A C-Band Monolithic GaAs PIN Diode SPST Switch

A monolithic single pole single throw （SPST） switch is developed with GaAs PIN diode technology from IMECAS. A novel small signal model of a GaAs PIN diode is developed for circuit simulation. The switch features an on-state insertion loss of less than 1.6dB and a return loss of greater than 10dB while maintaining an off-state isolation of greater than 23dB from 5.5 to 7. 5GHz. The measured 1dB power gain compression point is about 20dBm.

药用植物丹参的核型分析和C-banding研究

采用传统的核型分析技术，分析了栽培丹参有丝分裂中期染色体的核型和C—banding。结果表明：丹参中期染色体长度为1．30-2．39μm，核型公式是2n=16=4m＋2sm＋2st，其核型为2A型；单套染色体组显示出19条清晰稳定的C—bands，其中包括13条末端带，1条着丝粒带和5条中间带。

A Quality Assurance Procedure and Evaluation of Rainfall Estimates for C-Band Polarimetric Radar

A mobile C-band dual polarimetric weather radar J type （PCDJ）, which adopts simultaneous transmission and simultaneous reception （STSR） of horizontally and vertically polarized signals, was first developed in China in 2008. It was deployed in the radar observation plan in the South China Heavy Rainfall Experiment （SCHeREX） in the summer of 2008 and 2009, as well as in Tropical Western Pacific Ocean Observation Experiments and Research on the Predictability of High Impact Weather Events from 2008 to 2010 in China （TWPOR）. Using the observation data collected in these experiments, the radar systematic error and its sources were analyzed in depth. Meanwhile an algorithm that can smooth differential propagation phase （~Dp） for estimating the high-resolution specific differential phase （KDP） was developed. After attenuation correction of reflectivity in horizontal polarization （ZH） and differential reflectivity （ZDR） of PCDJ radar by means of KDP, the data quality was improved significantly. Using quality-controlled radar data, quantitative rainfall estimation was performed, and the resutls were compared with rain-gauge measurements. A synthetic ZH /KDp-based method was analyzed. The results the traditional ZH-based method when the rain suggest that the synthetic method has the advantage over rate is 〉5 mm h^-1. The more intensive the rain rates, the higher accuracy of the estimation.

Physical design and cooling test of C-band standing wave accelerating tube

The physical design and cooling test of a C-band 2MeV standing wave （SW） accelerating tube are described in this paper. The designed accelerating structure consists of 3-cell buncher and 4-cell accelerating section with a total length of about 163mm, excited with 1MW magnetron. Dynamic simulation presents that about 150mA beam pulse current and 30% capture efficiency can be achieved. By means of nonlinear Gauss fit on electron transverse distribution, the diameter of beam spot FWHM （full width at half maximum of density distribution） is about 0.55mm. Cooling test results of the accelerating tube show that frequencies of cavities are tuned to 5527MHz and the field distribution of bunching section is about 3：9：10.

Raindrop Size Distribution Parameters Retrieved from Xinfeng C-Band Polarimetric Radar Observations

The objective of this research was to acquire a raindrop size distribution(DSDs)retrieved from C-band polarimetric radar observations scheme for the first time in south China.An observation period of the precipitation process was selected,and the shape-slope(μ-Λ)relationship of this region was statistically analyzed using the raindrop sample observations from the two-dimensional video disdrometer(2DVD)at Xinfeng Station,Guangdong Province.Simulated data of the C-band polarimetric radar reflectivity ZHHand differential reflectivity ZDRwere obtained through scattering simulation.The simulation data were combined with DSD fitting to determine the ZDR-Λand log10(ZHH/N0)-Λrelationships.Using Xinfeng C-band polarimetric radar observations ZDRand ZHH,the raindrop Gamma size distribution parametersμ,Λ,and N0were retrieved.A scheme for using C-band polarimetric radar to retrieve the DSDs was developed.This research revealed that during precipitation process,the DSDs obtained using the C-band polarimetric radar retrieval scheme are similar to the 2DVD observations,the precipitation characteristics of rainfall intensity(R),mass-weighted mean diameter(Dm)and intercept parameter(Nw)with time obtained by radar retrieval are basically consistent with the observational results of the 2DVD.This scheme establishes the relationship between the observations of the C-band polarimetric radar and the physical quantities of the numerical model.This method not only can test the prediction of the model data assimilation system on the convective scale and determine error sources,but also can improve the microphysical precipitation processes analysis and radar quantitative precipitation estimation.The present research will facilitate radar data assimilation in the future.

