Abstract:This paper introduces two miniaturized antennas for either omnidirectional or unidirectional radiation. These two antenna designs are based on the manipulation of two electric and magnetic radiators. First, omnidirectional CP antennas have broad radiation coverage and can avoid the polarization mismatch problem, which are suitable for device-to-device (D2D) and satellite communications. Two horizontally placed electric and magnetic radiators excited with equal amplitude and 90 degree phase difference can produce omnidirectional CP pattern. This paper will present a 28 GHz compact wheel-shaped omnidirectional CP antenna. The entire antenna is printed on a dielectric disk with the diameter of only 4 mm. It has broad bandwidth and good electrical characteristics, which is ideal for compact 5G mobile terminals. Second, unidirectional CP antennas have high directivity and can avoid polarization mismatch problem, which have been widely used in satellite mobile terminals. Two orthogonally placed electric and magnetic radiators excited with equal amplitude and phase produce unidirectional cardioid-shaped radiation pattern. This paper will introduce an electrically small unidirectional CP antenna, which organically combines two metamaterial-inspired electric and magnetic radiator into a compact entity. This antenna is ideal for satellite communication and wireless power transfer applications.

Abstract:In this study, a compact, low-profile, top-hat monopole antenna is proposed. By designing a top hat for a monopole, the antenna profile reduces from 12.9 mm (0.25λ₀) to 2 mm (0.039λ₀) at acenter frequency of 5.8 GHz, which helps realize a low-profile antenna structure. The length of this top hat is 21 mm (0.41λ₀);therefore, the proposed antenna is compact. To match the proposed antenna around the center frequency, four metal holes connecting with the ground are added on the side of the top hat, and a lumped inductance element is added to the feeding port. Finally, a simple prototype is realized, which exhibits good matching around the center frequency of 5.8 GHz.

Abstract:In this research study, a compact circularly polarized antenna with a tilted beam is proposed on the basis of a pair of orthogonally oriented complementary dipoles. The proof-of-concept demonstrates that the proposed antenna mainly consists of a planar sectorial monopole antenna, shorting pin, and L-shaped ground plane. The shorting pin connects the monopole and the horizontal part of the ground plane to realize a loop antenna. Experimental results show that a maximum radiation gain occurs at the direction of θ=60°, φ=90°, and an axial ratio at values lower than 3 dB is approximately 6.2%. More importantly, by comparing the proposed antenna with existing circularly polarized tilted beam counterparts, it can be seen that the proposed one is more compact, which fulfills the requirement of miniaturization.

Abstract:This studyproposes a novel compact dielectric dual-polarized waveguide antenna. By usingdielectric materials, the physical dimensions of conventional air-filled waveguides can be effectively reduced. To mitigatestrong back-lobe radiation, this study proposes a method of designingrectangular slots on waveguide walls, theoperating principlesof which are similar to that of choke-ring structures. Compared to choke rings, the proposed rectangular slots exhibitseveral advantages;theyhave a simple structure and compact sizeand are easy to fabricate. Through full-wave simulation analyses, the proposed antenna was found to operate ata wide impedance bandwidth greater than 40% andexhibited a high gain of 8.6±0.6 dBi;it also demonstrated stable radiation performance over the operating bandwidth. These advantages imply that the proposed antenna can be used for various applications in X-band frequencies, such as satellite communication.

Abstract:A miniaturized metasurface antenna using capacitive loading is investigated. First, anovel miniaturized metasurface unit cell is proposed. By introducing a pair of capacitive-loading strips inserted along the diagonal of a square patch, a size reduction of 55% can be achieved for this miniaturized unit cell. Furthermore, a compact metasurface antenna of a 4×4 array is designed using the miniaturized unit cells, which is fed by a slot structure. The radiation mechanism of the metasurface antenna is revealed and explained using a characteristic mode analysis (CMA). To validate the design, a prototype of the proposed antenna is fabricated and measurements are taken. The measured -10 dB impedance bandwidthis 21.7%, while a gain of 6 dBi is observed within the operating bandwidth.

