The growing demand for advanced wireless communication, high-resolution imaging, and innovative medical applications in the Terahertz (THz) frequency range has driven remarkable developments in meta-surface-based antennas. This comprehensive review delves into the cutting-edge advancements, novel designs, and practical applications of meta-surfaces in the THz spectrum. The review begins by exploring the materials employed in meta-surfaces and their crucial role in achieving efficient THz operation. It delves into the realm of polarization diversity, revealing innovative approaches to harnessing the potential of meta-surfaces for polarization control and conversion. A key area of focus is beam-steering technology, with a thorough investigation into beam-steering techniques that have significant implications for enhancing wireless communication, high-resolution imaging, and the internet of things. The paper highlights the potential of these techniques in addressing real-world challenges and advancing THz technology. Furthermore, this review provides an in-depth examination of the innovative antenna designs tailored for THz applications, shedding light on their characteristics and benefits. It also explores the exciting possibilities of THz technology within the medical field, including precise bio sensing and cancer cell detection.
{"title":"A systematic review of meta-surface based antennas for Thz applications","authors":"Nipun Sharma;Amrit Kaur","doi":"10.1029/2024RS007980","DOIUrl":"https://doi.org/10.1029/2024RS007980","url":null,"abstract":"The growing demand for advanced wireless communication, high-resolution imaging, and innovative medical applications in the Terahertz (THz) frequency range has driven remarkable developments in meta-surface-based antennas. This comprehensive review delves into the cutting-edge advancements, novel designs, and practical applications of meta-surfaces in the THz spectrum. The review begins by exploring the materials employed in meta-surfaces and their crucial role in achieving efficient THz operation. It delves into the realm of polarization diversity, revealing innovative approaches to harnessing the potential of meta-surfaces for polarization control and conversion. A key area of focus is beam-steering technology, with a thorough investigation into beam-steering techniques that have significant implications for enhancing wireless communication, high-resolution imaging, and the internet of things. The paper highlights the potential of these techniques in addressing real-world challenges and advancing THz technology. Furthermore, this review provides an in-depth examination of the innovative antenna designs tailored for THz applications, shedding light on their characteristics and benefits. It also explores the exciting possibilities of THz technology within the medical field, including precise bio sensing and cancer cell detection.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 9","pages":"1-22"},"PeriodicalIF":1.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142377151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Z. Ding;J. Cao;J. Yu;Nasimuddin Nasimuddin;M. Y. Chia;S. Fei;H. Wang
Low-profile miniaturized wideband circularly polarized (CP) monopole and multiple-input-multiple-output (MIMO) antennas using characteristic mode analysis (CMA) are presented. The antennas are constructed with a microstrip feeding line, a slot, and a branch, which positions the transmission line perpendicularly to the branch to achieve CP. The CP characteristic is realized through a characteristic angle (CA) difference of approximately 90° at three mode significance (MS) intersections across four modes. CMA provides both theoretical analysis and design guidance for these antennas. The antennas were fabricated and tested, with dimensions of 0.48λ 0 × 0.48λ 0 × 0.03λ 0 and 0.47λ 0 × 0.47λ 0 × 0.03λ 0 , where λ 0 represents the freespace wavelength. Measurements indicate that the monopole antenna achieves a —10 dB impedance bandwidth (IBW) from 3.2 to 8.4 GHz (89.7% relative bandwidth), a 3 dB axial ratio bandwidth (ARBW) from 3.6 to 5.1 GHz (34.5%), and a peak gain of 6.6 dBic. The MIMO antenna has a —10 dB IBW from 3.1 to 8.2 GHz (90.3%), a 3 dB ARBW from 3.2 to 6 GHz (60.9%), and a peak gain of 5.1 dBic. Both antennas feature a low profile, ultra-wideband IBW, broadband ARBW, and miniaturized design, making them suitable for wideband wireless communication applications.
