A Novel Design of Antenna Array with Two K-Band Circularly Polarized Antenna

As an important part of phased array system,the research on phased array antenna is very necessary.The phased array antenna achieves the scanning beam adaptively by regulating the phase difference between each array element.In this paper,a dual K-band circularly polarized antenna with high broadband,broadband beam,wide axial ratio bandwidth and high radiation efficiency is designed.We combine with the advantages of slot antenna and aperture antenna,use multimode waveguide cavity structure to design an aperture antenna,which is fed to waveguide circular polarizer by slot coupling in order to realize circular polarization radiation.Meanwhile,it has the characteristics of broadband,broadband beam,wide axial ratio bandwidth and high radiation efficiency.A slit antenna is designed by using a multimode waveguide cavity structure and a slit coupling feed to a waveguide circular polarizer is used to achieve circularly polarized radiation.The designed antenna consists of two K-band circularly polarized antenna units,and the spacing between the two units is 9.5 mm,which is fed by aK-band T/R module(Transmitter/Receiver module).In order to study the performance of the pattern in the case of the research group,the 2-unit structure is established.The simulation results of frequency–axial ratio bandwidth are given,and the simulation result of the antenna array is shown.The practical results of antenna design and test are also given.

Design of Ka-Band Phased Array Antenna with Calibration Function

In this paper,we have proposed a novel structure of Ka-band based phased array antenna with calibration function.In the design of Kaband antenna,the active phased array system is adopted and the antenna would work in the dual polarization separation mode.We have given out the schematic diagram for the proposed Ka-band antenna,where the Kaband antenna is in the form of waveguide slot array antenna,with 96 units in azimuth and 1 unit in distance.Each group of units is driven by a singlechannel Transmitter/Receiver(T/R)component,and the whole array contains 192 T/R components in total.The size of the T/R component is 55mm(length)×50mm(width)×5.8mm(height),3 Sub-micro Sub-Miniature Push-on(SSMP)blind sockets and a 21-core low-frequency socket are designed on the two sides of the T/R component.In order to meet the technical specifications of phased array antenna,the Ka-band transceiver component is designed based on Low Temperatrue Co-fired Ceramic(LTCC)technology to achieve miniaturization and lightweight.In our approach,the feed network includes two parts:transceiver network and calibration network.The transceiver network consists of 241:8 time-delay power dividers,12 two-way power dividers and 2 six-way time-delay power dividers.The power supply required by theKaband antenna unit is provided to each active component by the power module after Ka band wavelet control distribution.Simulation and measurement results are given in the form of standing wave and scanning capability.

A Compact Ka-Band PHEMT MMIC Voltage Controlled Oscillator

A compact Ka-band monolithic microwave integrated circuit(MMIC) voltage controlled oscillator (VCO) with wide tuning range and high output power,which is based on GaAs PHEMT process,is presented.A method is introduced to reduce the chip size and to increase the bandwidth of operation.The procedure to design a MMIC VCO is also described here.The measured oscillating frequency of the MMIC VCO is 36±1.2GHz and the output power is 10±1dBm.The fabricated MMIC chip size is 1.3mm×1.0mm.

A Ka-Band PHEMT MMIC 1W Power Amplifier

The performance of a microwave monolithic integrated circuit .（MMIC） amplifier with high output power in the Ka-band is presented. Using 75mm 0.25μm GaAs PHEMT technology provided by the Hebei Semiconductor Research Institute, this three-stage power amplifier, with a chip size of 19.25mm^2 （3.5mm × 5.5mm）, on 100μm GaAs substrate achieves a linear gain of more than 16dB in the 32.5-35.5GHz frequency range,with an average output power at 1dB gain compression of P1dB = 29. 8dBm and a maximum saturated output power of Psat = 31dBm.

Study of the ability of SWOT to detect sea surface height changes caused by internal solitary waves

Surface Water and Ocean Topography(SWOT)is a next-generation radar altimeter that offers high resolution,wide swath,imaging capabilities.It has provided free public data worldwide since December 2023.This paper aims to preliminarily analyze the detection capabilities of the Ka-band radar interferometer(KaRIn)and Nadir altimeter(NALT),which are carried out by SWOT for internal solitary waves(ISWs),and to gather other remote sensing images to validate SWOT observations.KaRIn effectively detects ISW surface features and generates surface height variation maps reflecting the modulations induced by ISWs.However,its swath width does not completely cover the entire wave packet,and the resolution of L2/L3 level products(about 2 km)cannot be used to identify ISWs with smaller wavelengths.Additionally,significant wave height(SWH)images exhibit blocky structures that are not suitable for ISW studies;sea surface height anomaly(SSHA)images display systematic leftright banding.We optimize this imbalance using detrending methods;however,more precise treatment should commence with L1-level data.Quantitative analysis based on L3-level SSHA data indicates that the average SSHA variation induced by ISWs ranges from 10 cm to 20 cm.NALTs disturbed by ISWs record unusually elevated SWH and SSHA values,rendering the data unsuitable for analysis and necessitating targeted corrections in future retracking algorithms.For the normalized radar cross section,Ku-band and four-parameter maximum likelihood estimation retracking demonstrated greater sensitivity to minor changes in the sea surface,making them more suitable for ISW detection.In conclusion,SWOT demonstrates outstanding capabilities in ISW detection,significantly advancing research on the modulation of the sea surface by ISWs and remote sensing imaging mechanisms.

