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International Journal of Antennas and Propagation
Journal Prestige (SJR): 0.233
Citation Impact (citeScore): 1
Number of Followers: 10  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1687-5869 - ISSN (Online) 1687-5877
Published by Hindawi Homepage  [339 journals]
  • Exploration of Intelligent Teaching Methods for Ideological and Political
           Education in Colleges and Universities under the Background of “Mass
           Entrepreneurship and Innovation”

    • Abstract: The core subject matter of the development of innovative and entrepreneurial talents in higher vocational colleges, as well as the solution to the social employment issue, is the investigation of intelligent teaching methods for ideological and political education in colleges and universities against the backdrop of “mass entrepreneurship and innovation.” Artificial intelligence presents challenges of lack of emotion in the process of ideological and political education innovation in colleges and universities under the background of AI. AI does not provide information resources, technology, and thinking opportunities for the innovation of ideological and political education in colleges and universities. Therefore, this research presents a facial expression recognition approach based on facial recognition technology to address the emotional problem in intelligent teaching methods. This method can effectively and accurately identify the facial expressions of students during learning so that intelligent tools can identify students’ emotions in time, make corresponding adjustments quickly, and improve teaching efficiency. According to this study’s experimental findings, the facial expression recognition approach based on the upgraded AlexNet achieves an average recognition accuracy of around 75%, while the fine-tuning method based on the VGG-Face model achieves an average recognition accuracy of about 88.5%. The method based on the VGG-Face model is better suitable for face recognition in intelligent education, which can determine the status of students in real-time and alter the lesson plan, as seen by the facial expression recognition accuracy rate based on the enhanced AlexNet being 13% higher.
      PubDate: Wed, 17 Aug 2022 13:35:00 +000
       
  • 5G Millimeter Wave Endfire Array Antenna with Printed Inverted-F Structure

    • Abstract: In this design, a novel inverted F antenna with a low profile feed structure is proposed for millimeter-wave (mmW) applications. The array element consists of a printed inverted F antenna and a L-shaped parasitic deflector, approximately forming a structure similar to the Yagi-Uda antenna. The gain could be increased and the impedance bandwidth could be broadened by the structure. And, it is important to realize the miniaturization of the antenna element by bending the parasitic deflector based on the traditional deflector without affecting the performance. The proposed antenna has a low feed substrate height (0.254 mm∼0.02λ0), which makes it easy to integrate with planar circuits. As proof, a 1 × 4 array model with an impedance bandwidth of 20.5% (23.0–28.3 GHz) is designed and measured. The inverted F array demonstrated is an important candidate for mmW applications due to its wide bandwidth, miniaturization, ease of integration with planar circuits, and low manufacturing cost.
      PubDate: Fri, 12 Aug 2022 13:35:03 +000
       
  • An Improved Power-Only Measurement Strategy for Calibrating Phased Array
           Antennas

    • Abstract: An improved power-only measurement method is proposed to calibrate phased arrays, which is aimed at solving two remaining problems: little contribution of one antenna element’s phase shifting to the whole array’s power and the ambiguity of solutions. The method includes four steps. Firstly, the random distributed phase of each element is adjusted to guarantee that it is −90° to +90° relative to the reference element. Secondly, the proper number of the elements shifting their phases together is approximately determined. Then, an invertible matrix is formed from the standard Hadamard matrix to split the array into different groups, which applies to an arbitrary number of elements; Finally, the array gets calibrated with an existing method. Numerical simulations and experiments are conducted to validate the effectiveness of the proposed method.
      PubDate: Fri, 12 Aug 2022 08:05:01 +000
       
  • A Low-Profile Broadband Circularly Polarized Metasurface Antenna Aperture
           Coupled by Shorted Annular-Ring Slot

    • Abstract: A low-profile (LP) metasurface antenna is proposed for broadband circularly polarized (CP) operations. The metasurface radiator, formed by a 5 × 5 array of square patches, has a microstrip line fed at its bottom through a shorted annular-ring slot centered on the ground plane. First, the characteristic mode analysis (CMA) methodology is employed to examine the intrinsic modes of the metasurface. Subsequently, a pair of mutually orthogonal modes is selected and excited by the feeding structure with a 90° phase difference to produce CP radiation. For the purpose of verification, a prototype antenna is developed, and the obtained data reveal that the antenna exhibits an impedance bandwidth of 43.9% ranging from 4.8 to 7.5 GHz (S11
      PubDate: Wed, 10 Aug 2022 08:35:01 +000
       
  • Parasitic Elements Shorted to Ground to Enhance the Bandwidth of a
           Dual-Polarized Antenna