{"title":"Low-profile miniaturized wideband circularly polarized monopole and MIMO antennas using characteristic mode analysis for wireless communication","authors":"Z. Ding;J. Cao;J. Yu;Nasimuddin Nasimuddin;M. Y. Chia;S. Fei;H. Wang","doi":"10.1029/2024RS008030","DOIUrl":"https://doi.org/10.1029/2024RS008030","url":null,"abstract":"Low-profile miniaturized wideband circularly polarized (CP) monopole and multiple-input-multiple-output (MIMO) antennas using characteristic mode analysis (CMA) are presented. The antennas are constructed with a microstrip feeding line, a slot, and a branch, which positions the transmission line perpendicularly to the branch to achieve CP. The CP characteristic is realized through a characteristic angle (CA) difference of approximately 90° at three mode significance (MS) intersections across four modes. CMA provides both theoretical analysis and design guidance for these antennas. The antennas were fabricated and tested, with dimensions of 0.48λ\u0000<inf>0</inf>\u0000 × 0.48λ\u0000<inf>0</inf>\u0000 × 0.03λ\u0000<inf>0</inf>\u0000 and 0.47λ\u0000<inf>0</inf>\u0000 × 0.47λ\u0000<inf>0</inf>\u0000 × 0.03λ\u0000<inf>0</inf>\u0000, where λ\u0000<inf>0</inf>\u0000 represents the freespace wavelength. Measurements indicate that the monopole antenna achieves a —10 dB impedance bandwidth (IBW) from 3.2 to 8.4 GHz (89.7% relative bandwidth), a 3 dB axial ratio bandwidth (ARBW) from 3.6 to 5.1 GHz (34.5%), and a peak gain of 6.6 dBic. The MIMO antenna has a —10 dB IBW from 3.1 to 8.2 GHz (90.3%), a 3 dB ARBW from 3.2 to 6 GHz (60.9%), and a peak gain of 5.1 dBic. Both antennas feature a low profile, ultra-wideband IBW, broadband ARBW, and miniaturized design, making them suitable for wideband wireless communication applications.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 9","pages":"1-16"},"PeriodicalIF":1.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142376783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Global Navigation Satellite System Ionospheric Seismology investigates the ionospheric response to earthquakes and tsunamis. These events are known to generate Traveling Ionospheric Disturbances (TIDs) that can be detected through GNSS-derived Total Electron Content (TEC) observations. Real-time TID identification provides a method for tsunami detection, improving tsunami early warning systems (TEWS) by extending coverage to open-ocean regions where buoy-based warning systems are impractical. Scalable and automated TID detection is, hence, essential for TEWS augmentation. In this work, we present an innovative approach to perform automatic real-time TID monitoring and detection, using deep learning insights. We utilize Gramian Angular Difference Fields (GADFs), a technique that transforms time-series into images, in combination with Convolutional Neural Networks (CNNs), starting from VARION (Variometric Approach for Real-time Ionosphere Observation) real-time TEC estimates. We select four tsunamigenic earthquakes that occurred in the Pacific Ocean: the 2010 Maule earthquake, the 2011 Tohoku earthquake, the 2012 Haida-Gwaii, the 2015 Illapel earthquake. The first three events are used for model training, whereas the out-of-sample validation is performed on the last one. The presented framework, being perfectly suitable for real-time applications, achieves 91.7% of F1 score and 84.6% of recall, highlighting its potential. Our approach to improve false positive detection, based on the likelihood of a TID at each time step, ensures robust and high performance as the system scales up, integrating more data for model training. This research lays the foundation for incorporating deep learning into real-time GNSS-TEC analysis, offering a joint and substantial contribution to TEWS progression.
