Millimeter-wave(mm Wave) communications will be used in fifth-generation(5G) mobile communication systems, but they experience severe path loss and have high sensitivity to physical objects, leading to smaller cell ra...Millimeter-wave(mm Wave) communications will be used in fifth-generation(5G) mobile communication systems, but they experience severe path loss and have high sensitivity to physical objects, leading to smaller cell radii and complicated network architectures. A coverage extension scheme using large-scale antenna arrays(LSAAs) has been suggested and theoretically proven to be cost-efficient in combination with ultradense small cell networks. To analyze and optimize the LSAA-based network deployments, a comprehensive survey of recent advances in statistical mmWave channel modeling is first presented in terms of channel parameter estimation, large-scale path loss models, and small-scale cluster models. Next, the measurement and modeling results at two 5G candidate mmWave bands(e.g., 28 GHz and 39 GHz) are reviewed and compared in several outdoor scenarios of interest, where the propagation characteristics make crucial contributions to wireless network designs. Finally, the coverage behaviors of systems employing a large number of antenna arrays are discussed, as well as some implications on future mmWave cellular network designs.展开更多
In this letter, an integrated application of the prediction for radio wave propagation with the Geographic Information System (GIS) is presented and a real prediction system based on GIS is implemented.
This paper numerically investigates the radio wave scattering by the artificial acoustic disturbance in the atmospheric boundary layer. The numerical model is based on the finitedifference time-domain（FDTD） method f...This paper numerically investigates the radio wave scattering by the artificial acoustic disturbance in the atmospheric boundary layer. The numerical model is based on the finitedifference time-domain（FDTD） method for radio wave propagation and fluid simulation for atmospheric disturbance by acoustics waves. The characteristics of radio wave scattering propagation in the artificial acoustic perturbations are investigated by this numerical model. The numerical simulation results demonstrate that the radio wave propagation scattered by acoustic scatterer has the characteristic of forward tropospheric scatter. When the radio waves are scattered, they distribute in all directions; a majority of radio waves continues to propagate along the original direction, and only a small part of the energy is scattered. For the same acoustic scatterer, if we merely change the radio wave emission elevation, the horizontal spans of forward scattering radio wave packets centers gradually decrease with the increasing of emission elevations; and the energy of wave packets increases firstly and then decreases with launching elevation, reaching the maximum at a certain angle. If we merely change the wave emitting position, the horizontal spans decrease with the increasing of emission positions, and the energy of wave packets also increases firstly and then decreases with launch position, reaching the maximum at a certain position. This approach can be very promising for atmospheric scatter communications.展开更多
The characteristics of anomalous radio propagation in the frequency 1 - 30 MHz before and after the 2011 Tohoku-Oki earthquake are firstly revealed by using oblique ionograms for the pass from Wakkanai to Kokubunji wh...The characteristics of anomalous radio propagation in the frequency 1 - 30 MHz before and after the 2011 Tohoku-Oki earthquake are firstly revealed by using oblique ionograms for the pass from Wakkanai to Kokubunji which is closest to the epicenter. An oblique ionogram with a wavy-shape-trace was observed at 06:30 UTC on 11 March 2011 after the 2011 Tohoku-Oki earthquake. The velocity of northward-propagating disturbance caused this wavy-shape-trace is estimated to be 130 m/s. This wave-shape-trace shows very clear signature appearing in the oblique ionograms as the characteristic of strong ionospheric disturbances triggered by the earthquake. An oblique ionogram with a steep slopy-shape-trace was observed at 04:45 UTC on 11 March 2011 one hour before the 2011 Tohoku-Oki earthquake. This slopy-shape-trace is investigated as the signatures of preseismic ionospheric anomaly. This anomalous oblique ionogram with a slopy-shape-trace is examined with the slope ratio of virtual height to sweep-frequency, and the difference between monthly median foF2 and hourly value foF2 at Wakkanai and Kokubunji. These features appearing in oblique ionograms suggest that it is useful for studying the signatures of preseismic ionospheric anomaly.展开更多