    • Abstract: An ultra-wideband dual-polarized antenna covering multiple communication standards such as LTE700/GSM850/GSM900 is proposed in this paper. The antenna consists of two dipoles that are perpendicularly placed to each other. The two dipoles can generate +45°/−45° linear polarizations, respectively. Dual-loop structure is utilized as the arm of the dipole, while four parasitic patches with shorting walls are coupled to the dipoles to extend the operating bandwidth. The measured results show that the antenna has an impedance bandwidth of 101.4% (0.54 GHz–1.65 GHz) with a reflection coefficient less than −10 dB. The isolation between the two ports is larger than 22 dB, and the cross-polarization is less than −20 dB over the band. Good unidirectional radiation patterns are obtained.
      PubDate: Tue, 09 Aug 2022 10:20:02 +000
       
  • A Wideband Circularly Polarized Dielectric Resonator Antenna Using Inverse
           f-Shaped Slot Excitation with Parasitic Metal Structure

    • Abstract: In this paper, a single-fed wideband circularly polarized dielectric resonator antenna (DRA) is proposed. The antenna consists of a substrate, a cylindrical dielectric resonator, and four curved parasitic metal blocks that are rotated and placed around the dielectric resonator. The GND of the substrate is etched with an inverse f-shaped slot. The orthogonal working mode of the DRA is excited by the inverse f-shaped slot coupled to the microstrip, thereby obtaining circularly polarized radiation. The impedance bandwidth and axial ratio bandwidth of the antenna are improved by optimizing the structure of the inverse f-shaped slot and the shape and size of curved parasitic metal blocks, and finally, a circularly polarized dielectric resonator antenna with significant bandwidth advantages is obtained. The antenna is simulated, fabricated, and measured. The measured results show that the proposed circularly polarized DRA has an impedance bandwidth of 58.5% (2.61–4.77 GHz) and an axial bandwidth of 55.2% (2.75–4.85 GHz) and finally achieves an effective axial bandwidth of 53.7% (2.75–4.77 GHz), the peak gain of 6.84 dBi, and average efficiency of 90.78%, with excellent overall performance.
      PubDate: Tue, 02 Aug 2022 08:35:01 +000
       
  • Mitigating GNSS Multipath Effects Using XGBoost Integrated Classifier
           Based on Consistency Checks

    • Abstract: Under the influence of urban building roads, especially interference from multipath effects, global navigation satellite system (GNSS) receiver-related output signal distortion can affect the robustness of the positioning system and the final positioning accuracy. To deal with the above problems, this paper proposes a two-layer consistency-checks (CC) positioning model based on eXtreme Gradient Boosting (XGBoost) integrated learner. First, the model excludes the abnormal values from the correlated output of the first layer by the classical statistical distribution test method. Then, the remaining available measurements are used as the second-layer input, and the measurements are used as learning data using an integrated machine learning method, XGBoost, to efficiently detect and identify non-line-of-sight (NLOS), LOS, and other reflective multipath signals. In order to better mitigate errors in the dynamic relative positioning process, the second-layer checking process uses dynamic pseudorange differencing technique (DPDT) and weighted least squares method (WLS) to smooth the output outcome of the receiver. In the experimental part, we compare and analyze the proposed method with the existing methods from different perspectives in this paper, respectively. The results show that the performance of the model is significantly improved after applying the CC method, in which the average classification accuracy of the multipath signals in the target feature set can reach 91.6%. According to the final positioning results, the proposed method shows a significant accuracy improvement compared to the existing research methods.
      PubDate: Mon, 01 Aug 2022 07:50:02 +000
       
  • Identification of Pneumonia in Chest X-Ray Image Based on Transformer

    • Abstract: The research of application models based on traditional convolutional neural networks has gradually entered the bottleneck period of performance improvement, and the improvement of chest X-ray image models has gradually become a difficult problem in the study. In this paper, the Swin Transformer is introduced into the application model of pneumonia recognition in chest X-ray images, and it is optimized according to the characteristics of chest X-ray images. The experimental results based on the model in this paper are compared with those of the model built with the traditional convolutional neural network as the backbone network, and the accuracy of the model is proved to be greatly improved. After the comparison experiments on two different datasets, the experimental results show that the accuracy of the model in this paper improves from 76.3% to 87.3% and from 92.8% to 97.2%, respectively. The experiments show that the accuracy of image enhancement based on the features of chest X-ray images in this model will be higher than the accuracy without image enhancement. In the experiments of this paper, the identification decision factors in the chest X-ray images were extracted by grad-cam combined with a transformer to find the corresponding approximate lesion regions.
      PubDate: Mon, 01 Aug 2022 06:50:01 +000
       
