Autostochastic ring system of triggers connected through integrating circuits

A ring system of triggers connected to one another by integrating circuits is studied. Equations for a multiple-trigger ring systems are given, and the results of a numerical analysis for a system containing three triggers are presented. It is shown that chaotic oscillations with switching between two basins of attraction are excited in the ring system considered. The possibility of controlling chaotic oscillations is demonstrated.     

Method of complex-conjugate matching of microwave noise generators

Translated from Izmeritel'naya Tekhnika, No. 7, pp. 48–50, July, 1988.     

Long-lived explosive-emission cathode for high-power microwave radiation generators

The operation of cold explosive-emission cathodes having a current density of ∼10⁴ A/cm², fabricated using various materials, was investigated under a large number of switching cycles. The cathode voltage was ∼500 kV, the maximum current ∼5 kA, and the pulse duration ∼20 ns. It is shown that when the number of switchings is small (⩽10³ pulses), cathodes having similar geometry exhibit similar emission properties. For most of the materials studied, as the number of switching cycles increases (⩾10³ pulses), the current rise time increases (as far as the pulse duration) and the maximum vacuum diode current decreases. When a graphite cathode was used, the maximum current remained unchanged up to 10⁸ switching cycles. The mass removed from the cathode was determined for various materials. The results were used to achieve continuous operation of a relativistic 3 cm backward-wave tube having an output power of 350–400MW and an almost constant power level during 10⁸ pulses at a repetition frequency of 100–150 Hz. Pis’ma Zh. Tekh. Fiz. 25, 84–94 (November 26, 1999)     

Ultrabroadband generators of noiselike high-frequency and microwave oscillations with electron feedback

It is experimentally established that oscillators, such as a low-voltage vircator with electron feedback, are characterized by an ultrabroad generation band (up to four octaves and above). The minimum frequency of oscillations is on the order of 50 MHz, while the maximum frequency is about 3–3.5 GHz. The low-frequency part of the spectrum is related to the oscillations of positive ions in the interaction space.     

Boundary of generalized synchronization in two unidirectionally coupled tunnel diode generators

The boundary of generalized synchronization regimes in a system of two unidirectionally coupled oscillators based on tunnel diodes has been studied. Peculiarities in the behavior of the boundary are found in the region of relatively large detunings between eigenfrequencies of the two subsystems. The character of this behavior and physical mechanisms leading to the onset of generalized synchronization regimes in the system are explained based on the analysis of evolution of the spectrum of oscillations in the response subsystem.     

Studying dynamic chaos in microwave ring generators based on normally magnetized ferromagnetic film

Technical Physics Letters - We present results of an experimental investigation of the transition to a microwave dynamic chaos regime in ring oscillators based on normally magnetized yttrium iron...     

High-power microwave pulses generated by a resonance relativistic backward wave oscillator with a power supply system based on explosive magnetocumulative generators

High-power microwave radiation has been generated using a relativistic backward wave oscillator (BWO) powered by a high voltage source comprising an inductive energy storage and an electric-explosion current switch. The high voltage source and the BWO magnetic system are energy pumped by explosive magnetocumulative generators. In experiments, the proposed setup generated 30-ns single-mode radiation pulses with a carrier frequency of 3.6 GHz at an output power of 0.75 GW.     

Degradation of pentachlorophenol with zero-valence iron coupled with microwave energy

The objective of this research is to study the degradation of pentachlorophenol with zero-valence iron (Fe(0)) coupled with the use of microwave energy. The sample containing 1000 mg/L PCP solution was dosed with 0.5 g Fe(0) and then subject to 700 W microwave energy for 10s; 85% pentachlorophenol was noted to be removed. If the microwave treatment time was increased to 30s, the pentachlorophenol removal efficiency exceeded 99% with end products including H(2)O, CO(2), HCl, etc. Using Fe(0) as a medium, the microwave treatment is made an efficient method for degrading pentachlorophenol. The time needed to achieve a satisfactory treatment is also reduced leading to significant savings of energy consumption to make this method cost-effective. Since this technology applies Fe(0), which is amenable to natural environment, to speed up the decomposition of an industrial solvent, it is not only cost-effective but also environmental friendly for the industry to pursuit sustainable development.     

