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1.
Xiaoqiang Xie Ruiming Xu Bo Yan Yong Zhang Weigan Lin 《International Journal of Infrared and Millimeter Waves》2005,26(10):1453-1464
This paper presents the analysis and design of a novel millimeter-wave power combining circuit. This combing circuit is composed
of a new style 3-dB combiner, which achieves low-loss, wide-band, and symmetric power division. Different from conventional
Wilkinson hybrid, the proposed combiner requires no isolating resistor, and is easier fabricated and more suitable for millimeter
integrate circuits. Analytical and experimental work on a two-way combining circuit with wave-guide ports in Ka-band shows
the combiner has an insertion loss of 0.2dB, and a power-combining efficiency above 80% in 32–33GHz is obtained. 相似文献
2.
为了实现大功率容量和高效率的空间功率合成,将基于波导腔体的二维Meniscus透镜用于毫米波功率合成器的设计.对透镜中传输的主模(TE10波)的散射效应进行了分析,并且设计了匹配层减小透镜结构带来的反射.在30 GHz频率上利用Rexolite介质的Meniscus透镜设计出了10路功率合成器,对不同结构的功率合成器和不同参数的透镜进行了研究,得到了最终的优化结果.CST-MMW的仿真结果表明该功率合成器在30 GHz合成效率可以达到92.6%,并且其80%以上效率工作带宽可以覆盖整个Ka波段. 相似文献
3.
Michael Höft Jochen Weinzierl Rolf Judaschke 《International Journal of Infrared and Millimeter Waves》2002,23(7):1127-1146
Holography is a promising technique for power combining applications in the frequency range of short millimeter and submillimeter waves. In this paper, quasi-optical holographic power combining circuits are investigated. An equivalent network is utilized which rigorously models horn arrays and biperiodic dielectric structures in order to design computer-generated holograms. We apply the network model to a 5-element quasi-optical power combiner and demonstrate its capability. The hologram is designed for 150 GHz and has an efficiency of 92.5 % with a 90 % bandwidth of 5.3 %. With the aid of a broadband waveguide power divider and a vector field measurement system, the circuit is analyzed. 相似文献
4.
H. C. Liang H. L. Chang W. C. Huang K. W. Su Y. F. Chen Y. T. Chen 《Applied physics. B, Lasers and optics》2009,97(2):451-455
The large third-order nonlinearity of GdVO4 crystals is employed to realize the compact efficient continuous-wave self-mode locking in the range of several GHz in a
Nd:GdVO4 laser with a simple linear cavity without the need of any additional components. With a pump power of 2.5 W, the compact
laser cavity produces average output powers greater than 0.7 W with a pulse width as short as 23 ps in the range of 2–6 GHz. 相似文献
5.
A master oscillator power amplifier (MOPA) system in which the output from an end-pumped Nd:YAG oscillator cavity dumped at
500 kHz is scaled up by a four-stage Nd:YVO4 amplifier is reported. Decrease in extraction efficiency of the amplifier chain with crystals different from that in the
oscillator was analyzed. With the 5.4 W seed output, 118 W of power was extracted from the amplifier chain at the pump power
of 345 W, with an extraction efficiency of 34.2% and an overall optical–optical efficiency of 30.9% for the MOPA system. The
beam quality factors were measured as M
x
2=1.45 and M
y
2=1.59 in two orthogonal directions, respectively. 相似文献
6.
7.
为了抑制偏振态漂移带来的功率变化给传输稳定度造成的影响,设计了一种能够快速补偿偏振变化的频率传输系统。该系统将锁模光作为光源,结合PID控制器反馈调节的原理,利用光功率放大器(EDFA)、起偏器、可变光功率衰减器(VOA)和单片机实现。实验结果表明:该系统能够有效抑制偏振态随着环境改变而发生的漂移,经过10 km传输之后的输出光功率稳定度达到110-5,与自由漂相比提高了200倍。将整个系统应用在光梳频率传输系统中,可以提高系统的鉴相精度,在5 GHz的传输频率上,可以有效消除偏振态变化引入的~50 fs的相位抖动。 相似文献
8.
为了实现大功率容量和高效率的空间功率合成,将基于波导腔体的二维Meniscus透镜用于毫米波功率合成器的设计.对透镜中传输的主模(TE10波)的散射效应进行了分析,并且设计了匹配层减小透镜结构带来的反射.在30GHz频率上利用Rexolite介质的Meniscus透镜设计出了10路功率合成器,对不同结构的功率合成器和不同参数的透镜进行了研究,得到了最终的优化结果.CST-MMW的仿真结果表明该功率合成器在30GHz合成效率可以达到92.6%,并且其80%以上效率工作带宽可以覆盖整个Ka波段. 相似文献
9.
