Chinese Research Institute of Radiowave Propagation

Qingdao, China

Chinese Research Institute of Radiowave Propagation

Qingdao, China
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Hao X.,Xidian University | Guo L.,Xidian University | Lin L.,Chinese Research Institute of Radiowave Propagation | Li Q.,Chinese Research Institute of Radiowave Propagation | Zhang Y.,Chinese Research Institute of Radiowave Propagation
ISAPE 2016 - Proceedings of the 11th International Symposium on Antennas, Propagation and EM Theory | Year: 2016

This study analyzed atmospheric ducts occurrence using radiosonde data obtained from 2005 to 2014 worldwide. The results show that the probabilities of ducting occurrence vary in different regions all over the world. The average year occurrences of surface ducts decrease gradually with the increase of latitude. And, comparisons of the duct distribution between the land and sea show that, the occurrence rate of marine is higher than that of land. At last, a comparison between ducting occurrences obtained from Rec. ITU-R P. 453-11 and this statistics has been made in this contribution. © 2016 IEEE.


Peng H.-Y.,Xidian University | Peng H.-Y.,Chinese Research Institute of Radiowave Propagation | Tao W.,Wuhan Naval University of Engineering | Tao W.,Naval Academy of Armament | And 2 more authors.
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2012

Extremely low frequency (ELF) propagation formulas for vertical electric dipole sources radiating in a spherical uniform earth-ionosphere cavity have been derived. These formulas have a range dependence characterized by either the Legendre function of the first kind of complex degree v and order zero or one of its first two derivatives. It is difficult to get the value of the Legendre function unless through appropriate approximations. In this paper, a new numerical integral method for the Legendre function is present. It is more efficient and accurate, and can be used in wider frequency band. The field excited vertical dipole at several frequencies are calculated through the numerical integral method. The fields calculated can image the physical phenomena of ELF propagation in earth-ionosphere cavity, and the frequencies of Schumem resonance is the same as previous researches. ©2012 by Editorial Department of Chinese Journal of Radio Science.


Li J.,Xidian University | Li J.,Chinese Research Institute of Radiowave Propagation | Shu T.,Xidian University | Lin L.,Chinese Research Institute of Radiowave Propagation | And 2 more authors.
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2013

An improved linear regression arithmetic of ground-based dual-frequency microwave radiometers to retrieve the atmosphere refractivity is put forward. It sets the dry item and wet item of the refractivity as the input of surface weather parameter. So it can reflect the relativity between the atmosphere refractivity and surface weather parameter better. Physical concept of the format is also clear. The simulation of historical data of Yichun, Harbin, Jinzhou, Taiyuan, Qingdao, Guangzhou and Sanya area has proved the validity of the arithmetic. The results show that the retrieving precision of the improved linear regression arithmetic is generally increased below 5 km especially for the atmosphere near ground. Copyright © 2013 by Editorial Department of Chinese Journal of Radio Science.


Peng H.,Xidian University | Pan W.,Chinese Research Institute of Radiowave Propagation | Guo L.,Xidian University
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2013

Extremely low frequency (ELF) propagation formulas for horizontal electric dipole sources radiating in a spherical uniform earth-ionosphere cavity have a range dependence characterized by either the Legendre function of the first kind of complex degree v and order zero or one of its first two derivatives. Using the iterative formulas of Legendre function, A new method is presented in this paper. The resulting waves are expressed as a superposition of T M and T E modes. In the near-filed range, the method of images is expected to be similar to the near fields of a dipole located on a flat finitely conducting, the far field is same as the result of Bannister (dir.+ind.) formulas. This shows that the method is accurate. The result of frequencies under 1 Hz show that the horizontal electric and magnetic components are independent of the azimuth φ, and the direction of horizontal electric components is parallel to the dipole axis in the isolines chart with distance, whereas, the direction of horizontal magnetic components is orthogonal to dipole axis. Copyright © 2013 by Editorial Department of Chinese Journal of Radio Science.


Dong H.,Chinese Research Institute of Radiowave Propagation | Yan Y.-B.,Chinese Research Institute of Radiowave Propagation | Li Q.-L.,Chinese Research Institute of Radiowave Propagation
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2010

The presented theoretical methods have difficulty in studying the SLF/ELF frequency band wave propagation characteristic in asymmetric ionosphere. In this paper, three-dimentional(3-D) finite-differece time-domain(FDTD) technique in spherical coordinate is applied to simulate the propagation of the electromagnetic fields excited by SLF/ELF horizontal electric dipole in spherical earth-ionosphere guide with asymmetric ionosphere(day-night asymmetry). The propagation characteristic of the electromagnetic wave are calcuated in the SLF/ELF frequency band on the ground. The results of the asymmetric ionosphere is more factual than that of the uniform ionosphere. Copyright©2010 by Editorial Department of Chinese Journal of Radio Science.