  • Characteristic Mode-Based Neutralization Line Design for MIMO Antenna

    • Abstract: Based on the theory of characteristic modes (TCMs), this paper proposes a systematic design procedure to guide the design of a neutralization line (NL) for a dual-band multiple-input-multiple-output (MIMO) antenna to achieve high isolation. According to the direction of the current flow of significant characteristic modes, coupling and uncoupling modes are identified and a metal NL is appropriately designed to cancel the coupling modes. More specifically, it introduces new currents opposite in direction to the original coupling characteristic currents, thus reducing mutual coupling. Compared with the traditional NL design method, the proposed approach simplifies the optimization process and saves lots of optimal design time. As an illustration of the proposed design method, we design another dual-band antenna operating in the WLAN bands with a compact size of 50 mm × 48 mm × 0.8 mm and minimum edge‐to‐edge space between the radiating elements with 0.033λ0 of the lower band. The impedance bandwidths for S11 ≤ -10 dB are 0.42 GHz (2.27–2.69 GHz) and 0.24 GHz (5.6–5.84 GHz). A fabricated prototype shows good agreement between the measured and simulated results. The introduced NL improves the isolation degree by about 18 dB for the 5.8 GHz band, and the total efficiency of the antenna was also improved. In addition, the proposed antenna also has a low envelop correlation coefficient (ECC 
      PubDate: Sat, 30 Jul 2022 08:20:04 +000
       
  • Single-Layer Planar Monopole Antenna-Based Artificial Magnetic Conductor
           (AMC)

    • Abstract: In this paper, a coplanar waveguide (CPW)-fed patch antenna is fabricated on a layer of metasurface to increase gain. The antenna is fabrication on Roger substrate with a thickness of 0.25 mm, with the overall dimension of the proposed design being 45 × 30 × 0.25 mm3. The size of the patch antenna is 24 × 14 × 0.25 mm3, and the AMC unit cell is 22 × 22 × 0.25 mm3. This metasurface is designed based on the split-ring resonator unit cells forming an array of the artificial magnetic conductor (AMC). Meanwhile, the antenna operation on 3.5 GHz is enabled by etching a split-ring resonator slot on the ground plane with a small gap to enhance antenna gain and improve impedance bandwidth when integrated with a metasurface. This simulation planer monopole antenna is applied for 5G application. The experimenter test is applied for the antenna performance in terms of return loss, gain, and radiation patterns. The operating frequency range with and without MTM is from 3.41 to 3.68 GHz (270 MHz) and 3.37 to 3.55 GHz (180 MHz), respectively, with gain improvements of about 2.7 dB (without MTM) to 6.0 dB (with MTM) at 3.5 GHz. The maximum improvement of the gain is about 42% when integrated with the AMC. The AMC has solved several issues to overcome the typical limitation in conventional antenna design. A circuit model is also proposed to simplify the estimation of the performance of this antenna at the desired frequency band. The proposed design is simulated by CST microwave studio. Finally, the antenna is fabricated and measured. Result comparison between simulations and measurements indicates a good agreement between them.
      PubDate: Thu, 21 Jul 2022 13:20:02 +000
       
  • The Effect Model of College PE Teaching Reform Based on Moral Education

    • Abstract: In order to further promote the integration of moral education and college PE teaching and improve the effect of college PE teaching reform in the new era, a research on the effect model of college PE teaching reform based on moral education is put forward. Based on the demand background of moral education, the personalized PE teaching reform path is proposed, and the factors that affect the improvement of college PE teaching reform are analyzed with the help of mathematical statistics from the five aspects: teaching, teachers, students, field equipment, and culture system. Through KMO and Bartlett sphere test analysis, it is found that the explanatory variance contribution of the five factors is 16.910%, 13.757%, 11.835%, 10.973%, and 10.065%, respectively, and the cumulative variance of the five influencing factors is 63.541%, meeting the minimum standard of 60%, which also confirms the feasibility and effectiveness of integrating moral education into physical education teaching reform.
      PubDate: Tue, 19 Jul 2022 08:50:03 +000
       