Abstract:4T4R MIMO antennas are commonly required by operators at base stations. Existing designs of these antennas exhibit several disadvantages, such as large dimensions, high wind loads, and high costs. Thus, a new compact MIMO antenna design can help overcome these limitations. However, when two low-band 4T4R antennas come to a compact design, the electromagnetic coupling between the two arrays will increase dramatically. This can cause several problems such as ultra-wide horizontal beam width, decrease in gain, and worse inter-system isolation. In this study, a novel antenna array design method is proposed to address this issue. Using hybrid bridges, which have a typical characteristic of different frequency points with different power divides, and horizontal beam-forming technologies, a better horizontal beam width can be achieved in compact two low-band antennas. The experimental results show that, with the proposed design, the two low-band antennas exhibit a 4T4R antenna sexhibita good performance in terms of horizontal beamwidth, gain, and inter-system isolation.

Abstract:A novel linearly polarized water antenna inclined at 45 degrees with a high front-to-back ratio (FBR) is proposed. The broadside radiation pattern is realized by using a dipole to feed the structure. The dipole is placed near the ground surfaceto force the energy to the nearest field, reducing the energy loss caused by the distilled water. The results show that an impedance bandwidth from 823 to 873 MHz for |S₁₁| < -10 dB with again of approximately 7.73 dBi and a high radiation efficiency (better than 70% through the whole operating band)are obtained.

Abstract:Based on the characteristic mode theory, a 16-port multiple-input multiple-output (MIMO) cube antenna design for an indoor environment is presented. First, a high-isolation 4-port MIMO antenna unit operating at 5.150-5.875 GHz is designed by exciting different modes of a rectangular plate simultaneously, based on a modal analysis using the characteristic mode theory. An artificial magnetic conductor (AMC) surface is introduced to replace the reflector of the original antenna, which greatly reduces the profile of the antenna;it is also used to surround the antenna to form a 16-port (4×4) MIMO cube antenna. This antenna fulfils the multi-port and multi-polarization requirement within a small space. The simulation and experimental results show that the antenna operates with a port reflection coefficient S_ii < -10 dB and port isolation |S_ij| > 20 dB in the 5.150-5.875 GHz band.

Abstract:Mu-negative (MNG) transmission linesare artificial structureswhereseries-loaded capacitors are used to effectively obtain negative permeability. Because they have apropagation constant of zero, MNG transmission linescan be used to design resonators with an infinite wavelength and a resonance frequency independent of size to realize compact antenna designs with wide bandwidths. In this study, a wide-bandwidth dipole antenna and a loop antenna with a segmented line structure based on an MNG transmission line are proposed and fabricated. The proposed dipole antenna can operate ata wide impedance bandwidth of 1.4 GHz (2.2-3.6 GHz, 48%) with a length of 107 mm (1.03λ₀@2.9 GHz) and exhibits stable E-plane radiation patterns. The proposed loop antenna can operate ata wide bandwidth of 1GHz (2.4-3.4 GHz, 34%) with a diameter of 52 mm (0.5λ₀@2.9 GHz). Moreover, the proposed loop antenna has a uniform current distribution;thus, radiation characteristics equivalent to those of a magnetic dipole can be obtained. The experimentaland simulation results demonstrate good agreement.

Abstract:Circularly polarized antennas play an important role in communication through satellite navigation, radar, and information confrontation. In this letter, a miniaturized circularly polarized antenna operating in the GPS L1 band (1.575 GHz) is proposed. The proposed antenna possesses the advantages of having a low profile, small size, and compact structure, which in turn imply superior omnidirectional circular polarization. The radiation structure of the proposed antenna comprises a four-axis arched patch and a direct feeding metallic pin. Four inner additional arcs and four shorting pins were introduced for achieving the antenna miniaturization. The proposed design was verified by employing the Ansoft HFSS 16.1 simulation tool. The simulation results indicate that the proposed circularly polarized antenna matches well at the frequency of 1.575 GHz. Furthermore, the axial ratio is found to be less than 3 dB at the operating frequency band and the peak gain can reach a value of 0.2 dBic.

