a new solution for the analysis of slitted parallel-plate waveguide is proposed using the method of Kobayashi Potential (KP). The interior and exterior problems are studied for the TE and TM polarizations. Simplified forms of Weber-Schafheitlin (WS) integrals are utilized for problem formulation. The Fourier function space is exploited to construct the governing linear system of equations. A simple strategy is suggested for the evaluation of the required integrals. Numerical results are validated through convergence analysis and available reports based on the Moment Method (MM). It is shown that the KP is superior to the conventional MM in the sense of tracking edge singularities, especially when the radiation problem is of interest.
利用小林势（KP）方法，提出了分析狭缝平行板波导的新方案。研究了 TE 和 TM 偏振的内部和外部问题。利用韦伯-沙菲特林（WS）积分的简化形式进行问题表述。利用傅立叶函数空间来构建线性方程组。为评估所需的积分提出了一个简单的策略。通过收敛分析和基于矩量法（MM）的可用报告验证了数值结果。结果表明，KP 在跟踪边缘奇异性方面优于传统的 MM，尤其是当辐射问题令人关注时。
{"title":"Analysis of slitted parallel-plate waveguides using the method of kobayashi potential","authors":"B. Honarbakhsh","doi":"10.1029/2024RS007990","DOIUrl":"https://doi.org/10.1029/2024RS007990","url":null,"abstract":"a new solution for the analysis of slitted parallel-plate waveguide is proposed using the method of Kobayashi Potential (KP). The interior and exterior problems are studied for the TE and TM polarizations. Simplified forms of Weber-Schafheitlin (WS) integrals are utilized for problem formulation. The Fourier function space is exploited to construct the governing linear system of equations. A simple strategy is suggested for the evaluation of the required integrals. Numerical results are validated through convergence analysis and available reports based on the Moment Method (MM). It is shown that the KP is superior to the conventional MM in the sense of tracking edge singularities, especially when the radiation problem is of interest.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-22"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595847","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 paper, a series of numerical simulations are conducted for various 2D and 3D configurations to demonstrate the performance of the Time Reversal Multiple Signal Classification (TR-MUSIC) method. The results reveal the excellent performance of TR-MUSIC, taking into account the effects of noise, soil types (both homogeneous and layered), and their electrical parameters, as well as different types of targets (varying in number, size, shape, and location). Additionally, unlike other electromagnetic TR-based techniques, TR-MUSIC offers very high resolution (on the order of 1/10 or higher) with a reasonable number of sensors, enabling the detection of multiple closely spaced targets. In TR-based methods, reflections from the object(s) or landmine(s) are crucial and are determined by the difference between the constitutive parameters (e.g., permittivity, permeability, and conductivity) of the landmine(s) and their surrounding medium. Therefore, TR-based approaches, similar to conventional GPR-based approaches, are suitable for detecting objects or landmines with significant differences in constitutive parameters compared to their immersion medium. This research primarily focuses on metallic objects or landmines.
{"title":"Landmine detection using electromagnetic time reversal-based methods: 2. performance analysis of TR-MUSIC","authors":"Hamidreza Karami;André Koch;Carlos Romero;Marcos Rubinstein;Farhad Rachidi","doi":"10.1029/2024RS007972","DOIUrl":"https://doi.org/10.1029/2024RS007972","url":null,"abstract":"In this paper, a series of numerical simulations are conducted for various 2D and 3D configurations to demonstrate the performance of the Time Reversal Multiple Signal Classification (TR-MUSIC) method. The results reveal the excellent performance of TR-MUSIC, taking into account the effects of noise, soil types (both homogeneous and layered), and their electrical parameters, as well as different types of targets (varying in number, size, shape, and location). Additionally, unlike other electromagnetic TR-based techniques, TR-MUSIC offers very high resolution (on the order of 1/10 or higher) with a reasonable number of sensors, enabling the detection of multiple closely spaced targets. In TR-based methods, reflections from the object(s) or landmine(s) are crucial and are determined by the difference between the constitutive parameters (e.g., permittivity, permeability, and conductivity) of the landmine(s) and their surrounding medium. Therefore, TR-based approaches, similar to conventional GPR-based approaches, are suitable for detecting objects or landmines with significant differences in constitutive parameters compared to their immersion medium. This research primarily focuses on metallic objects or landmines.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-14"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595780","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}