High Gain UWB Four Elements Antenna Array for C-Band and X-Band Application

The C-band is allocated for commercial telecommunications via satellites. Amateur satellite operations in the frequency range 5.830 to 5.850 GHz for down-links and 5.650 to 5.670 GHz for up-links are allowed by International Telecommunication Union. The X-band is used for terrestrial broadband communication, radar applications, and portions of the X-band are assigned for deep space telecommunications. In this paper, a design of 4 × 1 Ultra Wide Band (UWB) antenna array for C-band and X-band applications is introduced. Metamaterial sixteen-unit cells are incorporated into each antenna element for radiation characteristics enhancement purposes. Permeability and permittivity of metamaterial unit cells are obtained all over the operating bandwidth. UWB unequal power divider is used to feed the proposed four elements antenna array based on Chebyshev excitation method. The proposed antenna has a suitable 3 dB beam width and gains all over the operating bandwidth which extends from 5.6 GHz to 10.9 GHz. The proposed antenna covers 60% and 72.5% of the C-band and X-band, respectively. The proposed antenna is fabricated, measured, and good agreement is obtained between simulated and measured results. The obtained performance ensures the suitability of the proposed antenna array for C-band and X-band applications.

5G发信干扰卫星下行(C-Band)研究

本文主要介绍了5G基站部署后(以电信3.4-3.5 GHz为例)对附近的卫星地球站下行接收(C-Band,3.625-4.2 GHz)干扰的现象、原理及解决手段,对将来5G业务和卫星业务(C-Band)和平共存提出一些建议。

Design of MEMS C-Band Microstrip Antenna Array Based on High-Resistance Silicon for Intelligent Ammunition

In recent years, microstrip antennas have been more widely applied in satellite communications, mobile phones, unmanned aerial vehicle （UAV）, and weapons. A micro-electro-mechanical systems-based （MEMS-based） high-resistance silicon C-band microstrip antenna array has been designed for the intelligent ammunition. The center frequency is 4.5 GHz. A cavity has been designed in substrate to reduce the dielectric constant of silicon and high-resistance silicon has been used as the material of substrate to improve the gain of antenna. It is very easy to be manufactured by using MEMS technology because of the improved structure of the antenna. The results show that the gain of the antenna is 8 dB and voltage standing wave ratio （VSWR） is less than 2 by the analysis and simulation in high freauencv structure simulator （HFSS）.

An Antenna Like Form “Hand” of the Man on Five Bands Wlan/Wimax/Hiper LAN2/C-Band Applications

In this paper, a new form of printed antenna for a five-band C-band applications is presented. The proposed antenna consists of six simple rectangles, whose geometry resembles all the “hand” of man. By varying the geometries and dimensions of these six rectangles, five different resonance modes can be effectively created for five distinct frequency bands, respectively. The overall dimension of the proposed antenna can reach 45 × 50 × 2.54 mm3. The simulated results show that the presented antenna is adapted to 4.6/5.24/5.6/6.7/7.3 GHz five bands which are applied to C-band.

Exploitation of Electromagnetic Models for Sea Wind Speed Estimation from C-Band Sentinel-1 Images

Among the different available wind sources, i.e. in situ measurements, numeric weather models, the retrieval of wind speed from Synthetic Aperture Radar (SAR) data is one of the most widely used methods, since it can give high wind resolution cells. For this purpose, one can find two principal approaches: via electromagnetic (EM) models and empirical (EP) models. In both approaches, the Geophysical Model Functions (GMFs) are used to describe the relation of radar scattering, wind speed, and the geometry of observations. By knowing radar scattering and geometric parameters, it is possible to invert the GMFs to retrieve wind speed. It is very interesting to compare wind speed estimated by the EM models, general descriptions of radar scattering from sea surface, to the one estimated by the EP models, specific descriptions for the inverse problem. Based on the comparisons, some ideas are proposed to improve the performance of the EM models for wind speed retrieval.

Design and study of a C-band pulse compressor for the SXFEL linac

A C-band RF pulse compressor is in development at SINAP It comprises of two resonant cavities,two mode convertors and a 3 dB power divider.TE_(0.1.15)mode is selected for obtaining higher quality factor Q_0 of the RF pulse compressor cavities,so that the power gain factor can be 3.2,which is supposed to multiply the RF power from 50 MW to 1 60 MW.In this paper,we report our work on C-band RF pulse compressor,namely the design simulation and cold test results.

Three Dimensional PIC Simulation of a C-Band Relativistic Magnetron

The dispersion relation of a conventional 6-vane relativistic magnetron is derived and numerically calculated, which is employed to analyze the operating frequency of the device.Initial results of three-dimensional particle-in-cell simulation show that an average output microwave power of about 0.96GW at 4.5GHz is obtained at the beam energy of 437keV and current of 12.2kA when the externally applied magnetic field is about 0.6T.The efficiency is about 18%. An average output power of microwave about 4.4GW at 4.37GHz is also obtained at the beam energy of 1.05MeV and the current of 20.TkA when the structure parameters are improved.The efficiency is about 20%.

Theoretical and experimental researches on C-band three-cavity transit-time effect oscillator

The C-band three-cavity transit-time effect oscillator (3C TTTO) is a novel high power microwave device based on the transit-time effect of the three-cavity (3C) resonator. The operational principle of this device is briefly expounded in this paper, and the theoretical and experimental researches on the radial insulation diode, the 3C resonator, the double-gap output cavity and the circular waveguide bevel cut radiation antenna are presented in detail. By using the analytic method, the eigen modes and their field distributions of the 3C resonator are developed, and some basic laws of the transit-time effect are obtained in non-π mode field of the 3C resonator. At last, the experimental results are given. This device generated RF peak power in excess of 400MW with 15ns FWHM, and its beam-wave power conversion efficiency is about 17%.