  • Design of Wideband Circular-Slot Antenna for Harvesting RF Energy

    • Abstract: The design of a wideband circular-slot antenna for RF signal harvesting is reported in this work. The proposed design frequency range accommodates the leading contributors to the available RF signals accessible by the RFEH node. These widely utilized frequency bands comprise GSM1800, UMTS2100, Wi-Fi2.450, and LTE2600. The antenna geometry comprises circular-ring radiating component filled with two orbital circular and rectangular slots. At the bottom plane, a pair of rectangular and semirectangular-circle slits are integrated. The antenna presented is designed on a double layer of 1.6 mm high FR-4 substrate. The source antenna achieved a simulated and measured impedance bandwidth (BW) of 1.510 and 1.590 GHz, amounting to 68% and 73% fractional BW (FBW), covering -10 dB reflection coefficient ( S11 ) between 1.640 to 3.150 GHz and 1.550 to 3.140 GHz, in that order. The wideband circular-slot source antenna realized a maximum measured gain of 1.88, 2.13, 2.81, 3.22, and 4.32 dBi for 1.800, 2.100, 2.450, 2.650, and 3.20 GHz, respectively. The proposed design dimension on the printed board is 0.61  × 0.70 . The improved antenna gain is obtained from a circular parasitic patch coupled to the defected ground structure (DGS) for better RF energy harvesting in an ambient environment.
      PubDate: Tue, 19 Jul 2022 08:35:03 +000
       
  • Applying Polarimetric Target Decomposition to 2D Turntable ISAR Imagery of
           a Complex Vehicle

    • Abstract: The capabilities of polarimetric target decomposition in SAR-based ATR applications are investigated by using 2D turntable ISAR imagery of a T-72 tank. To characterize target’s anisotropic scattering properties, wide-angle case is considered through the employment of a distinct polarimetric analysis procedure based on angular averaging of the covariance matrix. The results of the application of the three types of coherent decomposition, that is, Pauli, Krogager, and Cameron decomposition, and one incoherent decomposition, that is, eigenvector/eigenvalue decomposition, are analyzed and compared in terms of the identification of the physical scattering mechanisms. The usefulness of the various secondary parameters, including orientation, symmetry, and entropy, is also discussed. It is found that Pauli and Krogager decomposition can be readily applied for quick discrimination between the odd- and even-bounce reflectors. For a more detailed description of scattering mechanisms, either the Cameron or eigenvector/eigenvalue decomposition can be employed since their classification images are shown to be mostly consistent with each other. The results demonstrate that the decomposition features can be effectively utilized in subsequent ATR processes.
      PubDate: Tue, 19 Jul 2022 08:35:03 +000
       
  • VHF/UHF Wideband Slim Monopole Antenna with Distributed Matching
           Structures

    • Abstract: This paper presents a wideband monopole antenna with distributed matching structures operating on VHF/UHF bands. The antenna consists of a slim rectangular metal strip with a T-type slot etched on the upper half, two rectangular slots on the lower half, and two rectangular plates soldered with the bottom end of the main strip. The antenna is installed on a metal case which serves as ground. To achieve a wide bandwidth, an impedance matching network consisting of the distributed structures, which are composed of two metal plates and a metal thin strip, is devised and integrated with the main radiating strip. The T-type slot near the top tip of the main strip is used for the miniaturization of the antenna. The proposed antenna is fabricated and measured, and the measured results are in good agreement with the simulated results. The sizes of the proposed antenna and the case are 0.19λmax × 0.014λmax and 0.17λmax × 0.1λmax × 0.034λmax, respectively. The operating bandwidth is from 203.7 to 516.9 MHz (2.54 octaves) with the condition of VSWR ≤ 3 : 1. This antenna has a slim structure, a wide bandwidth covering partially VHF and UHF bands, and omnidirectional radiation patterns, so it can be the candidate for the applications of backpacked radio stations in military communication scenarios.
      PubDate: Mon, 18 Jul 2022 17:35:02 +000
       
  • A Dual-Polarized Dual-Band Patch Antenna Based on Orthogonal Modes
           Manipulation

    • Abstract: In this paper, a co-caliber structure for dual-polarized dual-band (DPDB) radiation is presented through cross-polarized modes manipulation. After introducing slots and a connection branch into a typical patch antenna, two orthogonal radiation modes with different electrical-length achieved a meandered current mode at the lower frequency and a patch radiation mode at the higher frequency. The radiation patterns at both frequencies are patch-like, benefitting from certain feeding designs. The dual frequencies can be manipulated independently since their working modes are independent. In addition, compared with the traditional patch, the proposed antenna performs a higher aperture efficiency with a miniaturized antenna dimension. The antenna is finally fabricated and measured. The measured results showed that the antenna is evidently cross-polarized working at 10.38 GHz and 14.2 GHz and the gains are 5.57 dB and 6.82 dB, respectively. With the advantages of being compact, easily fabricated, and integrated, the proposed antenna can be potentially utilized in antenna research, polarization manipulation, multichannel communication system, and so on.
      PubDate: Mon, 18 Jul 2022 11:50:03 +000
       
  • A Method to Improve the Performance of Arrays for Aperture-Level
           Simultaneous Transmit and Receive