Abstract:In this study, a high-gain square patch antenna based on the TM₅₀ mode is proposed. Owing to the operation of the TM₅₀ mode, there is a pair of reversed-phase currents comparing with the radiating edges on the surface of the antenna. By introducing transverse slots along the central line of the patch, each of the two reversed-phase currents are interrupted to circulate with little radiation;thus, the four side-lobes of the TM₅₀ mode can be suppressed well. Simultaneously, because the reversed-phase current is weakened, the slotted antenna is superposed by three in-phase currents, which providean effect equivalent to that of three antenna elements operating under the TM₁₀ mode. By adjusting the size of the slots, the maximum gain of the antenna can reach 13.3 dB.

Abstract:The use of consumer-class drones has become a new ground image acquisition platform. This paper proposes different route planning methods based on the tilt photography principle and the characteristics of consumer-class drones, which can be divided into full-coverage routes, encircling routes, vertical routes, and contour routes. In order to achieve efficient and stable tilt image acquisition, an unmanned aerial vehicle tilt photography ground station based on the Android language was designed and programmed. This ground station can drive drones to automatically perform tilt photography according to planned tasks, significantly reducing the difficulty and workload of tilt photography technology and improving the ability of consumer-level drones to perform tilt photography and product accuracy.

Abstract:Despite the continuous enrichment of music, the underlying music features are often overlooked when using traditional collaborative filtering. By multi-modal fusion of audio features and lyric information and supplementing the fusion information feature as a collaborative filtering recommendation, a multi-modal music recommendation system is proposed. This studyprimarily discusses the extraction of audio features and lyrics information and uses the LDA topic model to reduce the character dimension of the lyrics information. For the multi-model fusion problem, this study proposes an EFFC fusion method, and compares the results of multi-modal fusion with the results using single-mode. For result recommendations, the user interest model is established based on the multi-modal information feature with the input of LSTM networks to filter and optimize the user group. The results show that the multi-modal music recommendation system reduces the SSE of the result from 2.009 to 0.388 6, verifying the effectiveness of the method.

Abstract:Whether the administrative division adjustment is reasonable is not only directly related to the allocation of social and natural resources, but also to economic development and social stabilityin a region. A scientific approach to analyze the reasonableness of zoning adjustment is of enormous importance. However, the current regional administrative division adjustment in Nanjingis dominatedby qualitative evaluation methods and empirical judgmentas well as a lack of effective quantitative analysis, which has resulted in uncertainty in the analysis process. Therefore, based on geographic information system (GIS) technology, Nanjing's administration adjustments calculated from the hinterland model were compared with the actual adjustments since 1995. Next, the rationality of Nanjing's administrative division adjustmentwas evaluated. The evaluation results showed that the administrative division adjustment was consistent with the results calculated from the hinterland model, which illustrates the rationality of the actual adjustments. However, it is worth noting thatadministrative divisionproblems concern superstructure, in addition totheeconomic level, geographical scope, and populationsize of the area, which are alsoclosely related to political, cultural, historical, and other factors. Itcannot completely relyon the results ofquantitative analysis. The specificneedsofthe township should be consideredin a subsequentstudy.

Abstract:Visibility is one of the important meteorological factors, and low visibility affects the safe and efficient operation of expressway. Visibility calculation method based on video data is similar to the perception of human eyes, and has the adaptability to bad weather conditions or complex observation sites. Based on three weather processes of fog in Anhui province on October 17th, December 1st and 7th of 2016, the visibility calculation model were built by using gray mean square error of corresponding video image and visibility observation data of three highway sites in Anhui province. Results show that the modeled visibility can well reflect the actual visibility corresponding with the change of fog process. The proposed visibility calculation method based on video image is similar to the perception of human eyes, i. e., the higher the visibility, the higher the resolution of terrain features for human eyes, and the greater the variance of the monitoring image as well. However, due to the difference in monitoring principle and the environment properties, error exists between the observation data and the calculated results. Theoretically, the error is low under the conditions of fog with uniform spatial distribution, and the visibility meter being close to the surveillance camera.