Mode-locked fiber laser in the C-band region for dual-wavelength ultrashort pulses emission using a carbon nanotube saturable absorber

A saturable absorber is commonly employed to generate an ultrashort laser with a mode-locking scheme. In an erbium-doped fiber laser system, the laser regimes of either 1530 or 1550 nm wavelength are procured based on the absorption profile of the erbium-doped fiber. The absorption of the erbium-doped fiber is designed to emit at both wavelengths by controlling the net gain of the laser cavity. Subsequently, simultaneous erbium-doped fiber laser emission is attained at 1533.5 and 1555.1 nm with the pulse duration of 910 and 850 fs, respectively.Therefore, this work maximizes the output portfolios of a mode-locking fiber laser for dual-wavelength ultrashort pulses emission.

New linear accelerator (Linac) design based on C-band accelerating structures for SXFEL facility

A C-band accelerator structure is one promising technique for a compact XFEL facility. It is also attractive in beam dynamics in maintaining a high quality electron beam, which is an important factor in the performance of a free electron laser. In this paper, a comparison between traditional S-band and C-band accelerating structures is made based on the linac configuration of a Shanghai Soft X-ray Free Electron Laser （SXFEL） facility. Throughout the comprehensive simulation, we conclude that the C-band structure is much more competitive.

Conceptual study and design of A C-band photocathode injector

Purpose A C-band photocathode injector composed of a 3.6-cell C-band photocathode RF gun and two 1.8-m C-band accelerating structures is proposed.The injector is a low emittance electron source for free electron lasers(FEL)and other compact light sources.Methods The RF structure of the cavities is designed with 2D SUPERFISH simulation.The beam dynamic study in ASTRA helps rectify the 2D RF simulation.To feed the cavities,a design of extracoaxial coupler with RF gun structure is presented.Results With compact focusing solenoids,for 0.25 nC bunch charge,the final energy can reach 6.9 MeV energy and the 95%emittance can be as low as 0.23 mm mrad(95%).Conclusion All the details of RF design and beam dynamics studies are presented in this paper,and the design satisfied the requirements of FEL and other applications.

RF study of a C-band barrel open cavity pulse compressor

This paper focuses on the RF study of a C-band barrel open cavity （BOC） pulse compressor. The operating principle of BOC is presented and the technical specifications are determined. The main parts of BOC such as the cavity, the matching waveguide, the coupling slots and the tuning rings were numerically sinmlated by 3-D codes software HFSS and CST Microwave Studio （MWS）. The ＂whispering gallery＂ mode TM6,1,1 with an unload Q of 100000 was chosen to oscillate in the cavity. An energy multiplication factor of 1.99 and a peak power gain of 6.34 was achieved theoretically.

Design of a high-efficiency C-band backward wave oscillator

For practicability of the high power microwave source,a C-band backward wave oscillator（BWO） which has high conversion efficiency is designed.When the axial guiding magnetic field is 0.83 T,the electron energy and the beam current of the diode are respectively 80 keV and 2.1 kA,a microwave output power of 100 MW at 7.4 GHz microwave frequency with 65% conversion efficiency is achieved in simulation.

Design of a C-band relativistic extended interaction klystron with coaxial output cavity

In order to overcome the disadvantages of conventional high frequency relativistic klystron amplifiers in power capability and RF conversion efficiency, a C-band relativistic extended interaction klystron amplifier with coaxial output cavity is designed with the aid of PIC code MAGIC. In the device, disk-loaded cavities are introduced in the input and intermediate cavity to increase the beam modulation depth, and a coaxial disk-loaded cavity is employed in the output cavity to enhance the RF conversion efficiency. In PIC simulation, when the beam voltage is680 k V and current is 4 k A, the device can generate 1.11 GW output power at 5.64 GHz with an efficiency of 40.8%.

Design,fabrication,and cold-test results of C-band spherical RF pulse compressor prototype

Purpose Pulse compressor is a useful and common RF structure for Free Electron Laser and Linear Collider Facilities, whichcan improve the input power of accelerating structures significantly.Methods In this study, we designed, fabricated and tested a prototype of a compact C-band spherical pulse compressor.This pulse compressor utilizes one high Q0 spherical RF resonant cavity that works with two degenerated TE1,1,3modes anda dual-mode polarized coupler. The cavity and coupler were designed and machined separately and then brazed together.The prototype was tested carefully using vector network analyzer, and a cold-test system was set up to check the workingconditions of the spherical pulse compressor with inversed input powerResults Associated with the C-band high-gradient accelerating structures, the peak power gain and energy multiply factorcan be as high as 6.1 and 1.85, respectively, in theory. The average power gain is 3.8 in the first 0.372 μs after the phasereverse, which is the accelerator filling time. During the cold test, a peak power multiply factor of 6.04 and an energy multiplyfactor of 1.83 were achieved.Conclusions The test results agreed with the design well. The prototype was successfully made as a pre-research for thefuture energy multiplying scheme of SXFEL.