    • Abstract: The simultaneous transmit and receive (STAR) system needs to establish sufficiently high isolation between the transmitter and the receiver in order to play its role. However, due to the nonlinear characteristics and the accompanying noise of the active devices in the system, the coupling from the transmit channel to the receive channel cannot be accurately estimated in massive arrays, making it hard to improve the isolation between the transmit and receive channels. This paper proposes a new method to enhance isolation for aperture-level transmitting array and receiving array. The method uses the transmit and receive beamforming technology and aperture optimization technology to enhance the isolation between the transmitting aperture and the receiving aperture. The experimental results show that when the transmit power of an 8-element Vivaldi array is 30 W, the effective isotropic isolation (EII) peak value reaches 153.9 dB. The noise floor of the system is −89.9 dBm. Compared to only using aperture optimization and only using beamforming technology, the scheme in this paper, respectively, improves the isolation of 20.69 and 6.17 dB.
      PubDate: Mon, 18 Jul 2022 11:50:02 +000
       
  • Using the WSPR Mode for Antenna Performance Evaluation and Propagation
           Assessment on the 160-m Band

    • Abstract: In the last couple of years, the use of weak signal propagation reporter (WSPR) has grown significantly in the radio amateur community and beyond. This protocol allows to probe potential propagation paths between radio transceivers, operating at a low-power level. The protocol decodes the received signals and translates them into appropriate signal-to-noise ratio levels, which reveal the possible propagation paths between the transmitter and receiver using ionospheric reflections. In this article, specifically the 160-m radio amateur band is addressed. This band used less intensity for WSPR communication, compared to the other radio amateur bands (80 m and 40 m). Additionally, the 160-m band has specific features such as the link between propagation performance and the Earth’s electron gyro-effect. The aim of this article is to address these features experimentally. First, two identical 160-m band WSPR receiver stations are conditioned to compare the performance of different 160-m band antennas. Each setup, separated by a limited distance, generates almost identical SNR reports, allowing the comparison between the two antennas. Second, a more extended experimental investigation of the propagation path performance on the 160-m band reveals information on the radio wave behaviour between the transmitter and receiver. The first experiment allowed the identification of the most optimal antenna, specifically in the 160-m band. The second experiment shows that the SNR values can vary depending on the polarization shift of the received signal. Possibly, this can be linked to the effect of the magnetic field of the Earth via the electron gyro-frequency.
      PubDate: Fri, 15 Jul 2022 11:50:09 +000
       
  • Instantaneous Bandwidth Enhancement for Variable Inclination Continuous
           Transverse Stub Antenna

    • Abstract: In this paper, a method was developed to achieve the instantaneous bandwidth enhancement of a variable inclination continuous transverse stub (VICTS) antenna. The aperture of the VICTS antenna was divided into a subarray, and the true-time delay was introduced to reduce the dispersion of the antenna. The method has low loss and is suitable for the entire beam scanning range. To demonstrate this method, a proposed VICTS antenna composed of 2 × 2 subarrays was designed and simulated. Compared with the traditional VICTS antenna of the same aperture size, the gain loss was reduced by at least 52% and the 3/4-dB gain-loss bandwidth increased from 2.5% to 4.2%. The impedance bandwidth of 16.7% with the value of each subarray below −15 dB was achieved, and the sidelobe of the whole antenna was below −10 dB. The antenna radius was 0.34 m, and the aperture efficiency was 14.8%. The proposed antenna is a suitable candidate as a gateway station antenna for low earth orbit (LEO) satellite communication.
      PubDate: Fri, 15 Jul 2022 04:35:01 +000
       
  • Broadband Circularly Polarized Antennas with Compact Radiator Using
           Characteristic Mode Analysis

    • Abstract: In this paper, a general design procedure of simple four steps for wideband circularly polarized (CP) antenna based on characteristic mode analysis (CMA) is proposed. CMA is performed to investigate the CP generation principle of the proposed radiator. Modal currents and their corresponding radiation patterns are studied for mode selection and feeding placement to achieve CP operation. Then, two feeding mechanisms are introduced to constitute two CP antenna prototypes, which are further analyzed and optimized by CMA. With the physical insight into radiation characteristics of the prototypes, two antennas employing coplanar waveguide (CPW) as feed are designed and optimized by full-wave simulation. To validate the design procedure, both antennas with the same dimension (35 × 40 × 1.6 ) are fabricated and measured. The experimental results show that both of the antennas have good CP radiation performance with a peak gain of 4.0 dBic and 2.5 dBic and axial ratio bandwidth (ARBW) of 48.3% and 44%, respectively. In addition, the experimental results are in good agreement with the radiation information provided by CMA.
      PubDate: Tue, 12 Jul 2022 11:35:02 +000
       
  • Development of Urban Waste Recycling Industry from the Perspective of
           Ecology