Performance Analysis and Simulation of Higher Order Modulations for Ka-Band Fixed Satellite Communication

The performance analysis and simulation of spectrally efficient modulation schemes , MPSK and MQAM, for Ka-band fixed satellite communication system are provided. The effects of bandwidth limitation, nonlinearityity distortion and adjacent channel interference (ACI) in Ka-band satellite channel corrupted by additive white Gaussian noise (AWGN) are taken into account. The analytical expressions of the HER of coherent MPSK and MQAM signal are obtained and shown to be in good agreement with the simulation results.

A Ka-band Solid-state Transmitter Cloud Radar and Data Merging Algorithm for Its Measurements

This study concerns a Ka-band solid-state transmitter cloud radar, made in China, which can operate in three different work modes, with different pulse widths, and coherent and incoherent integration numbers, to meet the requirements for cloud remote sensing over the Tibetan Plateau. Specifically, the design of the three operational modes of the radar（i.e., boundary mode M1, cirrus mode M2, and precipitation mode M3） is introduced. Also, a cloud radar data merging algorithm for the three modes is proposed. Using one month＇s continuous measurements during summertime at Naqu on the Tibetan Plateau,we analyzed the consistency between the cloud radar measurements of the three modes. The number of occurrences of radar detections of hydrometeors and the percentage contributions of the different modes＇ data to the merged data were estimated.The performance of the merging algorithm was evaluated. The results indicated that the minimum detectable reflectivity for each mode was consistent with theoretical results. Merged data provided measurements with a minimum reflectivity of -35 dBZ at the height of 5 km, and obtained information above the height of 0.2 km. Measurements of radial velocity by the three operational modes agreed very well, and systematic errors in measurements of reflectivity were less than 2 dB. However,large discrepancies existed in the measurements of the linear depolarization ratio taken from the different operational modes.The percentage of radar detections of hydrometeors in mid- and high-level clouds increased by 60% through application of pulse compression techniques. In conclusion, the merged data are appropriate for cloud and precipitation studies over the Tibetan Plateau.

Microphysical characteristics of precipitating cumulus cloud based on airborne Ka-band cloud radar and droplet measurements

Based on cloud-probe data and airborne Ka-band cloud radar data collected in Baoding on 5 August 2018,the microphysical structural characteristics of cumulus(Cu)cloud at the precipitation stage were investigated.The cloud droplets in the Cu cloud were found to be significantly larger than those in stratiform(STF)cloud.In the Cu cloud,most cloud particles were between 7 and 10μm in diameter,while in the STF cloud the majority of cloud particles grew no larger than 2μm.The sensitivity of cloud properties to aerosols varied with height.The cloud droplet effective radius showed a negative relationship with the aerosol number concentration(Na)in the cloud planetary boundary layer(PBL)and upper layer above the PBL.However,the cloud droplet concentration(Nc)varied little with decreased Na in the high liquid water content region above 1500 m.High Na values of between 300 and 1853 cm-3 were found in the PBL,and the maximum Na was sampled near the surface in August in the Hebei region,which was lower than that in autumn and winter.High radar reflectivity corresponded to large FCDP(fast cloud droplet probe)particle concentrations and small aerosol particle concentrations,and vice versa for low radar reflectivity.Strong updrafts in the Cu cloud increased the peak radius and Nc,and broadened cloud droplet spectrum;lower air temperature was favorable for particle condensational growth and produced larger droplets.

AN ADAPTIVE FEC SCHEME FOR Ka-BAND SATELLITE COMMUNICATIONS

Rain attenuation is the major problem for Ka-band satellite communications, and the fading due to rain can be well described by a lognormally distributed, first-order auto regressive model. Forward Error-control Coding (FEC) techniques can be used to reduce the effect of the rain attenuation, but the use of FEC causes a reduction in the bandwidth efficiency.In order to increase the bandwidth efficiency as well as maintain high link availability, an Adaptive Forward Error-control Coding (AFEC) scheme with rain fading prediction is proposed and analyzed in this paper. The results show that AFEC offers a good trade-off between link availability and bandwidth efficiency.