Ying Han;Qingjie Liu;Jianping Huang;Zhong Li;Rui Yan;Jing Yuan;Xuhui Shen;Lili Xing;Guoli Pang
Constant Frequency Electromagnetic Waves (CFEWs) refer to electromagnetic waves with a constant frequency. Man-made CFEWs are mainly used in wireless communication, scientific research, global navigation and positioning systems, and military radar. CFEWs exhibit horizontal line characteristics higher than the background on spectrograms. In this study, we focus on Very Low Frequency (VLF) waveform data and power spectral data collected by the China Seismo-Electromagnetic Satellite (CSES) Electromagnetic Field Detector (EFD). We utilize deep learning techniques to construct an improved Vgg16-Unet model for automatically detecting horizontal lines on time-frequency spectrogram and extracting their frequencies. First, we transform waveform data into time-frequency spectrogram with a duration of 2 s using Short-Time Fourier Transform. Then, we manually label horizontal lines on the time-frequency spectrogram using the Labelme tool to establish the dataset. Next, we establish and improve the Vgg16-Unet deep learning model. Finally, we train and test the model using the dataset. Statistical experimental results show that the error rate of line detection is 0, indicating high reliability of the model, with fewer parameters and fast computation speed suitable for practical applications. Not only do we detect lines through the model, but we also obtain their frequencies. Additionally, in batch-generated power spectrogram of CFEWs, we discover some unstable phenomena such as frequency shifts and fluctuations, which contribute to understanding the propagation mechanism of CFEWs in the ionosphere and improving the accuracy of related systems.
{"title":"Automatic extraction of VLF constant-frequency electromagnetic wave frequency based on an improved Vgg16-Unet","authors":"Ying Han;Qingjie Liu;Jianping Huang;Zhong Li;Rui Yan;Jing Yuan;Xuhui Shen;Lili Xing;Guoli Pang","doi":"10.1029/2024RS008019","DOIUrl":"https://doi.org/10.1029/2024RS008019","url":null,"abstract":"Constant Frequency Electromagnetic Waves (CFEWs) refer to electromagnetic waves with a constant frequency. Man-made CFEWs are mainly used in wireless communication, scientific research, global navigation and positioning systems, and military radar. CFEWs exhibit horizontal line characteristics higher than the background on spectrograms. In this study, we focus on Very Low Frequency (VLF) waveform data and power spectral data collected by the China Seismo-Electromagnetic Satellite (CSES) Electromagnetic Field Detector (EFD). We utilize deep learning techniques to construct an improved Vgg16-Unet model for automatically detecting horizontal lines on time-frequency spectrogram and extracting their frequencies. First, we transform waveform data into time-frequency spectrogram with a duration of 2 s using Short-Time Fourier Transform. Then, we manually label horizontal lines on the time-frequency spectrogram using the Labelme tool to establish the dataset. Next, we establish and improve the Vgg16-Unet deep learning model. Finally, we train and test the model using the dataset. Statistical experimental results show that the error rate of line detection is 0, indicating high reliability of the model, with fewer parameters and fast computation speed suitable for practical applications. Not only do we detect lines through the model, but we also obtain their frequencies. Additionally, in batch-generated power spectrogram of CFEWs, we discover some unstable phenomena such as frequency shifts and fluctuations, which contribute to understanding the propagation mechanism of CFEWs in the ionosphere and improving the accuracy of related systems.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-14"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595787","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 paper presents a dual-polarized cavity-backed antenna designed for mm-wave applications, featuring simple feeding structures with a high-isolation for 60 GHz compact AiP applications. The dual-polarization design relies on two separate feed ports that excite two orthogonal modes within the same resonant cavity, achieving very high port isolation of up to 40 dB over the entire band. We conducted a detail analysis of the antenna, including its working principles and parametric studies. For verification, we fabricated an antenna test kit using standard printed process on substrates and measured the kit from the back-side of a GSG probing platform. The proposed antenna demonstrates a wide impedance bandwidth, stable radiation patterns, very low cross-polarization levels, and a high radiation efficiency. The co-located cavity-backed design ensures the compactness and facilitates easy integration with ICs in a very small AiP module. These features make the proposed antenna highly suitable for 60 GHz AiP applications, such as high-data-rate wireless communication and mmW polarimetric radar systems.