全球导航卫星系统电离层地震学研究电离层对地震和海啸的反应。众所周知，这些事件会产生移动电离层扰动（TID），可通过源自全球导航卫星系统的电子总含量（TEC）观测加以探测。实时 TID 识别为海啸探测提供了一种方法，通过将覆盖范围扩大到浮标预警系统不可行的公海地区，改进了海啸预警系统（TEWS）。因此，可扩展的自动 TID 检测对于增强 TEWS 至关重要。在这项工作中，我们提出了一种创新方法，利用深度学习的洞察力进行自动实时 TID 监测和检测。我们利用将时间序列转换为图像的技术--格兰角差场（GADFs），结合卷积神经网络（CNNs），从电离层实时观测变异方法（VARION）的实时 TEC 估计值出发。我们选择了四次发生在太平洋的海啸地震：2010 年毛勒地震、2011 年东北地震、2012 年海达-瓜伊岛地震和 2015 年伊利亚佩尔地震。前三个事件用于模型训练，而样本外验证则在最后一个事件上进行。所提出的框架完全适用于实时应用，F1 得分达到 91.7%，召回率达到 84.6%，彰显了其潜力。我们根据每个时间步的 TID 可能性改进误报检测的方法，确保了系统在扩展时的稳健性和高性能，并整合了更多数据用于模型训练。这项研究为将深度学习纳入实时 GNSS-TEC 分析奠定了基础，为 TEWS 的发展做出了重大贡献。
{"title":"Exploring AI progress in GNSS remote sensing: A deep learning based framework for real-time detection of earthquake and tsunami induced ionospheric perturbations","authors":"Michela Ravanelli;Valentino Constantinou;Hamlin Liu;Jacob Bortnik","doi":"10.1029/2024RS008016","DOIUrl":"https://doi.org/10.1029/2024RS008016","url":null,"abstract":"Global Navigation Satellite System Ionospheric Seismology investigates the ionospheric response to earthquakes and tsunamis. These events are known to generate Traveling Ionospheric Disturbances (TIDs) that can be detected through GNSS-derived Total Electron Content (TEC) observations. Real-time TID identification provides a method for tsunami detection, improving tsunami early warning systems (TEWS) by extending coverage to open-ocean regions where buoy-based warning systems are impractical. Scalable and automated TID detection is, hence, essential for TEWS augmentation. In this work, we present an innovative approach to perform automatic real-time TID monitoring and detection, using deep learning insights. We utilize Gramian Angular Difference Fields (GADFs), a technique that transforms time-series into images, in combination with Convolutional Neural Networks (CNNs), starting from VARION (Variometric Approach for Real-time Ionosphere Observation) real-time TEC estimates. We select four tsunamigenic earthquakes that occurred in the Pacific Ocean: the 2010 Maule earthquake, the 2011 Tohoku earthquake, the 2012 Haida-Gwaii, the 2015 Illapel earthquake. The first three events are used for model training, whereas the out-of-sample validation is performed on the last one. The presented framework, being perfectly suitable for real-time applications, achieves 91.7% of F1 score and 84.6% of recall, highlighting its potential. Our approach to improve false positive detection, based on the likelihood of a TID at each time step, ensures robust and high performance as the system scales up, integrating more data for model training. This research lays the foundation for incorporating deep learning into real-time GNSS-TEC analysis, offering a joint and substantial contribution to TEWS progression.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 9","pages":"1-18"},"PeriodicalIF":1.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142376782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The measurement of soil moisture is important for many practical applications. We describe the theoretical design of a simple, noncontact, electromagnetic probe that complements many existing soil moisture measurement techniques. The approach uses a low-frequency (i.e., 50–150 MHz) antenna operating in proximity of the soil. The presence of the soil affects the antenna input impedance, which in turn depends on the distance between the soil and antenna and the complex dielectric constant of the soil. The latter strongly depends on the soil wetness, which suggests that bulk soil moisture integrated over a depth of roughly 1 m can be inferred from antenna impedance measurements. This is in contrast with many current higher-frequency techniques that penetrate only a few centimeters into the soil and provide only near-surface values of soil wetness. Our work suggests that under ideal conditions bulk soil moisture can be mapped with an accuracy on the order of 1% over horizontal scales spanning a few tens of meters to a few kilometers using simple low-frequency antennas.
