A computerized technique including time sampling and phase adjustment is developed for wideband radar array imaging. Algorithms are given for examination of errors due to time sampling, FFT is introduced to speed up the imaging processing with a periodic array. Simulation results aud experimental data are included to show the feasibility of the technique.

Binary Goppa codes are a large and powerful family of error-correcting codes. But how to find the true minimum distance of binary Goppa codes is not yet solved. This paper will give derivation of a new lower bound for the minimum distance of binary Goppa codes. This new lower bound improves the results obtained by Y. Sugiyama et al. (1976) and Feng Guiliang (1983). The method in this paper can be generalized for other Goppa codes easily.

The Mixed Time and Frequency Decimation FFT Algorithm (MDFFT) proposed by K. Nakayama is simplified and deepened, then a new FFT algorithm based on tree-decomposition process is developed. The number of real multiplications of the newalgorithm is about (65/64)Nlog₂N-3N-4 which is less than (3/2)Nlog₂N-7N+10N^1/2-4 of MDFFT.

On the basis of the equation of the Fresnel-Kirchhoff scalar diffraction field, the impulse responses of parallel-fed and series-fed rectangular antennas with separable aperture distributions and the impulse responses of parallel-fed and center-series-fedcircular antennas with circularly symmetric distributions are derived——all of themcan be expressed in the aperture amplitude distributions.

An accurate solution of characteristie impedance of the elliptic strip-line with conformal transformation is developed. Some data are given, which are useful for designing elliptic strip-lines.

A new method is presented to calculate the field distribution in the channel guide-using Weber-Schafheitlin integral and field matching method. Some numerical results are given for several cases. Thus we can get a elear view about the field distribution in the channel guide.

Spreading band with negative feedback is a valid method that is presently widely used at home and abroad. From developing the modulation summator of microwave phase modulator, it is found that the modulation summator presented in this paper seems to bp an another valid method of spreading band. The gain-band product of the latter is much larger than that of the former.The new modulation summator preseuted in this paper has a much wider band, higher non-distorted output voltage aud better rejection capability to combined-wave than Goddard tracking system developed by Motorola Co. Its characteristics are analysed in detail with the flow-graph. A series of formulas are derived. It is found that the theoretical analysis agrees well with experimental curve. Its circuits are very simple and work stably within the temperature of —40—+85℃.

We presented the measurements of two-dimensional far-field pattern of antennas, which are going to be used in Miyun synthetie-aperture radio telescope. The patterus were measured by means of interferential method with the quiet sun. The measured results were compareal with the calculated ones.

Fourier transform iterative method for synthesizing a pattern is recently proposed by Feng (1980). The accuracy and effieiency of the method are analyzed, and the result shows that in the shaped region, Fourier transform iterative method will converge to a desired shape, but the energy beyond the shaped region will increase as tha iterative number becomes larger. As example, synthesizing δ function by the method is given.

A matched filter using CCD for PCM is made. The experimental results of output waveform, transfer function and output signal-to-noise ratio are given and comparisons are made with the theoretical results. The non-return-to-zero codes are realized with the output signal-to-noise ratio being 1 dB below the theoretical value.

The general expressions of the spatial growth rate and temporal growth rate in a gvrotron are derived, and it shows that they are equivalent in calculating the phase shift and amplitude growth of the electromagnetic wave.