共查询到20条相似文献,搜索用时 31 毫秒
1.
Yonghong Zhang Xiaohong Tang Yong Fan Zhengde Wu 《International Journal of Infrared and Millimeter Waves》2008,29(2):142-147
A W-band coherent stepped-frequency pulsed radar front-end is developed. It consists of a millimetre wave transmitting source,
a mm-wave local source, a DDS with multi frequency points output and two microwave sources serving as local oscillators. All
the sources are coherent with the 120 MHz referenced crystal oscillator. The mm-wave sources are realized by frequency multiplier
chain, up-conversion and injection locking. The phase noise of fundamental-wave injection-locked W-band harmonic Gunn oscillator
output signal achieves −98 dBc/Hz at 10 kHz offset and the spurious output is less than −50 dBc. The received intermediate
frequency signal is also presented. 相似文献
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Ronald K. Cross A.W. Phelps A.D.R. Wenlong He Huabi Yin Spark S.N. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1998,26(3):375-382
Experiments have investigated the behavior of explosive emission cathode gyrotrons using cylindrically symmetric coaxial diodes with centrally located knife-edged cathode and conical anode. Voltage probes and current shunts were exploited to monitor the diode electrical behavior when driven by a 3 μs 1/e time Marx power supply (up to 150 kV). Temporal reference signals permitted comparison of the diode's electrical evolution with the simultaneously measured microwave output signal from the gyrotron. The microwave output pulse duration was found to depend on the diode gap spacing (in the range 16-27 mm), the cavity magnetic field (range 1.3-3.3 T) and the cathode material, the termination being caused by the decay of the accelerating potential across the diode and the disruption of the diode geometry. The ratios of the cathode flare expansion velocities for graphite, copper and stainless steel cathodes were estimated as (1:(1.3±0.2):(2.2±0.5)) with a corresponding change in the duration of the microwave output signal [((590±17):(414±25):(325±10)) ns at 2.6 T]. Preliminary results are reported of recent experiments which have compared the optical emissions from the diode region during pulsed gyrotron operation with the simultaneously recorded diode electrical behavior and the gyrotron microwave output 相似文献
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G.A. Melkov V.I. Vasyuchka A.V. Chumak A.N. Slavin 《Journal of magnetism and magnetic materials》2006
The wave front reversal (WFR) of non-reciprocal waves has been investigated. The experiment was performed using surface magnetostatic waves (SMSW) excited by a pulsed microwave signal of the carrier frequency ∼4.7 GHz in an epitaxial yttrium–iron garnet (YIG) film. The WFR was realized by pulsed parametric pumping of a double frequency. It was shown that WFR with high efficiency can be achieved for SMSW having relatively small wavenumbers k∼102 rad/cm. 相似文献
7.
基于真空二极管设计了一种X波段大功率微波检波器,该检波器主要由真空二极管、BJ-100波导、调谐螺栓、低通滤波器和直流电源组成,其工作频率可根据需要在8.6~9.8GHz范围内调谐。重点阐述该型大功率微波检波器的结构设计、实验室标定及辐射场测量实验结果,研究了不同脉宽和不同灯丝电压与检波特性的依赖关系。实验结果表明:该型检波器具有承受微波脉冲功率高(大于7kW)、响应快(响应时间小于2.0ns)、动态范围大、输出信号幅度高(可达数十V)、不需要同步信号等特点,适用于在高功率微波干扰环境下的单次和高重复频率脉冲功率测量。 相似文献
8.
Experimental investigation of a compact relativistic magnetron with axial TE<sub>11</sub> mode radiation 下载免费PDF全文
As one of the relativistic electron tubes having compact configuration and high efficient output,the relativistic magnetron with direct axial radiation is very attractive in pulsed power and high power microwave fields for industrial and military applications.In this paper,the experimental investigation of a relativistic magnetron with axial TE 11 mode radiation is reported.Under a total length of ~ 0.3 m,volume of ~ 0.014 m 3,working at an applied voltage of 508 kV and a magnetic field of ~ 0.31 T,the relativistic magnetron radiates a microwave of 540 MW with the TE 11 mode at 2.35 GHz in the axial direction.The power conversion efficiency is 15.0%.After a lot of shots,the detected amplitudes of microwaves are nearly the same.The fluctuations of wave amplitudes are less than 0.3 dB. 相似文献
9.