{"title":"A simple noncontact soil moisture probe for weather and climate applications","authors":"A. G. Voronovich;P. E. Johnston;R. J. Lataitis","doi":"10.1029/2023RS007857","DOIUrl":"https://doi.org/10.1029/2023RS007857","url":null,"abstract":"The measurement of soil moisture is important for many practical applications. We describe the theoretical design of a simple, noncontact, electromagnetic probe that complements many existing soil moisture measurement techniques. The approach uses a low-frequency (i.e., 50–150 MHz) antenna operating in proximity of the soil. The presence of the soil affects the antenna input impedance, which in turn depends on the distance between the soil and antenna and the complex dielectric constant of the soil. The latter strongly depends on the soil wetness, which suggests that bulk soil moisture integrated over a depth of roughly 1 m can be inferred from antenna impedance measurements. This is in contrast with many current higher-frequency techniques that penetrate only a few centimeters into the soil and provide only near-surface values of soil wetness. Our work suggests that under ideal conditions bulk soil moisture can be mapped with an accuracy on the order of 1% over horizontal scales spanning a few tens of meters to a few kilometers using simple low-frequency antennas.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 9","pages":"1-11"},"PeriodicalIF":1.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142376844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Detection of earthquake precursors has long been a controversial issue with regard to its possibility and realizability. Here we present the detection of electromagnetic anomalous signals before large earthquakes using an observation network of very high frequency radio wave receivers close to major tectonic lines in Japan. The receivers are equipped with specifically designed narrowband filters to suppress noises and to detect extremely weak signals. We detected different types of electromagnetic anomalies before earthquakes around mountainous and coastal regions, where presence of electric charges is anticipated on the surface located in the middle of the radio wave paths near major tectonic lines in Japan. We use numerical electromagnetic wave analysis to show that when electric charges are present on a ground surface as a consequence of tectonic activity, the surface charges interact strongly with radio waves and eventually cause strong diffraction of the radio waves. The analysis was performed using the three-dimensional finite-difference time-domain method with digital elevation models of the actual geographical landforms on a massively parallel supercomputer. The results confirm the consistent mechanisms of the electromagnetic precursors, which explains the anomalous electromagnetic signals observed by the authors before large earthquakes.
{"title":"Observation and analysis of anomalous terrestrial diffraction as a mechanism of electromagnetic precursors of earthquakes","authors":"Masafumi Fujii","doi":"10.1029/2023RS007888","DOIUrl":"https://doi.org/10.1029/2023RS007888","url":null,"abstract":"Detection of earthquake precursors has long been a controversial issue with regard to its possibility and realizability. Here we present the detection of electromagnetic anomalous signals before large earthquakes using an observation network of very high frequency radio wave receivers close to major tectonic lines in Japan. The receivers are equipped with specifically designed narrowband filters to suppress noises and to detect extremely weak signals. We detected different types of electromagnetic anomalies before earthquakes around mountainous and coastal regions, where presence of electric charges is anticipated on the surface located in the middle of the radio wave paths near major tectonic lines in Japan. We use numerical electromagnetic wave analysis to show that when electric charges are present on a ground surface as a consequence of tectonic activity, the surface charges interact strongly with radio waves and eventually cause strong diffraction of the radio waves. The analysis was performed using the three-dimensional finite-difference time-domain method with digital elevation models of the actual geographical landforms on a massively parallel supercomputer. The results confirm the consistent mechanisms of the electromagnetic precursors, which explains the anomalous electromagnetic signals observed by the authors before large earthquakes.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 9","pages":"1-18"},"PeriodicalIF":1.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142377050","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The 5G new era implements standalone satellite communications that support wireless networking systems for future mobile communications by locating multiple satellites in low Earth orbit to provide global coverage of the entire Earth's surface. In this research, a newly found model of a satellite onboard transmitter using a uniform circular array multiple-input multiple-output antenna was designed to operate at a carrier frequency of 12 GHz and derived theoretical equations compared to the real-time scenario. The integration of spread spectrum with multiple-input multiple-output antenna provides an advantage for higher capacity. It has a higher percentage of gain amplification on improving the transmission of electromagnetic power to meet the bandwidth requirement of center operating frequency, and this can transmit over a bandwidth of 1.28 GHz. The proposed satellite onboard transmitter model design aims to minimize the components, increase the speed of operations for higher bandwidth, and transmit large amounts of information to a large group of users. The transmitter can operate for the speed of 1.28 Gbps using pseudo-random code, direct-sequence spread spectrum, quadrature phase shift keying modulation, bandwidth separated in bands for 64 symbols using 128 Chebyshev-type bandpass filter for transmission using 128-element uniform circular array multiple-input multiple-output antenna. The satellite transmitter antenna produces a maximum gain of 14.526 dBi, and a maximum directivity of 17.986 dBi, and the efficiency at 12 GHz is 45.1% for the radiated power at 0.93 mW. This satellite transmitter will interconnect 5G wireless networks for the application of mobile communications complement terrestrial-dependent networks.