{"title":"Realizing orthogonal modes in compact cavity-backed dual-polarized antenna through simple feeding structures for millimeter-wave AiP applications","authors":"Tzu-Ming Huang;Yi-Cheng Lin","doi":"10.1029/2024RS008042","DOIUrl":"https://doi.org/10.1029/2024RS008042","url":null,"abstract":"This paper presents a dual-polarized cavity-backed antenna designed for mm-wave applications, featuring simple feeding structures with a high-isolation for 60 GHz compact AiP applications. The dual-polarization design relies on two separate feed ports that excite two orthogonal modes within the same resonant cavity, achieving very high port isolation of up to 40 dB over the entire band. We conducted a detail analysis of the antenna, including its working principles and parametric studies. For verification, we fabricated an antenna test kit using standard printed process on substrates and measured the kit from the back-side of a GSG probing platform. The proposed antenna demonstrates a wide impedance bandwidth, stable radiation patterns, very low cross-polarization levels, and a high radiation efficiency. The co-located cavity-backed design ensures the compactness and facilitates easy integration with ICs in a very small AiP module. These features make the proposed antenna highly suitable for 60 GHz AiP applications, such as high-data-rate wireless communication and mmW polarimetric radar systems.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-15"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595808","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}
Guanjun Xu;Lianning Cai;Xianqiang Li;Yanli Shao;Zhaohui Song
During probe-to-Earth superior conjunction, deep space communication channels will suffer from solar scintillation, leading to amplitude attenuation of received signals. This study aims to obtain the channel state information (CSI) on deep space channels affected by solar scintillation. Classical least squares (LS) and minimum mean squared error (MMSE) methods are adopted to perform channel estimation and compensate for the channel fading. Simulation results indicate that under the effect of solar scintillation, performing channel estimation technology can significantly improve bit error rate (BER) performance compared to systems without CSI, and the MMSE algorithm outperforms the LS for both BER and normalized mean squared error (NMSE). In addition, we also find that pilot density, geometric parameters, and the outer scale of solar wind turbulence has great influence on the estimation performance.
在探测器与地球卓越会合期间，深空通信信道将受到太阳闪烁的影响，导致接收信号的振幅衰减。本研究旨在获取受太阳闪烁影响的深空信道的信道状态信息（CSI）。研究采用经典的最小二乘法（LS）和最小均方误差法（MMSE）进行信道估计，并对信道衰落进行补偿。仿真结果表明，在太阳闪烁的影响下，与没有 CSI 的系统相比，采用信道估计技术可以显著提高误码率（BER）性能，而 MMSE 算法在误码率和归一化均方误差（NMSE）方面都优于 LS 算法。此外，我们还发现先导密度、几何参数和太阳风湍流的外部尺度对估计性能有很大影响。
{"title":"Channel estimation for deep space communications under the effect of solar scintillation","authors":"Guanjun Xu;Lianning Cai;Xianqiang Li;Yanli Shao;Zhaohui Song","doi":"10.1029/2024RS008038","DOIUrl":"https://doi.org/10.1029/2024RS008038","url":null,"abstract":"During probe-to-Earth superior conjunction, deep space communication channels will suffer from solar scintillation, leading to amplitude attenuation of received signals. This study aims to obtain the channel state information (CSI) on deep space channels affected by solar scintillation. Classical least squares (LS) and minimum mean squared error (MMSE) methods are adopted to perform channel estimation and compensate for the channel fading. Simulation results indicate that under the effect of solar scintillation, performing channel estimation technology can significantly improve bit error rate (BER) performance compared to systems without CSI, and the MMSE algorithm outperforms the LS for both BER and normalized mean squared error (NMSE). In addition, we also find that pilot density, geometric parameters, and the outer scale of solar wind turbulence has great influence on the estimation performance.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-10"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595829","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 work, we analyze data collected by an HF transmitter/receiver radio link, operating as an oblique ionosonde between the McMurdo Station (transmitter) and South Pole Station (receiver) at 4.1, 5.1, 6.0, 6.4, and 7.2 MHz between 28 February and 14 March 2019. To help contextualize the link's data we have performed numerical raytrace simulations to help understand the observations. By considering both the data and simulations, we have identified both single- and two-hop E- and F-region propagation modes in the data, where the multi-hop modes were observed in the hours around sunrise and sunset in the 4.1 and 5.1 MHz channels. This is an unexpected result given the accepted wisdom that multi-hop modes, which require a ground scatter component, cannot be supported in Antarctica because of the highly absorptive ice covering much of the continent. Our results show that multi-hop propagation modes can be supported in the region under specific ionospheric conditions—around sunrise and sunset—if the mode's ground scatter component is collocated with the Transantarctic Mountains. The mountains are located along the great-circle path between the link's transmitter and receiver. However, the combination of favorable ionospheric and ground scattering conditions makes the detection of the multi-hop mode a rare occurrence in the data set analyzed here. These findings are critical to data analysis efforts of any current or future oblique ionosonde systems operating in Antarctica and other regions such as the Arctic.
