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}
Sukanth Karapakula;Christiaan Brinkerink;Antonio Vecchio;Hamid R. Pourshaghaghi;Peter Dolron;Roel Jordans;Eric Bertels;Gerard Aalbers;Mark Ruiter;Albert J. Boonstra;Mark Bentum;David Prinsloo;Michel Arts;Jeanette Bast;Sieds Damstra;Albert van Duin;Nico Ebbendorf;Hans van der Marel;Juergen Morawietz;Roel Witvers;Wietse Poiesz;Rico van Dongen;Baptiste Cecconi;Philippe Zarka;Moustapha Dekkali;Linjie Chen;Mingyuan Wang;Mo Zhang;Maohai Huang;Yihua Yan;Liang Dong;Baolin Tan;Lihua Zhang;Liang Xiong;Ji Sun;Hongbo Zhang;Jinsong Ping;Marc Klein Wolt;Heino Falcke
The Netherlands-China Low-Frequency Explorer (NCLE) (Boonstra et al., 2017, https://www. ursi.org/proceedings/procGA17/papers/Paper_J19-2(1603).pdf; Chen et al., 2020, https://ui.adsabs.harvard.edu/abs/2020AAS...23610203C/abstract) is a radio instrument for astrophysical studies in the low-frequency range (80 kHz-80 MHz). As a technology demonstrator, NCLE shall inform the design of future radio receivers that aim at low-frequency radio astronomy. NCLE can make observations at very high spectral resolution (<1 kHz) and generate radio sky maps at an angular resolution of ≈1.5 radians. NCLE uses three monopole antennas, each 5 m long, and three identical analog signal chains to process the signal from each antenna. A single digital receiver samples the signal and calculates the auto-correlated and cross-correlated spectra. The instrument's analog and digital signal chains are extensively configurable. They can be fine-tuned to produce broadband spectra covering the instrument's complete operating frequency range or sub-bands. NCLE was developed within a veryshort timescale of 2 years, and currently, it is on board Queqiao, the relay spacecraft of the Chang'e-4 mission, in a halo orbit around the Earth-Moon L2 point. This paper outlines the science cases, instrument architecture with focus on the signal chain, and discusses the laboratory measurements during the pre-launch phase.
{"title":"Architecture design and ground performance of Netherlands-China low-frequency explorer","authors":"Sukanth Karapakula;Christiaan Brinkerink;Antonio Vecchio;Hamid R. Pourshaghaghi;Peter Dolron;Roel Jordans;Eric Bertels;Gerard Aalbers;Mark Ruiter;Albert J. Boonstra;Mark Bentum;David Prinsloo;Michel Arts;Jeanette Bast;Sieds Damstra;Albert van Duin;Nico Ebbendorf;Hans van der Marel;Juergen Morawietz;Roel Witvers;Wietse Poiesz;Rico van Dongen;Baptiste Cecconi;Philippe Zarka;Moustapha Dekkali;Linjie Chen;Mingyuan Wang;Mo Zhang;Maohai Huang;Yihua Yan;Liang Dong;Baolin Tan;Lihua Zhang;Liang Xiong;Ji Sun;Hongbo Zhang;Jinsong Ping;Marc Klein Wolt;Heino Falcke","doi":"10.1029/2023RS007906","DOIUrl":"https://doi.org/10.1029/2023RS007906","url":null,"abstract":"The Netherlands-China Low-Frequency Explorer (NCLE) (Boonstra et al., 2017, https://www. ursi.org/proceedings/procGA17/papers/Paper_J19-2(1603).pdf; Chen et al., 2020, https://ui.adsabs.harvard.edu/abs/2020AAS...23610203C/abstract) is a radio instrument for astrophysical studies in the low-frequency range (80 kHz-80 MHz). As a technology demonstrator, NCLE shall inform the design of future radio receivers that aim at low-frequency radio astronomy. NCLE can make observations at very high spectral resolution (<1 kHz) and generate radio sky maps at an angular resolution of ≈1.5 radians. NCLE uses three monopole antennas, each 5 m long, and three identical analog signal chains to process the signal from each antenna. A single digital receiver samples the signal and calculates the auto-correlated and cross-correlated spectra. The instrument's analog and digital signal chains are extensively configurable. They can be fine-tuned to produce broadband spectra covering the instrument's complete operating frequency range or sub-bands. NCLE was developed within a veryshort timescale of 2 years, and currently, it is on board Queqiao, the relay spacecraft of the Chang'e-4 mission, in a halo orbit around the Earth-Moon L2 point. This paper outlines the science cases, instrument architecture with focus on the signal chain, and discusses the laboratory measurements during the pre-launch phase.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 8","pages":"1-39"},"PeriodicalIF":1.6,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130281","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}
In this study, a wideband circularly polarized (CP) H-plane horn antenna based on Gap Waveguide (GW) technology in K-band is presented. The proposed antenna consists of two unconnected metal planes. To produce broadband CP radiation, two main methods are utilized. First, two antipodal tapered plates (ATPs) are added in front of the horn. The ATPs are carefully designed for dissimilar polarization orientations. By this technique, the orthogonal electric fields can be prepared. Then, by embedding three metal square pins near the center of the aperture in both inner plates, the impedance bandwidth (BW) and BW of CP radiation of the proposed horn is entirely improved. Its BW for target |S 11 | < —10 dB is 18—28 GHz. Also, the peak gain fluctuates between 11.5 and 13 dB. This antenna can provide a 3 dB polarization axial-ratio BW of about 28.5% (20–26 GHz). Total radiation efficiency is higher than 94%. To verify the design, the proposed structure is manufactured and tested. The proposed horn antenna result has an appropriate agreement between measurement and simulation. Its miniaturized dimensions, easy and cheap fabrication, and broadband CP capability make it a proper volunteer for broadband communication systems.