Abstract:Based on the C-band radar echo intensity and radial wind data of Guangzhou Baiyun Airport, the precipitation amount estimation and the rain belt moving prediction are carried out for the heavy precipitation process in South China during the first flood season. In the strong precipitation background of abundant rainfall areas, the C-band radar has better ability to detect cloud rain refinement structures, although the echo intensity is attenuated. The radar data quality control processing can preserve the original characteristics of the radar data, effectively filter out clutter and noise, and alleviate the problem that the radar data has many clutter at low elevation angle scanning surface and the altitude difference along radial direction. The data processing provides a technique support for precipitation estimation. The optimized radar Z-I precipitation estimation method is only based on information of each scanning procedure, so its calculation is simple and fast. However, the cloud type difference on the same scanning surface is sensitive to the parameter values of the optimization method, when the same parameters are used in different clouds that will affect the estimation effect of precipitation. By separating areas of the radar cloud echoes on the same scanning surface and selecting rainfall stations, the optimization parameters can be determined according to different cloud echoes, which can improve the optimal radar precipitation estimation. According to the short characteristics of radar scanning time, the radar radial wind convergence line and the strong echo center position are identified, and the extrapolation method is used to predict the rain belt orientation, position and moving speed. The verification effect is good.

Abstract:Based on the precipitation data of 15 observational stations during the last 60 years in Anhui province, the spatial & temporal features of annual and seasonal changes for wet days, rainfall and rain intensity were studied. The spatial distribution shows that wet days and rainfall are more in southern than in northern area;the rain intensity is almost equal in middle and northern areas, but less than that in southern area. As for the seasonal change, the precipitation is the most in summer and the least in winter in all areas;the wet days differ obviously between south and north in spring and winter, and the difference of rain intensity is large between south and north in spring. Wet days, rainfall and rain intensity show a significantly positive correlation between each other on both annual and seasonal levels. The temporal variation shows that wet days has declined, while precipitation and rain intensity have increased, and the characteristics can be divided into two stages. The wavelet analysis shows that wet days exists inter-decadal periodic (about 10 a), precipitation declines while rain intensity is not pronounced. Quasi-periodicities of 5 a and 3 a exist during the 60 a period. Wet days have declined significantly in spring and autumn. Precipitation has roughly declined in spring and autumn, and increased in summer and winter. Rain intensity has increased significantly, especially in summer and winter. On both annual and seasonal levels, precipitation has significant positive correlations with wet days and rain intensity, which is stronger than the correlation between wet days and rain intensity.

Abstract:Based on monthly spring and autumn precipitation data during 1961-2010 from 73 meteorological stations in Hebei province and its vicinity, as well as the NCEP/NCAR reanalysis data during the same period, the variations of spring and autumn precipitation anomaly in Hebei province and its possible relationship with the middle and low level circulation are analyzed by using Singular Value Decomposition (SVD) analysis method. Results indicate that the uniformly dry/wet is the most common pattern for the spatial distribution of spring and autumn rainfall in Hebei, and the second pattern is a seesaw of dry/wet between southern and northern regions. When the negative anomaly over east Siberian Sea and positive anomaly from Northeast China to Japan Sea emerge at 500 hPa geopotential height fields in spring, the contemporaneous spring precipitation in most parts of Hebei, especially Shijiazhuang, is above normal;otherwise, precipitation in spring is below normal. When the negative anomaly over Northwest Europe emerges at 500 hPa geopotential height fields in autumn, the contemporaneous precipitation in most parts of Hebei, especially middle areas, is below normal;otherwise, the precipitation in autumn is above normal. The spring and autumn droughts in Hebei are related to the stronger Baikal blocking high (or high pressure ridge) and the East Asian trough, and the weakened 850 hPa seasonal south winds cause contemporaneous droughts in Hebei.

Abstract:With the continuous improvement in lightning observation method and instrument, lightning detection and location data are substantially improved in quality and have found wide applications. As a powerful formal language, regular expression has been extensively applied to process original lightning detection and location data, from data compilation and storage to data analysis and query. The regular expression can simplify the processing procedures and improve working efficiencies in data processing of lightning detection and location system. This paper introduces the application of C# based regular expression in lightning detection and location data processing on the. Net platform.