Firstly, an X-band relativistic backward wave oscillator with a low guiding magnetic field is simulated, whose output microwave power is 520 MW. Then, an experiment is carried out on an accelerator to investigate a relativistic backward wave oscillator with a permanent magnetic field whose strength is 0.46 T. When the energy of the electron is 630 keV and the current of the electron beam is 6.7 kA, a 15 ns width pulsed microwave with 510 MW output power at 8.0 GHz microwave frequency is achieved. 相似文献
10.
S. B. Sazonov 《JETP Letters》2009,90(7):509-514
A method is proposed for the fast and deep polarization of a system of ground-state hyperfine sublevels of an atom having
an optical excited level or a system of excited-state sublevels. The method is based on the simultaneous action of pulsed
bichromatic resonance fields of optical and microwave ranges. The scheme of the ground-state sublevel polarization by bichromatic
or monochromatic microwave fields is also considered. 相似文献
11.
N. V. Ilyin M. A. Davydenko V. V. Khakhinov 《Radiophysics and Quantum Electronics》2007,50(5):352-359
We model theoretically the received spectrum in the case of sounding of the ionospheric HF radio channel by a chirp signal.
It is shown that the result of processing of an individual time sample of the received signal is equivalent to the sounding
of the radio channel by a complex narrow-band pulsed signal such that the group delays of its propagation modes determine
the maxima in the received spectrum. We analyze the quadrature components of realizations of the received signal at the intermediate
frequency at the bandpass-filter output in the receiving channel of the chirp ionosonde. The results of our analysis show
the possibility of reconstructing the transfer function of a HF radio channel in the sounding-frequency band for the delay
range determined by the characteristics of the intermediate-frequency bandpass filter. We propose a method for reconstructing
the transfer function of the ionospheric radio channel, which involves supplementing the circuit of primary processing of
the signal by a corrective digital filter with specified amplitude-frequency and phase-frequency characteristics. The proposed
method can be used for all operating regimes of the chirp ionosonde in the case of digital recording and processing of signals.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 5, pp. 387–395, May 2007. 相似文献
12.
The correlation of low-frequency sound signals from towed tonal low-frequency sources at the output of the scalar and vector channels is studied in shallow water. The correlation of the scalar field and signal received by a horizontally oriented vector receiver on average is 0.92–0.99; correlation with the signal received by a vertical vector receiver decreases to 0.66–85. When scalar fields or horizontal projections of the vibration velocity vector with application of the aperture synthesis algorithm are used, 3–5 normal waves are isolated; when the vertical component is used, 7–9 modes. It is demonstrated that the high signal correlation ensures direction-finding accuracy and suppression of strongly noise-emitting moving sources by 20–30 dB or more if the cardioid is directed at the source according to the zone of the minimum. 相似文献
13.
E. P. Gulin 《Acoustical Physics》2005,51(6):644-652
The frequency and time averaging of the fluctuations that occur in the cross-correlation function of a radiated noiselike acoustic signal with the signal received after its reflection from a rough water surface is considered. The variance and temporal correlation function are calculated for the output effect of a correlation receiver for different ratios between the averaging time and the time correlation interval of fluctuations, the band width of the radiated signal, and the frequency correlation interval of the transfer function fluctuations. 相似文献
14.
O. T. Loza D. K. Ul’yanov P. S. Strelkov I. E. Ivanov R. V. Baranov 《Bulletin of the Lebedev Physics Institute》2011,38(4):120-122
The operation of a pulse-periodic plasma relativistic microwave generator with a pulsed power of 50 MW was experimentally studied. A change in the shapes of the electron collector and output unit allowed a significant increase in the average emission power. The microwave pulse duration was increased from 30 to 70 ns, and the repetition rate of microwave pulses was increased from 5 to 50 Hz. 相似文献
15.