Kaijun Song Yong Fan Yonghong Zhang 《International Journal of Infrared and Millimeter Waves》2007,28(6):473-478
A low-profile millimeter-wave substrate integrated waveguide (SIW) power divider/combiner is presented in this paper. The
simplified model of this compact SIW power dividing/combining structure has been developed. Analysis based on equivalent circuits
gives the design formula for perfect power dividing/combining. In order to verify the validity of the design method, a four-way
SIW power divider/combiner circuit operating at Ka band is designed, fabricated and measured. Good agreement between simulated
and measured results is found for the proposed passive power divider/combiner. Experiments on the four-way passive divider/combiner
back-to-back design demonstrate a minimum overall insertion loss of 1.5 dB at 31.1 GHz, corresponding to a power-combining
efficiency of 84%. The measured 10-dB return loss bandwidth is demonstrated to be 2.2 GHz, and its 0.5-dB bandwidth was 2 GHz. 相似文献
10.
High power passive Q-switching was achieved with a pulse width of 18–32 ns by using a diode-side-pumped Nd:Gd0.6Y0.4VO4 bounce amplifier. An average output power of > 8 W was obtained at a pump power of 39 W. The peak power of the Q-switched
output was adjusted within 1.9–5.2 kW by changing the Nd concentration. The mixed vanadates showed significantly higher Q-switching
performances in comparison with pure Nd:GdVO4.
PACS 42.55.Xi; 42.60.Gd; 42.60.Da 相似文献
11.
基于0.13 m SiGe BiCMOS工艺, 研究和设计了一种D波段功率放大器芯片。该放大器芯片用了四个功率放大器单元和两个T型结网络构成。功率放大器单元采用了三级的cascode电路结构。低损耗的片上T型结网络既能起到片上功率合成/分配的功能, 又能对输入输出进行阻抗匹配。对电路结构进行了设计、流片验证和测试。采用微组装工艺将该芯片封装成为波导模块。小信号测试结果表明:该功放芯片工作频率为125~150 GHz, 最高增益在131 GHz为21 dB, 最低增益在150 GHz为17 dB, 通带内S22小于-7 dB, S11小于-10 dB。大信号测试结果表明:该功放模块在128~146 GHz带内输出功率都大于13 dBm, 在139 GHz时, 具有最高输出功率为13.6 dBm, 且1 dB压缩功率为12.9 dBm。 相似文献
12.
13.
Terahertz/Millimeter Wave Characterizations of Soils for Mine Detection: Transmission and Scattering
Todd W. Du Bosq Robert E. Peale Glenn D. Boreman 《International Journal of Infrared and Millimeter Waves》2008,29(8):769-781
The detection of anti-personnel mines depends on the soil transmission and scattering at a given wavelength. Transmission
spectra were measured over the range 90–4200 GHz for 19 soil samples that span a number of soil orders that have extensive
worldwide distribution using a vector network analyzer (90–140 GHz) and a Fourier spectrometer (120–4200 GHz). Transmission
drops to nearly zero for wavelengths shorter than the characteristic particle size of the sample as a consequence of scattering.
This interpretation is supported by a fit to a standard scattering model with physically reasonable fitting parameters. Transmission
spectra were also measured for various liquids (90–600 GHz) for possible index matching. These liquids were mixed with the
soil sample and were found to reduce scattering and increase transmission through the soil at higher frequencies. This work
is relevant to mine detection using terahertz and millimeter wave radiation for high resolution images through the soil. 相似文献
14.
Zisis C. Ioannidis Olgierd Dumbrajs Ioannis G. Tigelis 《International Journal of Infrared and Millimeter Waves》2008,29(4):416-423
We consider two continuous frequency tunable CW coaxial gyrotron oscillators, one 330 GHz with 3 GHz bandwidth and output
power 50 – 400 W for scientific applications and one 30 GHz with 0.4 GHz bandwidth and output power 40 – 140 kW for industrial
applications. The continuous tuning of both gyrotrons is achieved by moving the linearly tapered inner conductor in the axial
direction in combination with the proper adjustment of the operating magnetic field. We consider also a non-linear tapering,
which makes it possible to reduce the length of the insert and to improve efficiency of the device. 相似文献
15.
