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Effects on Sum and Difference patterns by Adaptive Null

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Journal of Systems Engineering and Electronics 1994年第1期5卷 15-23页

作者： Xie Lianggui and Jiang Xinfa(beijing institute of radio measurement, p. o. box 3923, beijing 100854, china) beijing institute of radio measurement P. O. Box 3923 Beijing 100854 China

This paper presents a simple method of forming sum and difference patterns with adaptivenulls. The effects on the sidelobe level and the pointing null of difference pattern by adaptive null areanalyzed. The result that the increment value of the envelope of the sidelobe level under the effect ofa null is less than l.6dB is proved. The formula about shift value of the pointing null which is thefunction of the jammer direction and array parameters is given in the paper.

关键词： Adaptive null Sum and difference patterns Shift value of the pointing null.

Numerical Techniques Used in Modeling Codes for Dual-Reflector Antenna Design and Analysis

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Journal of Systems Engineering and Electronics 1993年第2期4卷 63-74页

作者： Wang Welling, Wang Shijin and Chen Jingxiongbeijing institute of radio measurement, p. o. box 3923, beijing 100854, china beijing institute of radio measurement P. O. Box 3923 Beijing 100854 China

An user-oriented computer software consisting of three modeling codes, named DRAD, DRAA and FDpAT, is introduced. It can be used to design three types of Cassegrain system: classical, with shaped subreflector and with dual shaped reflectors, and to analyse radiation patterns for the antennas. Several mathematical models and numerical techniques are presented.

关键词： Software Numerical technique Antenna Dual-reflector antenna Cassegrain system.

Input Admittance and Current Distribution of Infinitely Long Circular Cylindrical Antenna Driven at Center

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Journal of Systems Engineering and Electronics 1991年第2期2卷 73-81页

作者： Jinxion Chen & Guotai Yinbeijing institute of radio measurement, p.o.box 3923, beijing 100854, china beijing institute of radio measurement P.O. Box 3923 Beijing 100854 China

In this paper, by change of integration path in complex spectrum domain and by defining input admittance as the ratio of complex radiated power to amplitude of square of voltage across the gap, new expressions of admittance (valid for all frequencies ) of infinitely long cylindrical antenna with and without conducting ground are obtained. Meanwhile corresponding formulas of current distribution are derived in detail. Some numerical computations are also given.

关键词： Input admittance Current distribution Long cylindrical antenna.

A Ku and Ka Dual Band Experimental Radar

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Journal of Systems Engineering and Electronics 1991年第2期2卷 124-128页

作者： Li Jiliang and Xie Zhanaobeijing institute of radio measurement, p.o.box 3923, beijing 100854, china beijing institute of radio measurement P.O. Box 3923 Beijing 100854 China

Due to the good performance of tracking low elevation target as compared to microwave and the superiority in penetrating smoke, dust, fog, and dry snow as compared to infrared, a Ku and Ka dual band experimental radar was designed and developed. This Ku and Ka dual band experimental radar is an arnplitute-comparison monopulse tracking and guiding radar. The constitution and parameters of this radar is described in paragraph 2. paragraph 3 deals with two experiments for testing the tracking performances against low elevation target, and gives the important results. Both Ku and Ka band have high tracking precision when they track high elevation targets, while Ka band has much better tracking performance than Ku band when they track low elevation targets. Ka band can track a helicopter, whose radar cross section is about 6 square meters, at 40m, 20m, 10m, and even 5m above sea. Ku band can only track the same helicopter at 160m and higher above sea.

关键词： Millimeter wave radar Ku and Ka band radar.

Wind measurement with a Wind profiling Radar

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Journal of Systems Engineering and Electronics 1991年第1期2卷 81-88页

作者： Qi Rundong, Huang Changcheng and Tian Wenbin beijing institute of radio measurement, p. o. box 3923, beijing 100854, china beijing institute of radio measurement P. O. Box 3923 Beijing 100854 China

The first troposphere wind profiling radar in china has been in operation. The paper describes the radar parameters and characteristics with some experimental results presented.

关键词： pulsed Doppler radar Wind profiler Wind measurement.