精密星间微波测距系统观测数据模拟与预处理技术

星间精密微波测距系统是GRACE卫星最核心的有效载荷之一,系统仿真模拟技术的预研是GRACE计划跟踪研究不可或缺的环节。通过对测距系统基频相位观测值的模拟,单频双程星间相位观测值模型、单频双程星间距离观测值模型及双频双程星间距离值模型的建立,实现了由星上原始相位数据到星间有偏距离观测值的转换,给出了基频相位观测值的模拟结果及预处理结果。

A Satellite Communication System Transmission Scheme Based on Probabilistic Shaping

In this paper, A transmission scheme based on probabilistic shaping applied to satellite communication systems is proposed. 16QAM is taken as an example to establish a 1GBaud ROF experimental system working in Ka-band. The experiment results show that the PS-16QAM signal has better performance in terms of bit error rate than the uniform 16QAM, and its performance is close to the uniform 8QAM scheme.

Macro-and Micro-physical Characteristics of Different Parts of Mixed Convective-stratiform Clouds and Differences in Their Responses to Seeding

This study investigates the cloud macro-and micro-physical characteristics in the convective and stratiform regions and their different responses to the seeding for mixed convective-stratiform clouds that occurred in Shandong province on 21 May 2018,based on the observations from the aircraft,the Suomi National Polar-Orbiting Partnership(NPP)satellite,and the high-resolution Himawari-8(H8)satellite.The aircraft observations show that convection was deeper and radar echoes were significantly enhanced with higher tops in response to seeding in the convective region.This is linked with the conversion of supercooled liquid droplets to ice crystals with released latent heat,resulting in strengthened updrafts,enhanced radar echoes,higher cloud tops,and more and larger precipitation particles.In contrast,in the stratiform cloud region,after the Silver Iodide(AgI)seeding,the radar echoes become significantly weaker at heights close to the seeding layer,with the echo tops lowered by 1.4–1.7 km.In addition,a hollow structure appears at the height of 6.2–7.8 km with a depth of about 1.6 km and a diameter of about 5.5 km,and features such as icing seeding tracks appear.These suggest that the transformation between droplets and ice particles was accelerated by the seeding in the stratiform part.The NPP and H8 satellites also show that convective activity was stronger in the convective region after seeding;while in the stratiform region,a cloud seeding track with a width of 1–3 km appears 10 km downstream of the seeding layer 15 minutes after the AgI seeding,which moves along the wind direction as width increases.

WHU-Grace01s:A new temporal gravity field model recovered from GRACE KBRR data alone

A new temporal gravity field model called WHU-Grace01s solely recovered from Gravity Recovery and Climate Experiment （GRACE） K-Band Range Rate （KBRR） data based on dynamic integral approach is presented in this paper. After meticulously preprocessing of the GRACE KBRR data, the root mean square of its post residuals is about 0.2 micrometers per second, and seventy-two monthly temporal solutions truncated to degree and order 60 are computed for the period from January 2003 to December 2008. After applying the combi- nation filter in WHU-Grace01s, the global temporal signals show obvious periodical change rules in the large-scale fiver basins. In terms of the degree variance, our solution is smaller at high degrees, and shows a good consistency at the rest of degrees with the Release 05 models from Center for Space Research （CSR）, GeoForschungsZentrum Potsdam （GFZ） and Jet Pro- pulsion Laboratory 0PL）. Compared with other published models in terms of equivalent water height distribution, our solution is consistent with those published by CSR, GFZ, JPL, Delft institute of Earth Observation and Space system （DEOS）, Tongji University （Tongji）, Institute of Theoretical Geodesy （ITG）, Astronomical Institute in University of Bern （AIUB） and Groupe de Recherche de Geodesie Spatiale （GRGS}, which indicates that the accuracy of WHU-Grace01s has a good consistency with the previously published GRACE solutions.

A preliminary study of level 1A data processing of a low-low satellite to satellite tracking mission

With the Gravity Recovery and Climate Experiment {GRACE） mission as the prime example, an overview is given on the management and processing of Level IA data of a low-low satellite to satellite tracking mission. To illustrate the underlying principle and algorithm, a detailed study is made on the K-band ranging （KBR） assembly, which includes the measurement principles, modeling of noises, the generation of Level 1A data from that of Level 0 as well as Level IA to Level IB data processing.