Li J.,Xidian University | Li J.,Chinese Research Institute of Radiowave Propagation | Guo L.,Xidian University | Lin L.,Chinese Research Institute of Radiowave Propagation | And 4 more authors.
Progress in Electromagnetics Research | Year: 2013

Ground-based microwave radiometer is the main device to remotely sense atmosphere passively which can detect the water vapor density, temperature, integral water vapor, etc. Because of the influence of cloud liquid water on the brightness temperature measured by microwave radiometer, the cloud needs to be modeled to retrieve the parameters of cloudy atmosphere. However, the difference between the cloud model and actual cloud may bring on some error in retrieval. Based on the relation between absorption coefficient of liquid water and frequency, a dual-frequency method of eliminating liquid water radiation which is not based on modeling cloud is put forward to retrieve the parameters of cloudy atmosphere. Historical radiosonde data are employed in the calculation of retrieval coefficients to profile the water vapor of cloudy atmosphere. The simulation and experiment results show that the dual-frequency method can eliminate the radiation of liquid water effectively and has a higher precision than conventional method. The integral water vapor in cloudy atmosphere is also retrieved by the dual-frequency method, and the precision is comparable with the method of modeling cloud.


Wang C.,Xidian University | Xu Z.-W.,Chinese Research Institute of Radiowave Propagation | Zhang M.,Xidian University | Chen C.,Chinese Research Institute of Radiowave Propagation
IET Conference Publications | Year: 2013

The interest in the use of space-borne SAR at low-frequency for collecting earth biomass information such as forest structure, soil moisture and soil type has been increased. It is crucial to understand the potential effects of radio wave propagation due to the ionospheric perturbation. In this paper, we present some effects of ionosphere on space-borne SAR imaging, especially the higher-order dispersion of the background and random scattering of irregularities are considered. Both the analysis and numerical simulation have been investigated to get some useful conclusions.


Wang C.,Xidian University | Zhang M.,Xidian University | Xu Z.-W.,Chinese Research Institute of Radiowave Propagation | Chen C.,Chinese Research Institute of Radiowave Propagation
2012 10th International Symposium on Antennas, Propagation and EM Theory, ISAPE 2012 | Year: 2012

In the past, most of the spaceborne synthetic aperture radars (SAR) operating at C-band or higher frequencies, and the ionospheric effects are negligible in these bands. Recently, the use of lower frequencies for measuring the foliage and ground penetration has been an increasing interest. However, the ionosphere is a highly dispersive medium, and can cause group delay and pulse broadening when the carrier frequency is low, such as P-band. Thus the range resolution in SAR imaging is degraded due to the ionospheric effects. And the irregularity of the ionosphere also can reduce the azimuthal resolution. Furthermore, the spaceborne SAR receiver would generate noise, which affects the quality of the echoes so as to SAR imaging. This paper presents both the analytical study and numerical simulation to investigate the ionospheric effects on SAR imaging with Gaussian white noise at P-band. © 2012 IEEE.


Zhang Y.,Xidian University | Zhang Y.,Chinese Research Institute of Radiowave Propagation | Xu X.,Chinese Research Institute of Radiowave Propagation | Wu Z.,Xidian University | Li X.,Chinese Research Institute of Radiowave Propagation
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2015

A new tow-component Gaussian model is presented on the basis of the comparative analysis of the impact of wind speed on sea clutter average reflectivity described by existing international models. Based on the measured sea clutter data of VV polarization at low grazing angles collected by a L-band radar at the yellow sea of china, the model was validated with precision analysis. The relationship between the model parameters and grazing angle is analyzed and the fitting parameters of the model is given. According to the results of data analysis, the proposed model can well capture the trend of the sea clutter amplitude with wind speed. This model is important for design of radar systems and radar sea clutter prediction. Copyright ©2015 by Editorial Department of Chinese Journal of Radio Science


Wang X.,Chinese Research Institute of Radiowave Propagation | Han X.,Chinese Research Institute of Radiowave Propagation | Peng H.,Xidian University | Chen Y.,Chinese Research Institute of Radiowave Propagation
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2014

In the region near the submarine, the static electromagnetic field may be generated by the electro-chemic current. The knowledge about the distribution of the field in the region is very important for finding the submarine. In this paper, the excited source of the field is idealized as a horizontal static electro dipole, based on the integral expressions of field excited by a low frequency electro dipole in the conducting half-space, taking the limit of ω→0, the integral expressions, of the field excited by the static electro dipole are obtained. These integral expressions related to Bessel-fanction may the simplified as a set of very simple analytical formula, and based on which the discussion is made and the space distribution of electromagnetic field is calculated. ©, Chinese Research Institute of Radiowave Propagation.

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