本研究提出了一种基于间隙波导（GW）技术的 K 波段宽带圆极化（CP）H 平面喇叭天线。该天线由两个未连接的金属平面组成。为了产生宽带 CP 辐射，主要采用了两种方法。首先，在喇叭前面增加了两个对顶锥形板（ATP）。ATP 经过精心设计，具有不同的极化方向。通过这种技术，可以制备正交电场。然后，通过在两块内板上靠近孔径中心的位置嵌入三个金属方针，完全改善了拟建喇叭的阻抗带宽（BW）和 CP 辐射带宽。当目标 |S11| < -10 dB 时，其 BW 为 18-28 GHz。此外，峰值增益在 11.5 和 13 dB 之间波动。该天线可提供约 28.5% （20-26 GHz）的 3 dB 极化轴向比频带宽度。总辐射效率高于 94%。为了验证设计，对所提出的结构进行了制造和测试。所提议的喇叭天线的测量结果与模拟结果之间具有适当的一致性。其微型化的尺寸、简便廉价的制造工艺和宽带 CP 能力使其成为宽带通信系统的理想选择。
{"title":"Miniaturized, broadband, circular polarized horn antenna with Groove gap waveguide technology","authors":"Amir Hossein Haghparast;Pejman Rezaei","doi":"10.1029/2024RS007965","DOIUrl":"https://doi.org/10.1029/2024RS007965","url":null,"abstract":"In this study, a wideband circularly polarized (CP) H-plane horn antenna based on Gap Waveguide (GW) technology in K-band is presented. The proposed antenna consists of two unconnected metal planes. To produce broadband CP radiation, two main methods are utilized. First, two antipodal tapered plates (ATPs) are added in front of the horn. The ATPs are carefully designed for dissimilar polarization orientations. By this technique, the orthogonal electric fields can be prepared. Then, by embedding three metal square pins near the center of the aperture in both inner plates, the impedance bandwidth (BW) and BW of CP radiation of the proposed horn is entirely improved. Its BW for target |S\u0000<inf>11</inf>\u0000| < —10 dB is 18—28 GHz. Also, the peak gain fluctuates between 11.5 and 13 dB. This antenna can provide a 3 dB polarization axial-ratio BW of about 28.5% (20–26 GHz). Total radiation efficiency is higher than 94%. To verify the design, the proposed structure is manufactured and tested. The proposed horn antenna result has an appropriate agreement between measurement and simulation. Its miniaturized dimensions, easy and cheap fabrication, and broadband CP capability make it a proper volunteer for broadband communication systems.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 8","pages":"1-10"},"PeriodicalIF":1.6,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130306","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}
Jia Tan;Haidong Xie;Xiaoying Zhang;Nan Ji;Haihua Liao;ZuGuo Yu;Xueshuang Xiang;Naijin Liu
Deep learning is applied to many complex tasks in the field of wireless communication, such as modulation recognition of spectrum waveforms, because of its convenience and efficiency. This leads to the problem of a malicious third party using a deep learning model to easily recognize the modulation format of the transmitted waveform. Some existing works address this problem directly using the concept of adversarial examples in the computer vision field without fully considering the characteristics of the waveform transmission in the physical world. Therefore, we propose two low-interception waveforms (LIWs) generation methods, the LIW and ULIW algorithms, which can reduce the probability of the modulation being recognized by a third party without affecting the reliable communication of the friendly party. Among them, ULIW improves LIW algorithm by simulating channel noise during training cycle, and substantially reduces the perturbation magnitude while maintaining low interception accuracy. Our LIW and ULIW exhibit significant low-interception performance in both numerical simulations and hardware experiments.
{"title":"Low-interception waveforms: To prevent the recognition of spectrum waveform modulation via adversarial examples","authors":"Jia Tan;Haidong Xie;Xiaoying Zhang;Nan Ji;Haihua Liao;ZuGuo Yu;Xueshuang Xiang;Naijin Liu","doi":"10.1029/2022RS007486","DOIUrl":"https://doi.org/10.1029/2022RS007486","url":null,"abstract":"Deep learning is applied to many complex tasks in the field of wireless communication, such as modulation recognition of spectrum waveforms, because of its convenience and efficiency. This leads to the problem of a malicious third party using a deep learning model to easily recognize the modulation format of the transmitted waveform. Some existing works address this problem directly using the concept of adversarial examples in the computer vision field without fully considering the characteristics of the waveform transmission in the physical world. Therefore, we propose two low-interception waveforms (LIWs) generation methods, the LIW and ULIW algorithms, which can reduce the probability of the modulation being recognized by a third party without affecting the reliable communication of the friendly party. Among them, ULIW improves LIW algorithm by simulating channel noise during training cycle, and substantially reduces the perturbation magnitude while maintaining low interception accuracy. Our LIW and ULIW exhibit significant low-interception performance in both numerical simulations and hardware experiments.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 8","pages":"1-13"},"PeriodicalIF":1.6,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142130260","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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