Design and Modeling of S Band Circular Patch and Ka Band Horn Antenna, Integration with Future Multifunctional Radio over Fiber Network

Radio over Fiber is an integration of microwave and optical fiber technologies having numerous benefits. RoF technology can give a scope of advantages including the capacity for backing multiple radio services and standards. In coming future, there is need of integrated wireless service with high speed satellite broadband and multifunctional indoor/outdoor antennas. Radio over fiber is one of the most favorite candidates to meet all these requirements of future multifunctional integrated wireless communication. Due to planer profile, small size and low cost patch antennas are most favorite to use for multi- frequency applications. In this paper, we present system level design for future multifunctional radio over fiber network. Under FTTH (Fiber To The Home) technology, it will be possible to use multi-frequency applications on single fiber medium. Firstly, we designed S band circular patch antenna (2.5 GHz) and Ka band (29 GHz) horn antenna. Circular patch antenna performance is estimated with different substrate height. After getting S parameters and far-field results, we did modeling of Radio over Fiber system over (10 Km) with same parameters from antenna results.

Progress on the use of satellite technology for gravity exploration

In this paper, the technological progress on Chinese gravity exploration satellites is presented. Novel features such as ultra-stable structure, high accurate thermal control, drag-free and attitude control, micro-thrusters, aerodynamic configuration, the ability to perform micro-vibration analyses, microwave ranging system and mass center trimmer are described.

A Ka-band wide locking range frequency divider with high injection sensitivity

This paper proposes a direct injection-locked frequency divider（ILFD） with a wide locking range in the Ka-band. A complementary cross-coupled architecture is used to enhance the overdriving voltage of the switch transistor so that the divider locking range is extended efficiently. New insights into the locking range and output power are proposed. A new method to analyze and optimize the injection sensitivity is presented and a layout technique to reduce the parasitics of the cross-coupled transistors is applied to decrease the frequency shift and the locking range degradation. The circuit is designed in a standard 90-nm CMOS process. The total locking range of the ILFD is 43.8% at 34.5 GHz with an incident power of –3.5 dBm. The divider IC consumes 3.6 mW of power at the supply voltage of 1.2 V. The chip area including the pads is 0.50.5 mm2.

A Ka-band low-noise amplifier with a coplanar waveguide(CPW)structure with 0.15-μm GaAs pHEMT technology

This investigation explores a low-noise amplifier （LNA） with a coplanar waveguide （CPW） structure, in which a two-stage amplifier is associated with a cascade schematic circuit, implemented in 0.15μm GaAs pseudomorphic high electron mobility transistor （pHEMT） technology in a Ka-band （26.540.0 GHz） microwave monolithic integrated circuit （MMIC）. The experimental results demonstrate that the proposed LNA has a peak gain of 12.53 dt3 at 30 GHz and a minimum noise figure of 3.3 dB at 29.5 GHz, when biased at a Vds of 2 V and a Vgs of-0.6 V with a drain current of 16 mA in the circuit. The results show that the millimeter-wave LNA with coplanar waveguide structure has a higher gain and wider bandwidth than a conventional circuit. Finally, the overall LNA characterization exhibits high gain and low noise, indicating that the LNA has a compact circuit and favorable RF characteristics. The strong RF character exhibited by the LNA circuit can be used in millimeter-wave circuit applications.

A 4 W K-band GaAs MMIC power amplifier with 22 dB gain

A 4 W K-band AIGaAs/InGaAs/GaAs pseudomorphic high electron mobility transistor （PHEMT） monolithic microwave integrated circuit （MMIC） high power amplifier （PA） is reported. This amplifier is designed to fully match for a 50 f2 input and output impedance based on the 0.15μm power PHEMT process. Under the condition of 5.6 V and 2.6 A DC bias, the amplifier has achieved a 22 dB small-signal gain, better than a 13 dB input return loss, and 36 dBm saturation power with 25% PAE from 19 to 22 GHz.

Design of on-chip 15-18 GHz ultra low noise amplifier

With rapid development communication system, high signal to noise ratio （SNR） system is required. In high frequency bandwidth, high loss, low Q inductors and high noise figure is a significant challenge with on-chip monolithic microwave integrated circuits （MMICs）. To overcome this problem, high Q, low loss transmission line characteristics was analyzed. Compared with the same inductor value of the lumped component and the transmission line, it has a higher Q value and lower loss performance in high frequency, and a 2-stage common-source low noise amplifier （LNA） was presented, which employs source inductor feedback technology and high Q low loss transmission line matching network technique with over 17.6 dB small signal gain and 1.1 dB noise figure in 15 GHz-18 GHz. The LNA was fabricated by WIN semiconductors company 0.15 μm gallium arsenide （GaAs） P high electron mobility transistor （P-HEMT） process. The total Current is 15 mA, while the DC power consumption is only 45 mW.