It is an eternal topic to study the minimum loss under the maximum transmission distance and the practicality of radio propagation in the navigation of ships. The transmission loss by dividing it to Median medium atte...It is an eternal topic to study the minimum loss under the maximum transmission distance and the practicality of radio propagation in the navigation of ships. The transmission loss by dividing it to Median medium attenuation and Media attenuation correction factor is discussed. The Longley-Rice Model is introduced and improved;the correlation proportion of our model is work out. Then the reflection correction factor is calculated in the case of silent and turbulent ocean, which comes to the total loss and strength of the first reflection. The signal to noise ratio is explained and the relationship between various angle of incidence and correction factor are explored. According to fixed signal to noise ratio 14, the highest bounce frequency is got.展开更多
This research study represents an ongoing research effort on Unidentified Anomalous Phenomena (UAP) with a focus on anomalous propagation of radar echo returns, mirroring established theoretical constructs of gravitat...This research study represents an ongoing research effort on Unidentified Anomalous Phenomena (UAP) with a focus on anomalous propagation of radar echo returns, mirroring established theoretical constructs of gravitational effects on light, which occur at higher frequencies and shorter wavelengths within the Electromagnetic Spectrum. These influences are also illustrated through other technologies, including Light Detection and Ranging (LIDAR) and the chromatic effects captured by hyperspectral cameras. This research addresses the complexities of interpreting unusual propagation patterns, such as Long Delay Echoes (LDE) and unexpected Field Echoes (UFE), which disrupt the anticipated propagation and echo protocols, thereby challenging our understanding and comprehension of radio transmission norms that may be influenced by a form of quantum entanglement. The paper posits a significant and largely unexamined correlation between these phenomena in the context of UAP activity, highlighting the urgent need for further research and innovative strategies in navigation technology and environmental monitoring to investigate these potential occurrences, which have remained enigmatic for nearly a century. Radar signals are vulnerable to intricate dynamics that can lead to Unusual Field Echoes (UFE), resulting in emergent anomalies, such as Multiple echo returns and LDEs. This study employed a 3-centimeter marine-based X-band radar operating in two scan geometries and a portable short-range millimeter-wave Doppler radar system. An analysis of these radar echoes over a two-year study identified signal propagation that deviated from navigational standards on Plan Position Indicators (PPI). This paper explores and investigates the potential impacts of UAP on radar transmission routes. Examining these complexities makes a case for an enhanced understanding of the interactions between established technological factors and elusive aerial phenomena.展开更多
As an effective means to actively modify the ionosphere, chemical release can produce artificial ionospheric holes as a consequence of ionization depletion, which can greatly impact on radio wave propagation. In this ...As an effective means to actively modify the ionosphere, chemical release can produce artificial ionospheric holes as a consequence of ionization depletion, which can greatly impact on radio wave propagation. In this paper, on the basis of the pre-study results on ionospheric disturbances produced by some representative chemical releases, the radio waves propagation effects of ionospheric holes that are produced by two different release species, water （H2O） and sulfur hexafluoride （SF6）, had been investigated and simulated by the three-dimensional （3-D） numerical ray tracing. The results show that 1 the appearance of various artificial ionospheric holes can lead to certain decrease of critical frequency in the ionosphere, and 2 when the wave frequency exceeds the critical frequency, the rays should be multiple reflections or penetrate through the ionospheric hole and focus afterwards with the focus altitude elevated for higher frequencies. This work may provide the necessary theoretical support for chemical release experiments and the evaluation of radio wave propagation effects.展开更多
