scholarly journals Study on the Detectability of the Sky-Surface Wave Hybrid Radar

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Hou Chengyu ◽  
Ke Guo ◽  
Shi Tiange ◽  
Wang Yuxin
Keyword(s):  
Electromagnetic Wave ◽  
Surface Wave ◽  
High Frequency ◽  
Propagation Loss ◽  
Sea Surface ◽  
Bistatic Radar ◽  
High Frequency Band ◽  
Reflection Point ◽  
Ionospheric Height ◽  
Radar Equation

Working in the HF (high-frequency) band and the transmitter and receiver locating separately, the sky-surface wave hybrid radar both has the capabilities of the OTHR (over-the-horizon radar) and the advantage of the bistatic radar. As the electromagnetic wave will be disturbed by the ionosphere, interfered by the sea clutter and attenuated by the sea surface, the detectability of this radar system is more complex. So, in this paper, we will discuss the problem detailedly. First of all, the radar equation is deduced based on the propagation of the electromagnetic wave. Then, how to calculate the effect of the ionosphere and the propagation loss is discussed. And an example based on the radar equation is given. At last, the ambiguity function is used to analyze the range and velocity resolution. From the result, we find that the resolution has relation with the location of the target and the height of reflection point of the ionosphere. But compared with the location, the effect of the ionospheric height can be ignored.

scholarly journals Observation of Zenneck-Like Waves over a Metasurface Designed for Launching HF Radar Surface Wave

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Florent Jangal ◽  
Nicolas Bourey ◽  
Muriel Darces ◽  
François Issac ◽  
Marc Hélier
Keyword(s):  
Surface Wave ◽  
High Frequency ◽  
Dielectric Medium ◽  
Hf Radar ◽  
Dielectric Slab ◽  
High Frequency Band ◽  
High Attenuation ◽  
Wave Radar ◽  
Infrared Method ◽  
Constant Interest

Since the beginning of the 20th century a controversy has been continuously revived about the existence of the Zenneck Wave. This wave is a theoretical solution of Maxwell’s equations and might be propagated along the interface between the air and a dielectric medium. The expected weak attenuation at large distance explains the constant interest for this wave. Notably in the High Frequency band such a wave had been thought as a key point to reduce the high attenuation observed in High Frequency Surface Wave Radar. Despite many works on that topic and various experiments attempted during one century, there is still an alternation of statements between its existence and its nonexistence. We report here an experiment done during the optimisation of the transmitting antennas for Surface Wave Radars. Using an infrared method, we visualize a wave having the structure described by Zenneck above a metasurface located on a dielectric slab.

scholarly journals The Vertical Ionosphere Parameters Inversion for High Frequency Surface Wave Radar

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Xuguang Yang ◽  
Changjun Yu ◽  
Aijun Liu ◽  
Linwei Wang ◽  
Taifan Quan
Keyword(s):  
Surface Wave ◽  
High Frequency ◽  
Plasma Frequency ◽  
Hot Spot ◽  
Research Area ◽  
F Region ◽  
Wave Radar ◽  
Parameters Inversion ◽  
Radar Equation ◽  
Field Aligned Irregularities

High Frequency Surface Wave Radar (HFSWR), which is currently applied in over-the-horizon detection of targets and sea states remote sensing, can receive a huge mass of ionospheric echoes, making it possible for the ionospheric clutter suppression to become a hot spot in research area. In this paper, from another perspective, we take the ionospheric echoes as the signal source rather than clutters, which provides the possibility of extracting information regarding the ionosphere region and explores a new application field for HFSWR. Primarily, pretreatment of threshold segmentation as well as connected region generation is used in the Range-Doppler (R-D) Spectrum to extract the ionospheric echoes. Then, electron density and plasma frequency of field aligned irregularities (FAIs) caused by plasma instabilities in the F region are obtained by the coherent backscattered radar equation. The plasma drift velocity of FAIs can also be estimated from Doppler shift. Ultimately, the effectiveness of inversion is verified by comparing with IRI2012.

ИССЛЕДОВАНИЯ АКУСТИЧЕСКИХ ХАРАКТЕРИСТИК ВЕРХНЕГО СЛОЯ МОРЯ МЕТОДОМ МНОГОЧАСТОТНОГО АКУСТИЧЕСКОГО ЗОНДИРОВАНИЯ

2020 ◽  
Author(s):  
V.A. Bulanov ◽  
I.V. Korskov ◽  
A.V. Storozhenko ◽  
S.N. Sosedko
Keyword(s):  
High Frequency ◽  
Wave Motion ◽  
High Spatial Resolution ◽  
Wind Waves ◽  
Acoustic Parameter ◽  
Sea Surface ◽  
Near Surface ◽  
Acoustical Properties ◽  
Acoustic Spectroscopy ◽  
Sea Bottom

Описано применение акустического зондирования для исследования акустических характеристик верхнего слоя моря с использованием широкополосных остронаправленных инвертированных излучателей,устанавливаемых на дно. В основу метода положен принцип регистрации обратного рассеяния и отраженияот поверхности моря акустических импульсов с различной частотой, позволяющий одновременно измерятьрассеяние и поглощение звука и нелинейный акустический параметр морской воды. Многочастотное зондирование позволяет реализовать акустическую спектроскопию пузырьков в приповерхностных слоях моря,проводить оценку газосодержания и получать данные о спектре поверхностного волнения при различных состояниях моря вплоть до штормовых. Применение остронаправленных высокочастотных пучков ультразвукапозволяет разделить информацию о планктоне и пузырьках и определить с высоким пространственным разрешением структуру пузырьковых облаков, образующихся при обрушении ветровых волн, и структуру планктонных сообществ. Участие планктона в волновом движении в толще морской воды позволяет определитьпараметры внутренних волн спектр и распределение по амплитудам в различное время.This paper represents the application of acoustic probingfor the investigation of acoustical properties of the upperlayer of the sea using broadband narrow-beam invertedtransducers that are mounted on the sea bottom. Thismethod is based on the principle of the recording of thebackscattering and reflections of acoustic pulses of differentfrequencies from the sea surface. That simultaneouslyallows measuring scattering and absorption of the soundand non-linear acoustic parameter of seawater. Multifrequencyprobing allows performing acoustic spectroscopy ofbubbles in the near-surface layer of the sea, estimating gascontent, and obtaining data on the spectrum of the surfacewaves in various states of the sea up to a storm. Utilizationof the high-frequency narrow ultrasound beams allows us toseparate the information about plankton and bubbles and todetermine the structure of bubble clouds, created during thebreaking of wind waves, along with the structure of planktoncommunities with high spatial resolution. The participationof plankton in the wave motion in the seawater columnallows determining parameters of internal waves, such asspectrum and distribution of amplitudes at different times.

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