{"title":"An assessment of HF radio wave propagation in antarctica for a radio link between McMurdo and south pole station","authors":"B. Liu;G. W. Perry;A. T. Chartier","doi":"10.1029/2022RS007632","DOIUrl":"https://doi.org/10.1029/2022RS007632","url":null,"abstract":"In this work, we analyze data collected by an HF transmitter/receiver radio link, operating as an oblique ionosonde between the McMurdo Station (transmitter) and South Pole Station (receiver) at 4.1, 5.1, 6.0, 6.4, and 7.2 MHz between 28 February and 14 March 2019. To help contextualize the link's data we have performed numerical raytrace simulations to help understand the observations. By considering both the data and simulations, we have identified both single- and two-hop E- and F-region propagation modes in the data, where the multi-hop modes were observed in the hours around sunrise and sunset in the 4.1 and 5.1 MHz channels. This is an unexpected result given the accepted wisdom that multi-hop modes, which require a ground scatter component, cannot be supported in Antarctica because of the highly absorptive ice covering much of the continent. Our results show that multi-hop propagation modes can be supported in the region under specific ionospheric conditions—around sunrise and sunset—if the mode's ground scatter component is collocated with the Transantarctic Mountains. The mountains are located along the great-circle path between the link's transmitter and receiver. However, the combination of favorable ionospheric and ground scattering conditions makes the detection of the multi-hop mode a rare occurrence in the data set analyzed here. These findings are critical to data analysis efforts of any current or future oblique ionosonde systems operating in Antarctica and other regions such as the Arctic.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-17"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595781","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}
Muhammad Fitra Zambak;Safpbri Johari;Mohd Najib Mohd Yassin;Arif Marwardi Ismail;Abdullah Alghaihab
This paper addresses the limited gain of conventional Antipodal Vivaldi Antenna (AVA) at higher frequencies. We propose a novel Metamaterial Lens Vivaldi Antenna (MLVA) design that overcomes this limitation by integrating an exponentially tapered antenna lens and a strategically placed Near Zero Refractive Index (NRZI) metamaterial lattice. The MLVA achieves exceptional wideband performance with a — 3 dB gain bandwidth exceeding 148.6% from 3.7 to 25 GHz. The result demonstrates a peak realized gain of 11.8 dBi at 11.2 GHz, compared to 9.1 dBi conventional AVA, especially beyond 5 GHz. The compact MLVA design measures only 120 × 78 × 1.524 mm 3 (1.48 × 0.96 × 0.0188λ 03 ) λ 0 where free-space wavelength is the lowest frequency and is fabricated on RO4350 B substrate with a 50-Ω SMA connector. Key features of the design include exponential flaring, and trapezoidal lens geometries chosen for their inherent ability to effectively collimate and direct the spherical wavefront. The incorporation of a dielectric lens and metasurface further enhances gain and Front-to-Back Ratio (FBR) by directing the majority of energy in the end-fire direction. Experimental results validate the effectiveness of the proposed design, confirming simulation predictions. These outstanding characteristics make the MLVA a promising candidate for diverse wireless communication and radar applications demanding high data rates across a broad frequency range.