调频广播主要在甚高频(Very High Frequency,VHF)频段传输。VHF频段具有传播距离远、穿透力强、信号稳定等优势,但易受多种因素影响。基于此,首先介绍VHF频段的基本特点和调频广播信号的技术参数,其次介绍VHF频段调频广播信号传播的测...调频广播主要在甚高频(Very High Frequency,VHF)频段传输。VHF频段具有传播距离远、穿透力强、信号稳定等优势,但易受多种因素影响。基于此,首先介绍VHF频段的基本特点和调频广播信号的技术参数,其次介绍VHF频段调频广播信号传播的测量过程,最后从天线的设计和布置、调制、编码技术的应用等方面,提出改善VHF频段调频广播覆盖效果的策略。展开更多
基金supported in part by the National Natural Science Foundation of China under Grant No.61671145the Key R&D Program of Jiangsu Province of China under Grant BE2018121
文摘Millimeter-wave(mm Wave) communications will be used in fifth-generation(5G) mobile communication systems, but they experience severe path loss and have high sensitivity to physical objects, leading to smaller cell radii and complicated network architectures. A coverage extension scheme using large-scale antenna arrays(LSAAs) has been suggested and theoretically proven to be cost-efficient in combination with ultradense small cell networks. To analyze and optimize the LSAA-based network deployments, a comprehensive survey of recent advances in statistical mmWave channel modeling is first presented in terms of channel parameter estimation, large-scale path loss models, and small-scale cluster models. Next, the measurement and modeling results at two 5G candidate mmWave bands(e.g., 28 GHz and 39 GHz) are reviewed and compared in several outdoor scenarios of interest, where the propagation characteristics make crucial contributions to wireless network designs. Finally, the coverage behaviors of systems employing a large number of antenna arrays are discussed, as well as some implications on future mmWave cellular network designs.
文摘In this letter, an integrated application of the prediction for radio wave propagation with the Geographic Information System (GIS) is presented and a real prediction system based on GIS is implemented.
基金supported by the National Natural Science Foundation of China(412041114157414641774162)
文摘This paper numerically investigates the radio wave scattering by the artificial acoustic disturbance in the atmospheric boundary layer. The numerical model is based on the finitedifference time-domain（FDTD） method for radio wave propagation and fluid simulation for atmospheric disturbance by acoustics waves. The characteristics of radio wave scattering propagation in the artificial acoustic perturbations are investigated by this numerical model. The numerical simulation results demonstrate that the radio wave propagation scattered by acoustic scatterer has the characteristic of forward tropospheric scatter. When the radio waves are scattered, they distribute in all directions; a majority of radio waves continues to propagate along the original direction, and only a small part of the energy is scattered. For the same acoustic scatterer, if we merely change the radio wave emission elevation, the horizontal spans of forward scattering radio wave packets centers gradually decrease with the increasing of emission elevations; and the energy of wave packets increases firstly and then decreases with launching elevation, reaching the maximum at a certain angle. If we merely change the wave emitting position, the horizontal spans decrease with the increasing of emission positions, and the energy of wave packets also increases firstly and then decreases with launch position, reaching the maximum at a certain position. This approach can be very promising for atmospheric scatter communications.
文摘The characteristics of anomalous radio propagation in the frequency 1 - 30 MHz before and after the 2011 Tohoku-Oki earthquake are firstly revealed by using oblique ionograms for the pass from Wakkanai to Kokubunji which is closest to the epicenter. An oblique ionogram with a wavy-shape-trace was observed at 06:30 UTC on 11 March 2011 after the 2011 Tohoku-Oki earthquake. The velocity of northward-propagating disturbance caused this wavy-shape-trace is estimated to be 130 m/s. This wave-shape-trace shows very clear signature appearing in the oblique ionograms as the characteristic of strong ionospheric disturbances triggered by the earthquake. An oblique ionogram with a steep slopy-shape-trace was observed at 04:45 UTC on 11 March 2011 one hour before the 2011 Tohoku-Oki earthquake. This slopy-shape-trace is investigated as the signatures of preseismic ionospheric anomaly. This anomalous oblique ionogram with a slopy-shape-trace is examined with the slope ratio of virtual height to sweep-frequency, and the difference between monthly median foF2 and hourly value foF2 at Wakkanai and Kokubunji. These features appearing in oblique ionograms suggest that it is useful for studying the signatures of preseismic ionospheric anomaly.