    • Abstract: Urban garbage has become an important field affecting the healthy development of urban ecology, and urban ecological environment protection has naturally become a crucial part in the process of modern urban development. Deepening the relevant concepts of ecological and environmental protection also makes modern cities pay attention to the recycling and utilization of waste resources. This work is combined with the development status of urban waste recycling industry. Taking urban construction waste and domestic waste as examples, this paper focuses on the operation model and development path of urban waste recycling industry. For example, in the aspect of domestic waste treatment, the resource industrialization path of incineration fly ash is proposed, focusing on the water washing and dechlorination of incineration fly ash, the production of unburned ceramsite from water washed fly ash, and the separation and recovery of inorganic salts in fly ash water washing solution. The results show that the recoveries of NaCl, KCl, and CaCl2 are 96.21%, 95.85%, and 94.72%. Through the analysis of social, environmental, and economic benefits, the government, scientific research institutions, and enterprises are encouraged to make joint efforts to develop the construction waste recycling industry, so as to fundamentally solve the current situation of “mountains of garbage and cities surrounded by garbage” in China.
      PubDate: Tue, 12 Jul 2022 10:20:02 +000
       
  • Marketing Model of Tourism Enterprises Based on New Media Environment

    • Abstract: New media is a scientific and technological product under the background of the new era, and now new media technology has been widely used in all aspects of social development, and it has spawned the arrival of the new media era. In the new media environment, the survival and development environment faced by enterprises have undergone earth-shaking changes; if you still follow the traditional marketing methods, it will not only reduce the effectiveness of marketing but also because of the deviation from the development requirements of the times be eliminated, bringing threats to the survival and development of enterprises. The development of new media, represented by the Internet and mobile phones, has brought great changes to various industries in the world including tourism. The market size of the travel network is expanding, and online sales are soaring. At the same time, all kinds of tourism organizations often have blind optimism in the construction of tourism networks and lack of reasonable application means, so that tourism network marketing is far from exerting its potential in reality; on the one hand, it cannot provide transaction services that satisfy both supply and demand; on the other hand, it also affects the economic benefits of tourism organizations. Compared with the rapid development of the tourism media industry, the theoretical research related to the actual situation lags significantly. Although the number of related studies at home and abroad is increasing, most of them stay at the level of explanation and introduction, and the analysis of the tourism industry chain is not enough. The breadth and depth of the study are sorely lacking. The future letter needs to summarize the successes and failures of the development of the tourism media industry from a theoretical height and carry out theoretical improvement to guide practice, and it also needs to strengthen forward-looking research, summarize the laws and models, and put forward practical implementation plans to improve the overall development level of the tourism and media industry. Aiming at the problem of new media marketing strategy in shopping tourism scenic spots, this paper applies descriptive research, questionnaire survey, statistical processing, mathematical model, and other research methods to analyze the characteristics of new media such as prominence of personalization, increased audience selectivity, and diversified forms of expression presented by new media compared with traditional media, as well as the differences between the two in terms of communication status, dominant state, and audience state. 4I Marketing theory is applied to new media marketing, the changes in the marketing environment and marketing needs under the background of new media, and the extensive impact of these changes on the marketing mix strategy; the basic strategies and expected effects of new media marketing of tourism enterprises are studied from the aspects of product, price, channel, and promotion; the IPA model is constructed, and the empirical analysis of the shopping tourist attractions of Changshu Garment City in China is carried out. Through the research of this paper, in theory, the understanding of new media marketing is enriched, and in fact, it provides guidance for optimizing the new media marketing strategy of tourist attractions.
      PubDate: Mon, 11 Jul 2022 07:50:01 +000
       
  • Ultra-Compact Slitted Flower-Shaped Dual-Band Monopole Antenna for Modern
           Portable Devices

    • Abstract: A meanderingly slitted bio-inspired (MSB)-shaped antenna is presented in this work. The footprint of the proposed MSB antenna is 12 × 10 mm2. The MSB antenna proposed in this operates at 2.1 GHz and 5.2 GHz frequencies with a bandwidth of 70 MHz and 570 MHz and a radiation efficiency of 52.5% and 96%, respectively, which is suitable for UMTS, radio navigation, Long Term Evolution (LTE), and 5 GHz Wireless Local Area Network (WLAN) applications. The proposed MSB antenna demonstrates a peak gain of 2.9 dBi at 5.2 GHz and an omnidirectional radiation pattern at both E-plane and H-plane in both operating bands. The fabrication and measurement of the proposed antenna prototype are presented. The parametric study of the proposed structure is performed and presented. Therefore, the proposed antenna is a promising candidate for modern portable devices.
      PubDate: Fri, 08 Jul 2022 10:35:03 +000
       
