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.

Elephant Culture Matter for China’s Asian Elephants Conservation

Traditional anthropogenic impacts such as hunting,using as war-elephant,trading of ivory,paying tribute to the imperial court and so on,were once thought to be directly responsible for the rapid decline of Asian elephants in China.But in Yunnan Province,China,a unique human factor such as the traditional elephant culture of local ethnic minorities,is an important factor in the conservation of Asian elephants.In these areas,we investigated by means of village interviews,field surveys and data collection,the results show that the elephant culture of ethnic minorities has a great impact on people’s thoughts and behaviors,these traditional culture and belief(that mean taking elephant as the God,holding elephant as a belief,worshipping elephant and praise it)urges people to actively protect elephants and avoid more human-elephant conflicts.To enhance the public awareness of Asian elephant conservation,the Chinese Government or international environmental organizations should give higher attention and support to these elephant cultures.

Effect of nitrogen limitation on antioxidant qualities is highly associated with genotypes of lettuce(Lactuca sativa L.)

Antioxidants are highly beneficial to human health, and their accumulation in lettuce, one of the most popular leafy vegetables, depends on both genetic and environmental factors. Nitrogen(N) availability plays an essential role in regulating antioxidant accumulation, but the influence of genotype × N interactions on the antioxidant qualities of lettuce is poorly understood. Therefore, the present study investigated the variation of growth and antioxidant qualities of 20 lettuce(Lactuca sativa L.) genotypes(10 green lettuce genotypes and 10 red lettuce genotypes) under limited N(low N, LN) conditions and standard N(high N, HN) conditions. For all 20 genotypes, LN conditions reduced shoot(i.e., leaf) growth, but increased plant concentrations of vitamin C,glutathione, and phenolic compounds, with the exception of carotenoids, compared with HN conditions. Because of reduced biomass under LN conditions, not all lettuce genotypes exhibited increased antioxidant yields or total antioxidant capacity yield. The variation in antioxidant quality was primarily genetically determined. Generally, the green lettuce genotypes exhibited more pronounced increases in antioxidant yields and total antioxidant capacity yield than the red lettuce genotypes under LN conditions. These results suggest that even though LN conditions generally tend to improve the antioxidant qualities of lettuce, the extent of this effect is highly dependent on genotype. Therefore, genotype should be given priority in future studies that aim to improve antioxidant qualities in lettuce through N management.

Defense of COVID-19 by Human Organoids

Coronavirus disease 2019(COVID-19),caused by severe acute respiratory syndrome coronavirus-2(SARS-CoV-2),has created an immense menace to public health worldwide,exerting huge effects on global economic and political conditions.Understanding the biology and pathogenesis mechanisms of this novel virus,in large parts,relies on optimal physiological models that allow replication and propagation of SARS-CoV-2.Human organoids,derived from stem cells,are three-dimen-sional cell cultures that recapitulate the cellular organization,transcriptional and epigenetic signatures of their counterpart organs.Recent studies have indicated their great values as experimental virology platforms,making human organoid an ideal tool for investigating host-pathogen interactions.Here,we summarize research developments for SARS-CoV-2 infection of various human organoids involved in multiple systems,including lung,liver,brain,intestine,kidney and blood vessel organoids.These studies help us reveal the pathogenesis mechanism of COVID-19,and facilitate the development of effec-tive vaccines and drugs as well as other therapeutic regimes.