.
Based on the theory of generalized function, the validity of interchanging operators method in solving dyadic Green s functions is proved and a universal method for evaluating dyadic Green s functions is developed. Dyadic Green s functions in rectangular waveguide, as examples, are evaluated by this method.
1988, 10(5): 392-399.
Abstract:
The dispersion characteristics of a class of closed dielectric waveguide areinvestigated by the method which combines the building-block approach of multimode network theory with rigorous mode matching procedure. Several numerical examples for different guiding structures have been given by the approach. The same structures are also analyzed with the finite element method and the EDC method for comparison. The calculations show that the present approach yields as highly accurate results as the finite element method while almost retaining the simplicity of the EDC method, and justify the utility of the present method.
The dispersion characteristics of a class of closed dielectric waveguide areinvestigated by the method which combines the building-block approach of multimode network theory with rigorous mode matching procedure. Several numerical examples for different guiding structures have been given by the approach. The same structures are also analyzed with the finite element method and the EDC method for comparison. The calculations show that the present approach yields as highly accurate results as the finite element method while almost retaining the simplicity of the EDC method, and justify the utility of the present method.
1988, 10(5): 400-407.
Abstract:
A new modeling filtering method for tracking manoeuvring targets is presented. The manoeuvring accelaration of target is treated as a state variable in the model and then estimated directly. The occurences of target maneuvres are detected by the residue of the Kalman filter. As soon as the manoeuvres found, the algorithm of Kalman filter is restarted so as to adapt the filter to the jumps of manoeuvring accelaration. The enw adaptive filtering method may be thought of optimum in the case. The computing time is much less than that of Moose's method while the filtering accuracy in both cases is nearly the same as shown in the computer simulation.
A new modeling filtering method for tracking manoeuvring targets is presented. The manoeuvring accelaration of target is treated as a state variable in the model and then estimated directly. The occurences of target maneuvres are detected by the residue of the Kalman filter. As soon as the manoeuvres found, the algorithm of Kalman filter is restarted so as to adapt the filter to the jumps of manoeuvring accelaration. The enw adaptive filtering method may be thought of optimum in the case. The computing time is much less than that of Moose's method while the filtering accuracy in both cases is nearly the same as shown in the computer simulation.
1988, 10(5): 408-420.
Abstract:
In order to broaden the bandwidth of a microtrip patch antenna, a broadband two-port feeding technique based on the principle of reactance compensation is suggested. The principle and some design guidelines are presented; the calculation model of a practical configuration as well as its parameter optimization is demonstrated, followed by several kinds of test models and their experimental results. It is shown that this technique enables the VSWR bandwidth to be broaden to 2-3 or more times than that of the conventional design for both linear and circular polarzation operatons.
In order to broaden the bandwidth of a microtrip patch antenna, a broadband two-port feeding technique based on the principle of reactance compensation is suggested. The principle and some design guidelines are presented; the calculation model of a practical configuration as well as its parameter optimization is demonstrated, followed by several kinds of test models and their experimental results. It is shown that this technique enables the VSWR bandwidth to be broaden to 2-3 or more times than that of the conventional design for both linear and circular polarzation operatons.
1988, 10(5): 421-429.
Abstract:
It is important to solve the nth order Volterra kernel or nonlinear transfen , function in describing nonlinear network by Volterra series. Based on the auxiliary algebraic expression of the Volterra series, in this paper, an algebraic algorithm is proposed to evaluate the nth order Volterra kernel and nonlinear function in regular, triangular and sym-metric forms. In addition, the complexity of the algebraic algorithm is reduced.
It is important to solve the nth order Volterra kernel or nonlinear transfen , function in describing nonlinear network by Volterra series. Based on the auxiliary algebraic expression of the Volterra series, in this paper, an algebraic algorithm is proposed to evaluate the nth order Volterra kernel and nonlinear function in regular, triangular and sym-metric forms. In addition, the complexity of the algebraic algorithm is reduced.
1988, 10(5): 430-438.
Abstract:
A scanning electron probe is used to study the secondary emission property of the impregnated barium scandate dispenser cathode, the influence of the activation on the secondary emission property, the secondary emission image and the secondary emission distribution over the surface of the cathode. At optimal activity, m =3.56, Epm= 700eV. The activation has larger effect on the when the activation temperature is higher than 1100℃. The distribution over the surface of the cathode is non-uniform. The half-peak width of the distribution curve over the surface is 0.4. The experimental phenomena are discussed in relation to the surface analysis of the cathode, Thbe theoretically derived binomial distribution curves over the surface are better fitted with the experminental results.
A scanning electron probe is used to study the secondary emission property of the impregnated barium scandate dispenser cathode, the influence of the activation on the secondary emission property, the secondary emission image and the secondary emission distribution over the surface of the cathode. At optimal activity, m =3.56, Epm= 700eV. The activation has larger effect on the when the activation temperature is higher than 1100℃. The distribution over the surface of the cathode is non-uniform. The half-peak width of the distribution curve over the surface is 0.4. The experimental phenomena are discussed in relation to the surface analysis of the cathode, Thbe theoretically derived binomial distribution curves over the surface are better fitted with the experminental results.
1988, 10(5): 439-442.
Abstract:
Spontaneous radiation from a sigle pulse electron beam in a free electron, laser (FEL) with a helical magnetic field is investigated by using Green s function. It is shown that there is self-interference caused by a finite length of the pulse beam.
Spontaneous radiation from a sigle pulse electron beam in a free electron, laser (FEL) with a helical magnetic field is investigated by using Green s function. It is shown that there is self-interference caused by a finite length of the pulse beam.
1988, 10(5): 443-448.