{"title":"Ultra-wide band antipodal vivaldi antenna using metasurface lens for gain and front-to-back ratio (FBR) improvement","authors":"Muhammad Fitra Zambak;Safpbri Johari;Mohd Najib Mohd Yassin;Arif Marwardi Ismail;Abdullah Alghaihab","doi":"10.1029/2024RS008115","DOIUrl":"https://doi.org/10.1029/2024RS008115","url":null,"abstract":"This paper addresses the limited gain of conventional Antipodal Vivaldi Antenna (AVA) at higher frequencies. We propose a novel Metamaterial Lens Vivaldi Antenna (MLVA) design that overcomes this limitation by integrating an exponentially tapered antenna lens and a strategically placed Near Zero Refractive Index (NRZI) metamaterial lattice. The MLVA achieves exceptional wideband performance with a — 3 dB gain bandwidth exceeding 148.6% from 3.7 to 25 GHz. The result demonstrates a peak realized gain of 11.8 dBi at 11.2 GHz, compared to 9.1 dBi conventional AVA, especially beyond 5 GHz. The compact MLVA design measures only 120 × 78 × 1.524 mm\u0000<sup>3</sup>\u0000 (1.48 × 0.96 × 0.0188λ\u0000<inf>0</inf>\u0000<sup>3</sup>\u0000) λ\u0000<inf>0</inf>\u0000 where free-space wavelength is the lowest frequency and is fabricated on RO4350 B substrate with a 50-Ω SMA connector. Key features of the design include exponential flaring, and trapezoidal lens geometries chosen for their inherent ability to effectively collimate and direct the spherical wavefront. The incorporation of a dielectric lens and metasurface further enhances gain and Front-to-Back Ratio (FBR) by directing the majority of energy in the end-fire direction. Experimental results validate the effectiveness of the proposed design, confirming simulation predictions. These outstanding characteristics make the MLVA a promising candidate for diverse wireless communication and radar applications demanding high data rates across a broad frequency range.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-15"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595828","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 paper, we present a review and classification of the published works on the use of Electromagnetic Time Reversal (EMTR)-based methods to locate landmines. Different approaches for landmine localization using EMTR are investigated. Specifically, the classical time-domain EMTR, iterative EMTR, EMTR-DORT (Décomposition de l’Opérateur du Retournement Temporel), and EMTR-MUSIC (Multiple SIgnal Classification) are implemented using different numerical techniques. The main properties of the mentioned EMTR-based approaches are reviewed and the TR-MUSIC method is selected as the most promising approach for the problem of interest, among all the reviewed methods. In the TR-MUSIC method, the transfer matrix is calculated in the first step. Then, the singular value decomposition of the transfer matrix is performed. In the last step, the location of the landmines is obtained through the evaluation of the pseudospectrum. As opposed to other EMTR-based techniques, TR-MUSIC features very high resolution (in the order of 1/10 or higher) with a reasonable number of sensors, allowing the detection of multiple closely spaced targets.
在本文中，我们对已发表的有关使用基于电磁时间反演（EMTR）的地雷定位方法的著作进行了综述和分类。本文研究了利用 EMTR 进行地雷定位的不同方法。具体而言，利用不同的数值技术实现了经典时域 EMTR、迭代 EMTR、EMTR-DORT（Décomposition de l'Opérateur du Retournement Temporel）和 EMTR-MUSIC（多重信号分类）。对上述基于 EMTR 的方法的主要特性进行了评述，在所有评述方法中，TR-MUSIC 方法被选为最有希望解决相关问题的方法。在 TR-MUSIC 方法中，第一步是计算转移矩阵。然后，对传递矩阵进行奇异值分解。最后一步，通过评估伪谱获得地雷的位置。与其他基于 EMTR 的技术相比，TR-MUSIC 具有极高的分辨率（1/10 或更高）和合理的传感器数量，可探测多个紧密间隔的目标。
{"title":"Landmine detection using electromagnetic time reversalbased methods: 1. classical TR, iterative TR, DORT and TR-MUSIC","authors":"Hamidreza Karami;André Koch;Carlos Romero;Marcos Rubinstein;Farhad Rachidi","doi":"10.1029/2024RS007971","DOIUrl":"https://doi.org/10.1029/2024RS007971","url":null,"abstract":"In this paper, we present a review and classification of the published works on the use of Electromagnetic Time Reversal (EMTR)-based methods to locate landmines. Different approaches for landmine localization using EMTR are investigated. Specifically, the classical time-domain EMTR, iterative EMTR, EMTR-DORT (Décomposition de l’Opérateur du Retournement Temporel), and EMTR-MUSIC (Multiple SIgnal Classification) are implemented using different numerical techniques. The main properties of the mentioned EMTR-based approaches are reviewed and the TR-MUSIC method is selected as the most promising approach for the problem of interest, among all the reviewed methods. In the TR-MUSIC method, the transfer matrix is calculated in the first step. Then, the singular value decomposition of the transfer matrix is performed. In the last step, the location of the landmines is obtained through the evaluation of the pseudospectrum. As opposed to other EMTR-based techniques, TR-MUSIC features very high resolution (in the order of 1/10 or higher) with a reasonable number of sensors, allowing the detection of multiple closely spaced targets.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-13"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595779","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}