An Analysis of Mutual Interference in Radar Systems Using Dual-Band (Ka / X) Antennas

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Journal of Systems Engineering and Electronics 1992年第4期3卷 84-87页

作者： DU Shimin, beijing institute of radio measurement, p.o.box 3923-2, beijing 100854, china WANG Baofa, beijing University of Aeronautics and Astronautics, beijing, china WU Yi, No.2 radio Instrument Factory of beijing, beijing, china

An analysis of mutual interfering sources on RF systems using dual-band (Ka / X) radar is presented. The purpose of this paper is to improve operational performance of the system from the point of view of EMC design. ... 详细信息

关键词： Antennas Ka An Analysis of Mutual Interference in Radar Systems Using Dual-Band

A numerical simulation strategy for a compressor’s underlying axisymmetric characteristic and its application in body force model

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Chinese Journal of Aeronautics 2024年第8期37卷 79-90页

作者： Shijie LIU Tianyu pan Qiushi LI School of Energy and power Engineering Beihang UniversityBeijing 100191China Research institute of Aero-Engine Beihang UniversityBeijing 100191China Key Laboratory of Fluid and power Machinery Ministry of EducationXihua UniversityChengdu 610039China

Accurate prediction of the aerodynamic response of a compressor under inlet distortion is crucial for next-generation civil aircraft,such as Boundary Layer Ingestion(BLI)silent ***,research on the Body Force(BF)model plays a significant role in achieving this ***,distorted inlet airflow can lead to varying operating conditions across different spatial locations of the compressor,which may cause some regions to operate outside the stability ***,the accuracy of BF model simulations might be *** address this issue,this paper proposes a numerical simulation strategy for acquiring the steady axisymmetric three-dimensional flow field of a compressor operating at low mass flow rates,which is known as the Underlying Axisymmetric pressure Rise Characteristic(UApRC).The proposed simulation accounts for two different rotor speeds of a transonic compressor and identifies initial positions in the flow field where deterioration occurs based on prior experimental ***,simulation results are incorporated into the BF model to replicate hub instability observed in *** results demonstrate that this strategy provides valid predictions of the UApRC of the compressor,thereby addressing the limitations associated with the BF model.

关键词： Compressor partial instability performance at low mass flow rates Underlying axisymmetric pressure rise characteristic Novel simulation strategy Body force model

on a Monopulse Ring-Focus Shaped Reflector Antenna with Arbitrary polarization

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Journal of Systems Engineering and Electronics 2002年第1期13卷 59-67页

作者： Cheng Zhen & Lü Shanwei beijing University of Aeronautics and Astronautics, beijing 100083, p.R. china. Huang Huai & Jiang Xinfa beijing institute of radio measurement, beijing 100854, p.R. china beijing University of Aeronautics and Astronautics Beijing 100083 P. R. China beijing institute of radio measurement Beijing 100854 P. R. China

The near field distribution and far field pattern of a monopulse ring focus shaped reflector antenna are studied. The four fold integral appearing in the formulation by using po method is converted into a triple integral for the near field case and a double integral for the far field case by applying the Fourier series expansion. Good agreements have been achieved between theoretical and experimental results.

关键词： Monopulse Ring focus Near field distribution pattern polarization.

The　Design　of　I/o　Subsystem　in　Satellite　Real-Time　Microkernel　operating　System

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Journal of Systems Engineering and Electronics 1998年第3期9卷 77-81页

作者： Liu Xiaodong & Li Lianzhi (Dept. of Computer Science & Engineering, Harbin institute of Technology, 150001, p. R. china) Qian Chunlai(Beijiing institute of radio measurement, 100854, p. R. china) Dept. of Computer Science Engineering Harbin Institute of Technology 150001 P. R. China beijing institute of radio measurement 100854. P. R. China

one of the most important features of modern minor satellites is to realize autonomous moving. The performance of the satellite autonomous computer operating system acting as the control center is utmost important. The recent trend in operating system development is adopting microkernel architecture which holds such advantages as microminiaturization, modularity, portability and extendibility. The performance of I/o subsystem is currently receiving considerable research attention. object-orientation offers an approach to application development in which software system can be constructed by composing and refining the pre-designed plug-compatible software *** also starts with some basic notions fairly well accepted in computer science, namely encapsulation and reuse. In this paper, a new object-oriented real-time I/o subsystem model has been *** this model, the traditional I/o subsystem framework is discarded and a stream mechanism based on the object-oriented concept is introduced. In addition, the I/o requests are classified according to their time emergency to obtain real-time performance. So, this model meets such satelliteperformance requirements as reliability, flexibility, portability and real-time performance.

关键词： Satellite operating system I/o subsystem object-oriented Real-time