Abstract:
In this paper, a scheme of an auto-tracking antenna is given to replace the complex nutating conical-scan antenna. The measured values of the feed and antenna show that the angles of the beam deviated from the antenna axis in any plane are almost the same and the polarization performance is excellent. In tracking the signal target with linear polarization, the target is catched out quickly and exactly, and the situation of the antenna is stable.
In this paper, a scheme of an auto-tracking antenna is given to replace the complex nutating conical-scan antenna. The measured values of the feed and antenna show that the angles of the beam deviated from the antenna axis in any plane are almost the same and the polarization performance is excellent. In tracking the signal target with linear polarization, the target is catched out quickly and exactly, and the situation of the antenna is stable.
1988, 10(5): 449-453.
Abstract:
A theory is presented for frequency responses of backfire helical antenna. Based on assumption of single travelling wave of current, the approximate analytical solution of far field is obtained by summing the contributions of the current distribution. The analytical results are consistent with H. Nakano s numerical results. A new type of reflecting antenna, whose feed is a backfire helix and whose reflector is a conductive disk, is investigated by using this theory. The results are available to practical applications.
A theory is presented for frequency responses of backfire helical antenna. Based on assumption of single travelling wave of current, the approximate analytical solution of far field is obtained by summing the contributions of the current distribution. The analytical results are consistent with H. Nakano s numerical results. A new type of reflecting antenna, whose feed is a backfire helix and whose reflector is a conductive disk, is investigated by using this theory. The results are available to practical applications.
1988, 10(5): 454-461.
Abstract:
General formulae for the equivalent circuit parameters of multi-fin-line structures are derived by using field matching technique and eigenvalue concept. Several inductive fin-line structures are analysed with this formula. Inductive parameters of the equivalent circuit of these structures decrease as the number of the fins increases and the thickness of the fins becomes greater. When frequency goes higher, the circuit parameters x, and xp become bigger. The parameters decrease as the distances between each two metal fins gocs further apart. With different moe number considered in the computation, the inductive parameters of dielectric fin (r=2.22) sandwiched in two metal sheets are analysed. The results show that then the mode number in continuous region and discontinuous region are greater than 20 and 80 respectively, errors due to truncation are less than 1%. In the case of single metal inductive fin and dielectric fin sandwiched in two metal sheets, the calculated data with this method are in good agreement with those calculated by variation method and S parameter method respectively.
General formulae for the equivalent circuit parameters of multi-fin-line structures are derived by using field matching technique and eigenvalue concept. Several inductive fin-line structures are analysed with this formula. Inductive parameters of the equivalent circuit of these structures decrease as the number of the fins increases and the thickness of the fins becomes greater. When frequency goes higher, the circuit parameters x, and xp become bigger. The parameters decrease as the distances between each two metal fins gocs further apart. With different moe number considered in the computation, the inductive parameters of dielectric fin (r=2.22) sandwiched in two metal sheets are analysed. The results show that then the mode number in continuous region and discontinuous region are greater than 20 and 80 respectively, errors due to truncation are less than 1%. In the case of single metal inductive fin and dielectric fin sandwiched in two metal sheets, the calculated data with this method are in good agreement with those calculated by variation method and S parameter method respectively.
1988, 10(5): 462-468.
Abstract:
The frequency characteristics of multilayered broadside, edge-coupled mul-timicrostrip llines are analyzed by using spectral domain immittance approach. The design curves about characteristic impedances and effective dielectric constants are given for three-layered broadside, edge-coupled microstrip lines. It is shown that the even-odd mode impedance changes rapidly with frequency, especially when the dielectric constant r is small.
The frequency characteristics of multilayered broadside, edge-coupled mul-timicrostrip llines are analyzed by using spectral domain immittance approach. The design curves about characteristic impedances and effective dielectric constants are given for three-layered broadside, edge-coupled microstrip lines. It is shown that the even-odd mode impedance changes rapidly with frequency, especially when the dielectric constant r is small.
1988, 10(5): 469-473.
Abstract:
An adjustable permanent magnetic circuit that is staked by three layers of samarium-cobalt permanent magnets magnetized in radial direction and magnetic conductive material such as iron, is developed. By means of CAD, a uniform magnetic field distribution having flux density of 1.2 kGs on the axis and a fluctuation of 0.7% within the axial length of 270 mm is achieved. It is a good magnetic circuit for permanent magnetic focusing system of high power microwave tubes.
An adjustable permanent magnetic circuit that is staked by three layers of samarium-cobalt permanent magnets magnetized in radial direction and magnetic conductive material such as iron, is developed. By means of CAD, a uniform magnetic field distribution having flux density of 1.2 kGs on the axis and a fluctuation of 0.7% within the axial length of 270 mm is achieved. It is a good magnetic circuit for permanent magnetic focusing system of high power microwave tubes.
1988, 10(5): 474-480.
Abstract:
High temperature (750-1900℃) annealing behaviour of NTD CZ Si irradiated by high neutron fluence (1018 n/cm) is investigated. It is found that neutron irradiation induced donor (NIID) with high concentration can be produced within the temperature range, die highest concentration of the donors can arrive in value about 1016cm-3. Only if annealing temperature exceeds 1100℃, the accurate aim rwistivity can be obtained. The annealing technology for the NTD CZ Si and the condition of appearance and annihilation for NIID are studied.
High temperature (750-1900℃) annealing behaviour of NTD CZ Si irradiated by high neutron fluence (1018 n/cm) is investigated. It is found that neutron irradiation induced donor (NIID) with high concentration can be produced within the temperature range, die highest concentration of the donors can arrive in value about 1016cm-3. Only if annealing temperature exceeds 1100℃, the accurate aim rwistivity can be obtained. The annealing technology for the NTD CZ Si and the condition of appearance and annihilation for NIID are studied.