V. G. Andreev V. A. Vdovin K. V. Afanas’ev A. A. Eltchaninov A. I. Klimov 《Radiophysics and Quantum Electronics》2009,52(8):587-592
We present the results of testing a new thermoacoustic sensor designed to detect microwave pulses having durations from 3
to 120 ns at wavelengths of 0.8 and 3 cm. Operation of the sensor is based on the effect of generation of acoustic signals
during absorption of microwave pulses in a radiotransparent substrate–absorber–liquid layered structure . A thin nanometer-thick
film deposited on a substrate is used as an absorber. Microwaves are converted to an acoustic pulse in the film and the adjacent
liquid. The pulse is received by a wideband acoustic receiver and then recorded by a digital oscilloscope. It is shown that
for a pulse duration of 120 ns, the shape of the signal recorded by the thermoacoustic sensor completely corresponds to the
signal of a tube-diode detector of microwave pulses. The response of the thermoacoustic sensor to shorter pulses (3 and 5
ns long) is a pulse with a duration of 18 ns which is determined by a limited frequency band of the acoustic receiver. 相似文献
16.
Experimental investigation of a compact relativistic magnetron with axial TE11 mode radiation 下载免费PDF全文
As one of the relativistic electron tubes having compact configuration and high efficient output, the relativistic magnetron with direct axial radiation is very attractive in pulsed power and high power microwave fields for industrial and military applications. In this paper, the experimental investigation of a relativistic magnetron with axial TE11 mode radiation is reported. Under a total length of - 0.3 m, volume of - 0.014 m3, working at an applied voltage of 508 kV and a magnetic field of - 0.31 T, the relativistic magnetron radiates a microwave of 540 MW with the TE11 mode at 2.35 GHz in the axial direction. The power conversion efficiency is 15.0%. After a lot of shots, the detected amplitudes of microwaves are nearly the same. The fluctuations of wave amplitudes are less than 0.3 dB. 相似文献
17.
提出了一种基于纠缠见证的路径纠缠微波信号检测方法.路径纠缠微波是微波频段上的连续变量纠缠,介绍了利用微波压缩态和微波分束器制备路径纠缠微波的方法.根据部分转置正定判据以及2?2纠缠态密度矩阵的部分转置具有负本征值的性质,分别对常见的两种2?2纠缠进行了纠缠见证算符的构造,用于对两路信号是否为纠缠态进行判定.将连续变量纠缠的路径纠缠微波分解为大量2?2纠缠子系统叠加的纠缠态,证明其能够利用所构造的2?2纠缠见证算符来检测路径纠缠微波.同时分析了微波分束器的作用,并利用微波分束器设计了一种用于检测路径纠缠微波信号的实验方案,并在理论上分析了纠缠检测所得到的结果.结果表明,该方法能够有效检测路径纠缠微波信号,降低了检测的复杂度和计算量.本文的研究为纠缠微波的检测提供了思路. 相似文献
18.
In this paper, we study the influence of the frequency-dependent connection on the signal transmission in a system of two
interacting pulsed neural oscillators. The system is a model of two neurons with synaptic connection having the synaptic-plasticity
feature, i.e., synaptic-parameter variation as a function of the frequency characteristics of the signal. It is shown that
plastic connection can control the signal-transmission efficiency depending on the pulse-repetition rate and ensures stable
synchronization modes of the pulse trains with different ratios between the frequencies of the output and input pulses. Analytical
estimates for the parameter ranges corresponding to generation of the pulse response at the detector neuron depending on the
pulse-repetition rate at the oscillator neuron were obtained. 相似文献
19.
Fuhs M Prisner T Möbius K 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2001,149(1):67-73
Stochastic excitation with a full-width-half-maximum bandwidth of 250 MHz was used to perform Fourier-transform (FT) high-field/high-frequency electron paramagnetic resonance (EPR) at 3.4T/95 GHz (W-band). Thereby, the required microwave peak power is reduced by a factor of tau(p)/T1 as compared to equivalent pulsed FT EPR in which the spin system with spin-lattice relaxation time T1 is excited by a single microwave pulse of length tau(p). Stochastic EPR is particularly interesting under high-field/high-frequency conditions, because the limited output power of mm microwave sources, amplifiers, and mixers makes pulse FT EPR in that frequency domain impossible, at least for the near future. On the other hand, FT spectroscopy offers several advantages compared to field-swept magnetic resonance methods, as is demonstrated by its success in NMR and X-band EPR. In this paper we describe a novel stochastic W-band microwave bridge including a bimodal induction mode transmission resonator that serves for decoupling the microwave excitation and signal detection. We report first EPR measurements and discuss experimental difficulties as well as achieved sensitivity. Moreover, we discuss future improvements and the possibility for an application of stochastic W-band FT EPR to transient signals such as those of photoexcited radical pairs in photosynthetic reaction centers. 相似文献