  • Two-Step Frequency Estimation of GNSS Signal in High-Dynamic Environment

    • Abstract: To improve frequency accuracy which is affected by two parameters in high-dynamic acquisition, we propose a two-step frequency estimation method based on the mean frequency (MF) model for high-dynamic parameters estimation. The first step is based on the discrete chirp-Fourier transform (DCFT) for coarse MF estimation, where the MF accuracy and frequency search step are derived. In the second step, the maximum likelihood estimation process (MLEP) is adopted for fine MF estimation. Compared with state-of-art methods, it is verified that the two-step method can improve the detection probability in coarse MF estimation and improve the MF accuracy with low computational burdens under conditions with a moderate signal-to-noise ratio (SNR).
      PubDate: Thu, 07 Jul 2022 11:20:04 +000
       
  • A Method for Predicting Coupling Laws of UWB EMP to Millimeter Wave
           Detector

    • Abstract: The millimeter wave detector has been widely applied in short-range detection systems. However, it can be easily disturbed by the ultra-wideband electromagnetic pulse (UWB EMP). In this paper, we proposed a simplified model to investigate the coupling laws of UWB EMP to the millimeter wave detector. With the help of finite integration technology (FIT), the coupling process can be visualized, and the most sensitive pose and the coupling path are analyzed. The irradiation tests are carried out to verify the simulation results. The results show that the shielding effectiveness (SE) of the detector in the vertical state is the worst, and the UWB EMP enters the detector mainly through the circular opening. Under the irradiation of UWB EMP, the detector shows three phenomena: interruptions, constant false alarms, and damage. The interruptions can be recovered by power reset, while the constant false alarms and damage are irreversible effects. The results can be employed to reinforce the electromagnetic compatibility (EMC) of the millimeter wave detector. With the increasing use of short-range detection systems, the EMC of existing products must be improved.
      PubDate: Wed, 06 Jul 2022 09:35:02 +000
       
  • A Miniaturized Wideband Planar Bow-Tie Slot Antenna with Asymmetric CPW

    • Abstract: In this paper, a novel miniaturized wideband planar bow-tie slot antenna is proposed. For the purpose of miniaturization and wide bandwidth, the effects of the dimension and shape of the bow-tie slot and feed structure are analyzed. This antenna adopts a water droplet slot, fed by an optimized asymmetric coplanar waveguide (CPW). By adjusting the feeding line, the impedance characteristic of the antenna is greatly improved that leads to a broader bandwidth. The proposed antenna operates from 2.8 GHz to 5.25 GHz with a gain of 3.8 dB. Compared with the traditional triangle bow-tie antenna, the relative bandwidth of the proposed antenna is broadened to more than 61%, while the size is reduced by about 36%, which indicates the proposed antenna is suitable for a variety of wireless applications.
      PubDate: Tue, 05 Jul 2022 11:20:02 +000
       
  • A 3-Dimensional Multiband Antenna for Vehicular 5G
           Sub-6 GHz/GNSS/V2X Applications

    • Abstract: A compact multiband monopole antenna is proposed for vehicular roof top shark-fin applications. The proposed multiband antenna covers 5G sub-6 GHz and LTE bands starting at 617 MHz to 5000 MHz and the higher GNSS band from 1559 to 1606 MHz as well as the V2X band at 5900 MHz. The presented antenna is a three-dimensional monopole antenna with two branches to cover the required bands with compact size to fit inside a roof top shark-fin. The long antenna branch covers the lower cellular frequency band from 617 to 960 MHz, while the short branch covers the higher frequency band from 1559 to 6000 MHz. The presented antenna is mounted on a double-sided FR4 PCB and is feeded through a short cable. The proposed antenna covers multiple frequency bands with compact size (H  x  L  x  W) of 58 × 37 × 17 mm3. The antenna is simulated and optimized, and then, a prototype is fabricated, and its radiation characteristics are measured when mounted on one-meter ground plane and on a vehicle’s roof. The maximum measured linear average gain is 3 dBi at 1900 MHz, and the maximum measured efficiency is 88% at 787 MHz. The active GNSS antenna gain is measured using an LNA with good isolation. A good agreement is achieved between the simulated and measured results when compared in terms of voltage standing wave ratio (VSWR), radiation patterns, linear average gain (LAG), and antenna efficiency.
      PubDate: Tue, 05 Jul 2022 08:50:02 +000
       
  • A DSP-Controlled Permanent Magnet Synchronous Motor Control System for
           Hybrid Vehicles