{"title":"Satellite onboard transmitter design with spread spectrum MIMO antenna for 5G wireless networks","authors":"Ravandran Muttiah","doi":"10.1029/2024RS007958","DOIUrl":"https://doi.org/10.1029/2024RS007958","url":null,"abstract":"The 5G new era implements standalone satellite communications that support wireless networking systems for future mobile communications by locating multiple satellites in low Earth orbit to provide global coverage of the entire Earth's surface. In this research, a newly found model of a satellite onboard transmitter using a uniform circular array multiple-input multiple-output antenna was designed to operate at a carrier frequency of 12 GHz and derived theoretical equations compared to the real-time scenario. The integration of spread spectrum with multiple-input multiple-output antenna provides an advantage for higher capacity. It has a higher percentage of gain amplification on improving the transmission of electromagnetic power to meet the bandwidth requirement of center operating frequency, and this can transmit over a bandwidth of 1.28 GHz. The proposed satellite onboard transmitter model design aims to minimize the components, increase the speed of operations for higher bandwidth, and transmit large amounts of information to a large group of users. The transmitter can operate for the speed of 1.28 Gbps using pseudo-random code, direct-sequence spread spectrum, quadrature phase shift keying modulation, bandwidth separated in bands for 64 symbols using 128 Chebyshev-type bandpass filter for transmission using 128-element uniform circular array multiple-input multiple-output antenna. The satellite transmitter antenna produces a maximum gain of 14.526 dBi, and a maximum directivity of 17.986 dBi, and the efficiency at 12 GHz is 45.1% for the radiated power at 0.93 mW. This satellite transmitter will interconnect 5G wireless networks for the application of mobile communications complement terrestrial-dependent networks.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 9","pages":"1-20"},"PeriodicalIF":1.6,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142377113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study reports coordinated observation of ionospheric irregularities from VHF Radar, GPS and IRNSS (Indian Regional Navigation Satellite System), from regions near the northern crest of the EIA (Equatorial Ionization Anomaly), which has not been explored earlier. Efforts have been made to study the signal-in-space environment for concurrent detection of ionospheric irregularities over a range of radio frequency, starting from 53 MHz of the Radar, to L-band of GPS at 1,575.42 MHz and S band signal of IRNSS at 2,492.5 MHz. The radar is operational at Ionosphere Field Station, Haringhata (geographic latitude 22.93°N; geographic longitude 88.5I°E; magnetic dip angle 36.2°N) of University of Calcutta. The GPS and IRNSS data are recorded at Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 36°N), separated from Haringhata by 50 km. The spatial as well as temporal variations of irregularities affecting different radio frequencies have been presented. Coordinated observations have been made during period of March-April 2023. Results of the study reveal the common zone of impact of the different radio frequency links spanning from 53 to 2,592.5 MHz and was identified within I6°–25°N, 85°–90°E. During coordinated observations made over several days, irregularity structures have been observed with radar, having backscatter SNR (Signal to Noise ratio) intensity within — 5 to 15 dB. During this time, while intense L band scintillation was recorded on multiple satellites of GPS, scintillation recorded at S band signal was moderate to intense.
