Propagation characteristics of time reversal pulsed electromagnetic waves in double negative materials

Zhao, Deshuang; Wen-Jun, Yue; Min, Yu; Zhang, Shengxue

doi:10.7498/aps.61.074102

Cited by 3 publications

(2 citation statements)

References 15 publications

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“…So the TR technique can adaptively compensate for the phase generated by the channel and focus signals. Since the TR technique was introduced into electromagnetics (Lerosey et al., 2004), it has been widely used in the fields of super‐resolution focusing (Ding et al., 2013; Ge et al., 2011; Lerosey et al., 2007), high‐precision positioning (Li, Liu, Zhao, & Hu, 2019; Liang, 2020; Zhou et al., 2014, 2015), wireless power transmission (An et al., 2021; Ku et al., 2016; Li, Liu, Zhang, et al., 2019; Liu et al., 2011; Park & Hong, 2020, 2021; Y. Wang et al., 2021; Yang et al., 2021; Zhao, Yue, et al., 2012), spatial power combination (Q. Chen et al., 2015; Tian, 2019; Z. Wang et al., 2019; Zhong & Liao, 2016), and so on. In addition, Wang's team has also carried out a series of research on TR technology in shaping electromagnetic fields (Z. Chen et al., 2021; Li, Zhao, et al., 2019), wireless communication (Jin et al., 2013; Z. Wang et al., 2019; Zhao et al., 2014), beam‐steering (Zhao, Jin, et al., 2012), and other fields.…”

Section: Introductionmentioning

confidence: 99%

Influence of Time‐Varying Atmospheric Channel on Time Reversal Spatial Power Combination of Sparse Array on Ground

Zhao

2023

Radio Science

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The spatial power combination based on the time reversal (TR) technique is severely affected by the time‐varying characteristics of channels. In this paper, a mathematical model of TR power combination in the slowly time‐varying atmospheric channel and the concept of channel time‐varying factor are proposed to study the feasibility of this technique for spatial power combination in incompletely reciprocal channels. Combining the theoretical analysis and Monte Carlo simulations, we analyze the relationship between the power combination efficiency and the permittivity of the time‐varying atmospheric channel, which follows a normal distribution. The results indicate that the power combination efficiency of the TR technique will be lower than that of the completely reciprocal channel if the atmospheric channel is slowly varied, and the faster the channel changes, the lower the efficiency becomes. In order to keep the power combination efficiency above 50%, the channel time‐varying factor needs to be less than about 54.3% of the signal period. And when it takes more than 90%, the signals radiated by each antenna have been completely incoherent at target point. Different from the short‐distance power combination, when the target point is far away and at a high altitude, the time‐variability of the atmosphere over such a huge area is not negligible, so the power combination efficiency will be also severely affected. The mathematical model and results of this study can provide a theoretical basis for further research of long‐distance spatial power combination based on the TR technology and error estimation in related engineering design.

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Section: Introductionmentioning

confidence: 99%

Influence of Time‐Varying Atmospheric Channel on Time Reversal Spatial Power Combination of Sparse Array on Ground

Zhao

2023

Radio Science

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“…[5,6] Recently, because of its adaptive focusing property, the time-reversal technique has been used in wireless communication, [7][8][9][10][11] nondestructive testing, [12,13] object positioning, [14,15] object imaging, [16,17] and super-resolution focusing. [18][19][20][21] The focusing signals always show autocorrelation of the propagator in the time domain. This behavior allows the time-reversal waves to exhibit adaptive focusing.…”

Section: Introductionmentioning

confidence: 99%

The determination of the relative permittivity of periodic stratified media based on the iterative time-reversal method

et al. 2014

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Secure transmission mechanism based on time reversal over wireless multipath channels

Zhu¹,

Wang²,

Tian³

2018

Acta Phys. Sin.

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Broadband wireless communication is implemented primarily in a complicated environment. The complex environment with time-varying multi-path propagation characteristics will seriously affect the performance of communication. To solve the problem of insecurity in information transmission in wireless channels, in this paper a system is modeled by using the multi-input single output eavesdropping channel model and the security of information transmission through time reversal technology is ensured. Another problem is that the information focuses on the receiving point. Owing to the temporal and spatial focusing characteristics of the time reversal technology the information near the receiving point can be eavesdropped easily. To solve this problem, a secure transmission scheme based on time reversal technology with artificial noise interference on the transmitter side is proposed. One of the core technologies to solve this problem is to introduce the environment adaptive technique–time reversal in the wireless link. Further, the problem of a wiretap channel in physical layer security research has become a popular research topic in recent years. To solve the problems about the physical layer wiretap channel and multi-path fading in wireless channels, a novel concept combining time reversal technology with physical layer security technology is proposed. In this paper, a physical layer secure transmission scheme based on the joint time reversal technique and artificial noise at the sending end is proposed for the wireless multi-path channel. First, in a typical wiretap channel model the time reversal technique is used to improve the security of the information transmission process by using the properties of spatial and temporal focusing. It refers to the fact that information can be focused at a given moment and in space. Second, as the information is easily eavesdropped near the focus point, artificial noise is added to the sending end to disrupt the ability of the eavesdropper to eavesdrop. The artificial noise has no effect on legitimate user due to the use of null-space artificial noise in legitimate user. Based on this scheme, a closed expression, such as secure signal-to-interference and signal-to-noise ratio, an achievable secrecy rate and bit error rate are obtained, and the influences of the number of antennas, signal-to-noise ratio, and artificial noise are analyzed. The theoretical analysis and simulation results show that the proposed scheme has a higher secrecy signal-to-noise ratio, a higher rate of secrecy, and a lower bit error rate of the legitimate user than the the existing physical layer security schemes.

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Propagation characteristics of time reversal pulsed electromagnetic waves in double negative materials

Cited by 3 publications

References 15 publications

Influence of Time‐Varying Atmospheric Channel on Time Reversal Spatial Power Combination of Sparse Array on Ground

Influence of Time‐Varying Atmospheric Channel on Time Reversal Spatial Power Combination of Sparse Array on Ground

The determination of the relative permittivity of periodic stratified media based on the iterative time-reversal method

Secure transmission mechanism based on time reversal over wireless multipath channels

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