    • Abstract: Compared with other motors, the permanent magnet synchronous motor (PMSM) is small and occupies less space. At the same time, its weight is relatively light, so it is more in line with the development trend of hybrid electric vehicle (EV) drive motor lightweight miniaturization and has been widely used. This article studies a DSP-controlled PMSM control system for hybrid vehicles. Firstly, the motor drive control system is mainly controlled by DSP2812 chip. Then, a maximum torque current ratio control method was proposed to optimize the energy efficiency of hybrid vehicles based on PMSM. The longitudinal dynamic model of the moving hybrid vehicle was obtained by force analysis. Combined with the basic equation of PMSM and the transmission system of the hybrid vehicle, the mathematical model of PMSM-EV was established. The experimental results show that the maximum torque current ratio control method applied to hybrid vehicles can effectively reduce the loss, improve the efficiency and dynamic performance, and solve the endurance problem of hybrid vehicles to a certain extent. This advantage is significant in the dynamic acceleration and deceleration of hybrid vehicles.
      PubDate: Mon, 04 Jul 2022 11:05:05 +000
       
  • Dynamic Characteristics Analysis and Applications of Electromagnetic
           Environment Based on Group Perception

    • Abstract: In collectively perceiving an electromagnetic environment, the discrete or statistical method is used to characterize its characteristics. The information received by the sensor is not correlated with each other; therefore, there is no way to obtain the integral dynamic characteristics of an electromagnetic environment. Based on the statistical manifold and the information geometry theory, this paper takes group perception sensors in an electromagnetic space as an associated whole to measure an electromagnetic field in its space. The probability density function of the field distribution measured at any moment is mapped on to a statistical manifold. The “information distance” between the probability density functions of measurement samples at different moments of the statistical manifold is solved to reveal the changes in the whole electromagnetic environment. Simulations are carried out in assumed electromagnetic environments. The simulation results show that when a target enters the electromagnetic space and as its electromagnetic characteristics and positions change, the distribution of “KLD information distances” of its electromagnetic environment changes as well. The method can perceive the RCS of target with −26 dBsm and connect the target with its position information, indicating that the use of the “KLD information distance” distribution can characterize the integral dynamic characteristics of an electromagnetic environment.
      PubDate: Mon, 04 Jul 2022 10:50:05 +000
       
  • A Novel Model for Calculating Uplink-Downlink Spectral Efficiency in
           Cooperative Communication MIMO Systems

    • Abstract: Cooperative communication that enables the use of relays between a base station (BS) and end users is an effective technique against fading to improve network performance, especially in increasing spectral efficiency (SE) and network coverage. However, systems that use cooperative communication have weaknesses in the structure, such as resistance to latency and an increase in the bandwidth of substitute users (SU), which can be improved by optimizing the relay selection method effectively. The system due to insufficient spacing between antennas and insufficient scattering in the channel has spatially faded that leads to spatial correlation. We use Kronecker statistical model correlated multiantenna channels to implement detection techniques and eliminate interference in cooperative communication. The validity of the Kronecker model lies in the fact that correlation coefficients of transmission are independent of the receiving antennas. In other words, the spatial correlation model separates both ends of the communication link. Therefore, using the minimum mean-squared-error (MMSE) technique, we have removed the need for optimal elimination of interference between SU and relay service provider or primary user (PU). Regardless of BS performance, the scope of this work is restricted to the layer after the BS in the interaction between the service providers and substitute users. The primary purpose of the presented method is to improve the spectral gain through the elimination of interference. Simulation results show about 10% of SE improvement along with considerable traffic gain.
      PubDate: Wed, 29 Jun 2022 11:35:07 +000
       
  • Four Element MIMO Antenna Systems with Decoupling Lines for High-Speed 5G
           Wireless Data Communication

    • Abstract: A low-profile planar multiple-input multiple-output (MIMO) antenna consisting of four elements with isolation improvement is proposed for 5G mm Wave (24–40) GHz applications. Each radiating element of the MIMO antenna comprises of a microstrip-fed tilted spade-shaped radiator with four asymmetrical slots and a partial ground plane. The antenna is optimized to resonate at 35 GHz covering a wide impedance bandwidth from 23.9 to 40.1 GHz. Two cross lines are then loaded between the antenna elements to improve the isolation . The MIMO structure with the decoupling lines is fabricated and tested. The measured results are in good correlation with the simulated results. Other MIMO performance metrics such as the envelope correlation coefficient (ECC), channel capacity loss (CCL), diversity gain (DG), and total active reflection coefficient (TARC) are examined, and the results are found to be satisfactory for the device to be used for mm-wave 5G MIMO applications. Also, the antenna’s performance metrics such as radiation efficiency, gain, and radiation patterns over the operating band are presented.
      PubDate: Sat, 25 Jun 2022 06:50:05 +000
       
 
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