本研究报告了从甚高频雷达、全球定位系统和 IRNSS（印度区域导航卫星系 统）对电离层不规则现象进行的协调观测，观测地点位于赤道电离异常北部峰顶 附近的区域，此前未对该区域进行过探索。已努力研究空间信号环境，以便同时探测从雷达 53 兆赫到全球定位系统 L 波段 1,575.42 兆赫和 IRNSS S 波段 2,492.5 兆赫的无线电频率范围内的电离层不规则情况。雷达在加尔各答大学哈林哈塔电离层场站（地理纬度 22.93°N；地理经度 88.5I°E；磁倾角 36.2°N）运行。全球定位系统和 IRNSS 数据记录在加尔各答（地理纬度 22.58°N，88.38°E；磁倾角 36°N），与哈林哈塔相距 50 公里。介绍了影响不同无线电频率的不规则现象的空间和时间变化。在 2023 年 3 月至 4 月期间进行了协调观测。研究结果表明，不同无线电频率链路的共同影响区跨越 53 至 2,592.5 兆赫，位于北纬 I6°-25°，东经 85°-90°。在几天的协调观测中，雷达观测到了不规则结构，其反向散射 SNR（信噪比）强度在 - 5 至 15 dB 之间。在此期间，虽然全球定位系统的多颗卫星记录到强烈的 L 波段闪烁，但 S 波段信号记录到的闪烁强度为中等至强烈。
{"title":"Low latitude ionospheric irregularity observations across a wide frequency spectrum from VHF to S-band in the Indian longitudes","authors":"A. Paul;A. Das;T. Biswas;T. Das;P. Nandakumar","doi":"10.1029/2023RS007928","DOIUrl":"https://doi.org/10.1029/2023RS007928","url":null,"abstract":"This study reports coordinated observation of ionospheric irregularities from VHF Radar, GPS and IRNSS (Indian Regional Navigation Satellite System), from regions near the northern crest of the EIA (Equatorial Ionization Anomaly), which has not been explored earlier. Efforts have been made to study the signal-in-space environment for concurrent detection of ionospheric irregularities over a range of radio frequency, starting from 53 MHz of the Radar, to L-band of GPS at 1,575.42 MHz and S band signal of IRNSS at 2,492.5 MHz. The radar is operational at Ionosphere Field Station, Haringhata (geographic latitude 22.93°N; geographic longitude 88.5I°E; magnetic dip angle 36.2°N) of University of Calcutta. The GPS and IRNSS data are recorded at Calcutta (22.58°N, 88.38°E geographic; magnetic dip: 36°N), separated from Haringhata by 50 km. The spatial as well as temporal variations of irregularities affecting different radio frequencies have been presented. Coordinated observations have been made during period of March-April 2023. Results of the study reveal the common zone of impact of the different radio frequency links spanning from 53 to 2,592.5 MHz and was identified within I6°–25°N, 85°–90°E. During coordinated observations made over several days, irregularity structures have been observed with radar, having backscatter SNR (Signal to Noise ratio) intensity within — 5 to 15 dB. During this time, while intense L band scintillation was recorded on multiple satellites of GPS, scintillation recorded at S band signal was moderate to intense.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 8","pages":"1-9"},"PeriodicalIF":1.6,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jorge L. Chau;Facundo L. Poblet;Hanli Liu;Alan Liu;Njål Gulbrandsen;Christoph Jacobi;Rodolfo R. Rodriguez;Danny Scipion;Masaki Tsutsumi
Utilizing multistatic specular meteor radar (MSMR) observations, this study delves into global aspects of wind perturbations in the mesosphere and lower thermosphere (MLT) from the unprecedented 2022 eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) submarine volcano. The combination of MSMR observations from different viewing angles over South America and Europe, and the decomposition of the horizontal wind in components along and transversal to the HTHH eruption's epicenter direction allow an unambiguous detection and identification of MLT perturbations related to the eruption. The performance of this decomposition is evaluated using Whole Atmosphere Community Climate Model with thermosphere/ ionosphere extension (WACCM-X) simulations of the event. The approach shows that indeed the HTHH eruption signals are clearly identified, and other signals can be easily discarded. The winds in this decomposition display dominant Eastward soliton-like perturbations observed as far as 25,000 km from HTHH, and propagating at 242 m/s. A weaker perturbation observed only over Europe propagates faster (but slower than 300 m/s) in the Westward direction. These results suggest that we might be observing the so-called Pekeris mode, also consistent with the L 1 pseudomode, reproduced by WACCM-X simulations at MLT altitudes. They also rule out the previous hypothesis connecting the observations in South America to the Tsunami associated with the eruption because these perturbations are observed over Europe as well. Despite the progress, the L 0 pseudomode in the MLT reproduced by WACCM-X remains elusive to observations.
