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1984 Vol. 6, No. 5
Display Method:
1984, 6(5): 343-350.
Abstract:
The approach for the Jacobi-Bessel series expansion of the physical opties radiation integral studied by R. Mittra et al. is extended to the case of eireularly polarized illumination, and a computation technique for the eireularly polarized contoured beam of the offset reflector antennas is analysed. This paper deals with the following pro-blems: the mathematical model of eireularly polarized feed, the equivalent distribution of reflector projected aperture, the secondary radiation field formula of offset parabolid reflector and the EIRP computation formula of the contoured beam. The EIRP/W contour-plot for the western zone coverage of the territory of China is given (illumination by 7-element feed array).
The approach for the Jacobi-Bessel series expansion of the physical opties radiation integral studied by R. Mittra et al. is extended to the case of eireularly polarized illumination, and a computation technique for the eireularly polarized contoured beam of the offset reflector antennas is analysed. This paper deals with the following pro-blems: the mathematical model of eireularly polarized feed, the equivalent distribution of reflector projected aperture, the secondary radiation field formula of offset parabolid reflector and the EIRP computation formula of the contoured beam. The EIRP/W contour-plot for the western zone coverage of the territory of China is given (illumination by 7-element feed array).
1984, 6(5): 351-358.
Abstract:
This paper presents a standard program using finite-element method to calculate dispersion characteristics of hybrid dominant and higher order modes in rectangular waveguide filled with arbitrary block-shaped dielectrics. The dispersion characteristics calculated with the program for more than ten different rectangular waveguides loaded with various dielectric distributions verify the reliability of the program. The useful bandwidth of waveguide filled with I-shaped dielectric is analysed in detail. The dispersion curves given in this paper can be used in analysing and designing related microwave components.
This paper presents a standard program using finite-element method to calculate dispersion characteristics of hybrid dominant and higher order modes in rectangular waveguide filled with arbitrary block-shaped dielectrics. The dispersion characteristics calculated with the program for more than ten different rectangular waveguides loaded with various dielectric distributions verify the reliability of the program. The useful bandwidth of waveguide filled with I-shaped dielectric is analysed in detail. The dispersion curves given in this paper can be used in analysing and designing related microwave components.
1984, 6(5): 359-365.
Abstract:
A noval dielectrie waveguide structure suitable for millimeter-wave integrated circuits, called trapped hollow image guide, is described. A method of analyzing wave propagation in this structure is developed by using effective dielectric constant approach and surface impedances. The numerical results and discussion are given.
A noval dielectrie waveguide structure suitable for millimeter-wave integrated circuits, called trapped hollow image guide, is described. A method of analyzing wave propagation in this structure is developed by using effective dielectric constant approach and surface impedances. The numerical results and discussion are given.
1984, 6(5): 366-372.
Abstract:
A general approach is presented for the frequency-domain analysis of SC networks. At first, the sealing property of SC network is discussed. From the scaling property it is pointed out that the SC network ean be modeled by an analogue circuit consisting of amplifiers, resisters and capacitors with real constant element values using sealing-Pauper's algorithm. Thus, the SC network frequency response and sensitivity can be found by using available Standard analogue circuit analysis program.
A general approach is presented for the frequency-domain analysis of SC networks. At first, the sealing property of SC network is discussed. From the scaling property it is pointed out that the SC network ean be modeled by an analogue circuit consisting of amplifiers, resisters and capacitors with real constant element values using sealing-Pauper's algorithm. Thus, the SC network frequency response and sensitivity can be found by using available Standard analogue circuit analysis program.
1984, 6(5): 373-381.
Abstract:
A gain control loop which operates in a digital correlating receiver is described. The properties of the loop are analysed mathematically and the formulas to determine the sensibility and other parameters are derived. The static and dynamic features of some examples are shown. The procedure for design such a gain control loop is discussed.
A gain control loop which operates in a digital correlating receiver is described. The properties of the loop are analysed mathematically and the formulas to determine the sensibility and other parameters are derived. The static and dynamic features of some examples are shown. The procedure for design such a gain control loop is discussed.
1984, 6(5): 382-390.
Abstract:
Using the clockwise or anticlockwise stepping pulse code signal, the characterities of general QPSK modulation are analysed. The spectrums in several operational conditions and the admittance formulas of related two modulation circu ts are given. Several typical examples of QPSK modulation are calculated. The results are used to decide the modulation effect and phase error, and also to adjust the QPSK modulator under the dynamic testing. The experimental results are in agreement with the theortical calculations. An X band QPSK modulator is also presented. the maximum phase error is less than 4, insertion loss less than 4 dB, phase accuracy near 0.1 and transmission data rate up to 34 Mb/s.