Stochastic analysis of the absorbed power density (APD) on skin surface exposed to radiation of halfwave dipole at 10, 30 and 90 GHz and for different antenna-body distances is presented. Skin tissue is modeled as a half-space consisting of one layer (skin) or three layers (skin, fat and muscle) whose permittivities and conductivities are uncertain. Deterministic part is based on numerical solution of Pocklington equation via Galerkin Bubnov Indirect Boundary Element method (GB-IBEM) and numerical integration of the corresponding field integrals. Uncertainty from tissue electric parameters is propagated to APD via nonintrusive Stochastic Collocation method (SCM) in order to compute stochastic moments of APD. For 1-layered model APD stochastic moments are computed with 3 deterministic simulations. On the other hand APD mean and variance for 3 layered model are successfully computed with 13 deterministic simulations while skewness and kurtosis require 85 deterministic simulations. The ratio of APD standard deviation and mean decreases with frequency thus indicating that the uncertainty in the tissue electric properties has smaller effect on APD uncertainty at higher frequencies. Finally, sensitivity analysis carried out for both 1-layered and 3-layered models indicates the same conclusions. At 10 GHz skin permittivity and conductivity are the two most important parameters. However, as frequency increases the impact of skin conductivity prevails. This indicates that in frequency range 10-90 GHz the APD uncertainty quantification and sensitivity analysis can be carried out by using only 2-dimensional stochastic model.
{"title":"Stochastic analysis of epithelial/absorbed power density in multilayered planar skin model with uncertain tissue electric properties","authors":"Anna Susnjara Nejasmic;Dragan Poljak","doi":"10.1029/2024RS007988","DOIUrl":"https://doi.org/10.1029/2024RS007988","url":null,"abstract":"Stochastic analysis of the absorbed power density (APD) on skin surface exposed to radiation of halfwave dipole at 10, 30 and 90 GHz and for different antenna-body distances is presented. Skin tissue is modeled as a half-space consisting of one layer (skin) or three layers (skin, fat and muscle) whose permittivities and conductivities are uncertain. Deterministic part is based on numerical solution of Pocklington equation via Galerkin Bubnov Indirect Boundary Element method (GB-IBEM) and numerical integration of the corresponding field integrals. Uncertainty from tissue electric parameters is propagated to APD via nonintrusive Stochastic Collocation method (SCM) in order to compute stochastic moments of APD. For 1-layered model APD stochastic moments are computed with 3 deterministic simulations. On the other hand APD mean and variance for 3 layered model are successfully computed with 13 deterministic simulations while skewness and kurtosis require 85 deterministic simulations. The ratio of APD standard deviation and mean decreases with frequency thus indicating that the uncertainty in the tissue electric properties has smaller effect on APD uncertainty at higher frequencies. Finally, sensitivity analysis carried out for both 1-layered and 3-layered models indicates the same conclusions. At 10 GHz skin permittivity and conductivity are the two most important parameters. However, as frequency increases the impact of skin conductivity prevails. This indicates that in frequency range 10-90 GHz the APD uncertainty quantification and sensitivity analysis can be carried out by using only 2-dimensional stochastic model.","PeriodicalId":49638,"journal":{"name":"Radio Science","volume":"59 10","pages":"1-15"},"PeriodicalIF":1.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142595830","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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