Lei Zhang Huawei Jiang Shuzhen Cui Jinmeng Hu Yan Feng 《Laser \u0026amp; Photonics Reviews》2014,8(6):889-895
Robust high‐power narrow‐linewidth lasers at 589 nm are required for sodium laser guide star adaptive optics in astronomy. A high‐power 589 nm laser based on Raman fiber amplifier is reported here, which works in both continuous‐wave and pulsed formats. In the continuous‐wave case, the laser produces more than 50 W output. In the pulsed case, the same laser produces square‐shaped pulses with tunable repetition rate (500 Hz to 10 kHz) and duration (1 ms to 30 μs). The peak power is as high as 84 W and remains constant during the tuning. The laser also emits an adjustable sideband at 1.71 GHz away from the main laser frequency for better sodium excitation. The versatility of the laser offers much flexibility in laser guide star application. 相似文献
16.
We have developed and tested a gyroklystron operating with the second harmonic of the electron cyclotron frequency at a frequency
of 32.3 GHz in the field of a permanent magnet. In the two-and three-cavity versions of the gyroklystron, the peak power of
the output radiation reached 320 kW with an efficiency of 30%, an amplification coefficient of 20–25 dB, and an operating
frequency bandwidth of 0.05%. In the wide-band version of the gyroklystron, the amplification bandwidth was equal to 0.27%
for an output power of 200 kW and an amplification coefficient of 13 dB. 相似文献
17.
C. Y. Li Q. J. Peng B. S. Wang Y. Bo D. F. Cui Z. Y. Xu X. Q. Feng Y. B. Pan 《Applied physics. B, Lasers and optics》2011,103(2):285-289
We demonstrate for the first time a diode-side-pumped quasi-continuous-wave (QCW) operation of a 1123 nm Nd:YAG ceramic laser.
The single 1123 nm wavelength is acquired through precise coating. With a pump power of 1000 W, an output power of 247 W is
obtained, corresponding to an optical–optical conversion efficiency of 24.7%. At the maximal output power, the pulse repetition
rate and pulse width are measured to be 1.1 kHz and 180 μs, respectively. The numerical simulations for wavelength selectivity
from 1112, 1116 and 1123 nm are discussed in detail. 相似文献
18.
Dai Lu David Rutledge Milan Kovacevic Jon Hacker 《International Journal of Infrared and Millimeter Waves》2002,23(5):693-704
This paper presents an active patch array designed at 24 GHz. It can be used as a front-end component for a phased array. A series resonant array structure is chosen which is compact and easy excite. With 5 elements, the array proved a 12-dB antenna gain. A power amplifier and a low noise amplifier are designed on a single GaAs chip (PALNA). Bias switch is used in the PALNA, which greatly reduces the switch loss in a transceiver and increases the efficiency. 20-dB small signal gain is achieved in both power amplifier and low noise amplifier. The active patch array is built by the combination of the patch array and PALNA. The measured active gain of this antenna is 35-dB for the PA mode and 31-dB for the LNA mode. This active patch array can obtain an EIRP of 34 dBm with a total radiated power of 22dBm and a maximum PAE of 32%. To check the noise performance, we applied sources at both normal temperature and 77K (liquid nitrogen) and extracted the noise figure (3.5 dB) of the active antenna by the Y factor method. The results proved that the active antenna is working efficiently as both a transmitting and receiving antenna. 相似文献
19.
Coherent terahertz radiation in a widely step-tunable range of 72.3–2706 μm (0.11–4.15 THz) has been generated in GaAs crystal
by difference-frequency generation using one CO2 laser with dual-wavelength output. The peak power of THz pulse reaches 35 W at the wavelength of 236.3 μm, which corresponds
to a pulse energy of 2.1 μJ. An average power of 10 μW has been achieved when working repetitively. This efficient terahertz
radiation source is more compact and widely tunable than other THz sources pumped by CO2 laser. 相似文献
20.
L. Bouzaïene L. Sfaxi M. Baira H. Maaref C. Bru-Chevallier 《Journal of nanoparticle research》2011,13(1):257-262
Self-assembled InAs/GaAs (001) quantum dots (QDs) were grown by molecular beam epitaxy using ultra low-growth rate. A typical
dot diameter of around 28 ± 2 nm and a typical height of 5 ± 1 nm are observed based on atomic force microscopy image. The
photoluminescence (PL) spectra, their power and temperature dependences have been studied for ground (GS) and three excited
states (1–3ES) in InAs QDs. By changing the excitation power density, we can significantly influence the distribution of excitons
within the QD ensemble. The PL peak energy positions of GS and ES emissions bands depend on an excitation light power. With
increasing excitation power, the GS emission energy was red-shifted, while the 1–3ES emission energies were blue-shifted.
It is found that the full width at half maximum of the PL spectra has unusual relationship with increasing temperature from
9 to 300 K. The temperature dependence of QD PL spectra shown the existence of two stages of PL thermal quenching and two
distinct activation energies corresponding to the temperature ranges I (9–100 K) and II (100–300 K). 相似文献