Using the clockwise or anticlockwise stepping pulse code signal, the characterities of general QPSK modulation are analysed. The spectrums in several operational conditions and the admittance formulas of related two modulation circu ts are given. Several typical examples of QPSK modulation are calculated. The results are used to decide the modulation effect and phase error, and also to adjust the QPSK modulator under the dynamic testing. The experimental results are in agreement with the theortical calculations. An X band QPSK modulator is also presented. the maximum phase error is less than 4, insertion loss less than 4 dB, phase accuracy near 0.1 and transmission data rate up to 34 Mb/s.
1984, 6(5): 391-399.
Abstract:
A comparison of the performances of two algorithms-least mean square (LMS) and modified time domain orthogonality (MTDO) for an adaptive filter is made. Computer simulations of these two algorithms show that MTDO has an important advantage, that is, the same convergenee factor can be used within wider range of signal to noise ratio of input signal in noise caneeller and line enhancer. MTDO adaptive noise caneeller has a useful characteristic, that is, at the same signal to noise ratio, the power of input reference signal is not correlated with the convergence factor. The comparison of convergence value of mean square error (MSE) of both LMS and MTDO with theoretical minimum value of MSE is given. The performances of spectral estimates of LMS and MTDO adaptive system are obtained experimentally.
A comparison of the performances of two algorithms-least mean square (LMS) and modified time domain orthogonality (MTDO) for an adaptive filter is made. Computer simulations of these two algorithms show that MTDO has an important advantage, that is, the same convergenee factor can be used within wider range of signal to noise ratio of input signal in noise caneeller and line enhancer. MTDO adaptive noise caneeller has a useful characteristic, that is, at the same signal to noise ratio, the power of input reference signal is not correlated with the convergence factor. The comparison of convergence value of mean square error (MSE) of both LMS and MTDO with theoretical minimum value of MSE is given. The performances of spectral estimates of LMS and MTDO adaptive system are obtained experimentally.
1984, 6(5): 400-408.
Abstract:
A set of programs is estabilished for IMPATT Diode Simulation. It can be used to calculate the DC small signal and large signal solution of the IMPATT diodes made of different materials and having different doping profiles. The physical principles, numerical methods and program designs are discussed, and the half-implicit method is presented in detail. Those programs can be used to simulate all kinds of transit-time devices, but only the calculating results of Si IMPATT Diode are given.
A set of programs is estabilished for IMPATT Diode Simulation. It can be used to calculate the DC small signal and large signal solution of the IMPATT diodes made of different materials and having different doping profiles. The physical principles, numerical methods and program designs are discussed, and the half-implicit method is presented in detail. Those programs can be used to simulate all kinds of transit-time devices, but only the calculating results of Si IMPATT Diode are given.
1984, 6(5): 409-416.
Abstract:
The relation betweem the frequency stability due to the flicker phase noise (phase power spectrum density S△(f) in frequency domain and Allen variance y2() in time domain) and the parameters of the transistors have been derived and experimen-tally verified.
The relation betweem the frequency stability due to the flicker phase noise (phase power spectrum density S△(f) in frequency domain and Allen variance y2() in time domain) and the parameters of the transistors have been derived and experimen-tally verified.
1984, 6(5): 417-421.
Abstract:
A density-of-state distribution in the pseudo-gap of phosphorus-doped a-Si:H material prepared by GD method has been measured experimentally by deep level tran-sient spectroscopy (DLTS). A minimum value of 71015cm-3 eV-1 has been obtained at the energy of about 0.45 eV below Ec. This physical picture is quite different from the previous one obtained by the field effect method. Some comments on the method used and the theoretical analysis are given.
A density-of-state distribution in the pseudo-gap of phosphorus-doped a-Si:H material prepared by GD method has been measured experimentally by deep level tran-sient spectroscopy (DLTS). A minimum value of 71015cm-3 eV-1 has been obtained at the energy of about 0.45 eV below Ec. This physical picture is quite different from the previous one obtained by the field effect method. Some comments on the method used and the theoretical analysis are given.
1984, 6(5): 422-424.
Abstract:
The detection performance of the frequency-domain adaptive filter is compared with the time-domain one, Comparisons are based on the computer digital simulation with a sinusoidal signal and white Gauss noise. The performance of the frequency and time-domain adaptive filters are shown to be the same for an unknown frequency signal, but for the detection of known frequency the frequency-domain adaptive filter length is much shorter to get the same detection probability.
The detection performance of the frequency-domain adaptive filter is compared with the time-domain one, Comparisons are based on the computer digital simulation with a sinusoidal signal and white Gauss noise. The performance of the frequency and time-domain adaptive filters are shown to be the same for an unknown frequency signal, but for the detection of known frequency the frequency-domain adaptive filter length is much shorter to get the same detection probability.