文摘It is an eternal topic to study the minimum loss under the maximum transmission distance and the practicality of radio propagation in the navigation of ships. The transmission loss by dividing it to Median medium attenuation and Media attenuation correction factor is discussed. The Longley-Rice Model is introduced and improved;the correlation proportion of our model is work out. Then the reflection correction factor is calculated in the case of silent and turbulent ocean, which comes to the total loss and strength of the first reflection. The signal to noise ratio is explained and the relationship between various angle of incidence and correction factor are explored. According to fixed signal to noise ratio 14, the highest bounce frequency is got.
文摘This research study represents an ongoing research effort on Unidentified Anomalous Phenomena (UAP) with a focus on anomalous propagation of radar echo returns, mirroring established theoretical constructs of gravitational effects on light, which occur at higher frequencies and shorter wavelengths within the Electromagnetic Spectrum. These influences are also illustrated through other technologies, including Light Detection and Ranging (LIDAR) and the chromatic effects captured by hyperspectral cameras. This research addresses the complexities of interpreting unusual propagation patterns, such as Long Delay Echoes (LDE) and unexpected Field Echoes (UFE), which disrupt the anticipated propagation and echo protocols, thereby challenging our understanding and comprehension of radio transmission norms that may be influenced by a form of quantum entanglement. The paper posits a significant and largely unexamined correlation between these phenomena in the context of UAP activity, highlighting the urgent need for further research and innovative strategies in navigation technology and environmental monitoring to investigate these potential occurrences, which have remained enigmatic for nearly a century. Radar signals are vulnerable to intricate dynamics that can lead to Unusual Field Echoes (UFE), resulting in emergent anomalies, such as Multiple echo returns and LDEs. This study employed a 3-centimeter marine-based X-band radar operating in two scan geometries and a portable short-range millimeter-wave Doppler radar system. An analysis of these radar echoes over a two-year study identified signal propagation that deviated from navigational standards on Plan Position Indicators (PPI). This paper explores and investigates the potential impacts of UAP on radar transmission routes. Examining these complexities makes a case for an enhanced understanding of the interactions between established technological factors and elusive aerial phenomena.
基金Supported by the National Natural Science Foundation of China (60701020)the China Post-Doctoral Science Foundation (20080430988,200801321)the Fundamental Research Funds for the Central Universities (3103001)
文摘As an effective means to actively modify the ionosphere, chemical release can produce artificial ionospheric holes as a consequence of ionization depletion, which can greatly impact on radio wave propagation. In this paper, on the basis of the pre-study results on ionospheric disturbances produced by some representative chemical releases, the radio waves propagation effects of ionospheric holes that are produced by two different release species, water （H2O） and sulfur hexafluoride （SF6）, had been investigated and simulated by the three-dimensional （3-D） numerical ray tracing. The results show that 1 the appearance of various artificial ionospheric holes can lead to certain decrease of critical frequency in the ionosphere, and 2 when the wave frequency exceeds the critical frequency, the rays should be multiple reflections or penetrate through the ionospheric hole and focus afterwards with the focus altitude elevated for higher frequencies. This work may provide the necessary theoretical support for chemical release experiments and the evaluation of radio wave propagation effects.
文摘调频广播主要在甚高频(Very High Frequency,VHF)频段传输。VHF频段具有传播距离远、穿透力强、信号稳定等优势,但易受多种因素影响。基于此,首先介绍VHF频段的基本特点和调频广播信号的技术参数,其次介绍VHF频段调频广播信号传播的测量过程,最后从天线的设计和布置、调制、编码技术的应用等方面,提出改善VHF频段调频广播覆盖效果的策略。