{"title":"Mesosphere and lower thermosphere wind perturbations due to the 2022 Hunga Tonga-Hunga Ha'apai eruption as observed by multistatic specular meteor radars","authors":"Jorge L. Chau;Facundo L. Poblet;Hanli Liu;Alan Liu;Njål Gulbrandsen;Christoph Jacobi;Rodolfo R. Rodriguez;Danny Scipion;Masaki Tsutsumi","doi":"10.1029/2024RS008013","DOIUrl":"https://doi.org/10.1029/2024RS008013","url":null,"abstract":"Utilizing multistatic specular meteor radar (MSMR) observations, this study delves into global aspects of wind perturbations in the mesosphere and lower thermosphere (MLT) from the unprecedented 2022 eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) submarine volcano. The combination of MSMR observations from different viewing angles over South America and Europe, and the decomposition of the horizontal wind in components along and transversal to the HTHH eruption's epicenter direction allow an unambiguous detection and identification of MLT perturbations related to the eruption. The performance of this decomposition is evaluated using Whole Atmosphere Community Climate Model with thermosphere/ ionosphere extension (WACCM-X) simulations of the event. The approach shows that indeed the HTHH eruption signals are clearly identified, and other signals can be easily discarded. The winds in this decomposition display dominant Eastward soliton-like perturbations observed as far as 25,000 km from HTHH, and propagating at 242 m/s. A weaker perturbation observed only over Europe propagates faster (but slower than 300 m/s) in the Westward direction. These results suggest that we might be observing the so-called Pekeris mode, also consistent with the L\u0000<inf>1</inf>\u0000 pseudomode, reproduced by WACCM-X simulations at MLT altitudes. They also rule out the previous hypothesis connecting the observations in South America to the Tsunami associated with the eruption because these perturbations are observed over Europe as well. Despite the progress, the L\u0000<inf>0</inf>\u0000 pseudomode in the MLT reproduced by WACCM-X remains elusive to observations.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 8","pages":"1-14"},"PeriodicalIF":1.6,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
a rectenna designed for wireless power transfer at 900 MHz focuses on conjugate impedance matching and image impedance matching for improved efficiency. To do them, a voltage doubler rectifier circuit (VD) and a planar monopole antenna (PMA) were engineered with the same pure resistance value and integrated into the rectenna. The input impedance of the VD with 30 Ω load resistance indicated a pure resistance of approximately 73 Ω. This value closely matches the input impedance of a dipole antenna operating as a pure resistor. Since the prototype rectifier circuit is unbalanced, the authors constructed a PMA, an unbalanced antenna similar to a dipole antenna, on a double-sided circuit board. In this setup, a microstrip line was created by extending the radiating element, achieving the impedance matchings. Measurements indicated a voltage standing wave ratio of approximately 1.03. A rectenna efficiency of 37.4% was observed for a transmission distance of 50 cm. The rectification efficiency of the VD is nearly 0% when the input power is less than — 20 dBm, and the received power of the PMA is less than — 20 dBm when the transmission distance is 60 cm or more. It is predicted that the rectenna efficiency will be 0% when the transmission distance is 60 cm or more. However, the rectenna efficiency was 24.6% when the transmission distance was 60 cm. This over 20% improvement is due to the connection between the PMA and the VD using pure resistance.
{"title":"A prototype of a 900 MHz band integrated rectenna by using a planar monopole antenna with feeder","authors":"N. Nakashima;T. Sumiyoshi","doi":"10.1029/2024RS008022","DOIUrl":"https://doi.org/10.1029/2024RS008022","url":null,"abstract":"a rectenna designed for wireless power transfer at 900 MHz focuses on conjugate impedance matching and image impedance matching for improved efficiency. To do them, a voltage doubler rectifier circuit (VD) and a planar monopole antenna (PMA) were engineered with the same pure resistance value and integrated into the rectenna. The input impedance of the VD with 30 Ω load resistance indicated a pure resistance of approximately 73 Ω. This value closely matches the input impedance of a dipole antenna operating as a pure resistor. Since the prototype rectifier circuit is unbalanced, the authors constructed a PMA, an unbalanced antenna similar to a dipole antenna, on a double-sided circuit board. In this setup, a microstrip line was created by extending the radiating element, achieving the impedance matchings. Measurements indicated a voltage standing wave ratio of approximately 1.03. A rectenna efficiency of 37.4% was observed for a transmission distance of 50 cm. The rectification efficiency of the VD is nearly 0% when the input power is less than — 20 dBm, and the received power of the PMA is less than — 20 dBm when the transmission distance is 60 cm or more. It is predicted that the rectenna efficiency will be 0% when the transmission distance is 60 cm or more. However, the rectenna efficiency was 24.6% when the transmission distance was 60 cm. This over 20% improvement is due to the connection between the PMA and the VD using pure resistance.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 8","pages":"1-12"},"PeriodicalIF":1.6,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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