Effects of microwave radiation on two strongly coupled indium microbridges

Effects of incident microwave radiation on two closely spaced indium micro-bridges are investigated by measuring the current-voltage(I–V) characteristics of the weak links, using microprobes prepared by an electron beam lithography technique. Pronounced distortions as well as negative dynamic resistance are found in theI–V curves where the sum of the two Josephson frequencies is equal to the incident microwave frequency or its harmonics. These results are interpreted in terms of interactions of the weak links with the microwave radiation and with each other via exchange of quasiparticles.Research supported in part by the National Science Foundation.     

Wideband chaotic microwave signal generation in a ring system with a nonlinear delay line on coupled ferromagnetic films

Various regimes of chaotic signal generation have been studied in an self-oscillating ring system with a wideband nonlinear delay line based on coupled ferromagnetic films, in which magnetostatic backward volume waves (MSBVWs) are excited. It is shown for the first time that the simultaneous excitation of two waves in the coupled films leads to the appearance of a falling part in the dynamic characteristic of the MSBVW delay line and the generation of a broadband chaotic signal with a continuous spectrum. Under certain conditions, the ring exhibits a regime of intermittency, in which broadband chaotic signals with both continuous and discrete spectra are generated.     

Single- and dual-passband microwave planar filters with coupled double-transmission-line resonators

A type of planar double-transmission-line resonator, consisting of two open-ended half-wavelength transmission-line segments edge inter-coupled along their entire length, is proposed. This microwave resonator, because of the generation of double resonances, allows coupled-line bandpass filters with reduced longitudinal length to be implemented. This is the main contribution of this work. Furthermore, as an added feature of the aforementioned resonator, its two-line geometry makes it suitable for dual-band bandpass filter design. To prove the concept experimentally, two different examples of single- and one dual-passband microstrip filter prototypes within the 1-1.5 GHz range are synthesised, constructed and tested. The major advantages of these filter solutions are emphasised. A complementary section dealing with the analysis of the split-type double-transmission-line resonator is also reported. Here, as a result of this study, formulas for its exact design are provided for the first time.     

一种有源微波近场成像系统

针对早期乳腺癌检测等近场目标的探测成像,设计了一种基于2.45GHz连续波信号的微波近场成像实验系统,主要由硬件电路和成像算法组成.系统电路用小体积、高性能和低成本的射频微波集成芯片实现,大大缩小了系统的体积并降低了成本,电路由天线模块、收发模块和数据采集控制模块构成.成像算法采用有限元微波共焦算法,完成对被测区域日标的探测成像.     

微波元器件自动测试系统

为了提高微波元器件的测试效率,保证测试的一致性,研发了微波元器件入检自动测试系统,使用计算机在外部执行测试程序来控制矢量网络分析仪,从而实现自动化测试.该自动测试系统中矢量网络分析仪采用的是美国Agilent公司生产的8722ES,通过该仪器上的GPIB接口,使用熟悉的SCPI命令创建程序,利用Visual Basic 6.0程序语言进行软件编译.实践证明,该测试系统运行程序可靠,可显著提高器件检测的效率和准确性.     

船舶发电机组负荷突加突卸测试系统设计

针对船舶发电机组负荷突加突卸时间短、波动大、不易测量的状况,采用NI公司的数据采集卡USB6009为核心构建了船舶发电机组测试系统的硬件。基于LabVIEW开发环境,研究了其软件设计并作了相应的实验验证了该系统的可行性与有效性。实验表明,该测试系统界面友好,性能稳定,有良好的实时性和测量精度。     

弦-梁耦合系统的动力学行为分析

本文研究了弦-梁耦合系统在初始平衡解处的稳定性与分岔情况,给出了特征值随阻尼参数的变化情况,并利用稳定性分析和特征值分析等解析方法,得到了初始平衡解、周期解和拟周期解的稳定边界以及导致Hopf分岔和2维胎面等分岔解的临界分岔曲线。最后,利用数值模拟方法研究了弦-梁耦合系统的稳定性与分岔情况。     

结构声腔耦合系统的频率耦合机理探讨

给出结构和声腔耦合系统的振型耦合特点,选择几阶典型结构声腔模态,计算分析耦合系统固有频率的分布特性;分析论证耦合系统固有频率的主导特性判断准则;基于该准则深入分析耦合系统固有频率的主导特性,从而揭示结构声腔的频率耦合机理。