scholarly journals JOINT AZIMUTH-ELEVATION/(-RANGE) ESTIMATION OF MIXED NEAR-FIELD AND FAR-FIELD SOURCES USING TWO-STAGE SEPARATED STEERING VECTOR-BASED ALGORITHM

2011 ◽  
Vol 113 ◽  
pp. 17-46 ◽  
Author(s):  
Junli Liang ◽  
Ding Liu ◽  
Xianju Zeng ◽  
Wenyi Wang ◽  
Jiulong Zhang ◽  
...  
Keyword(s):  
Near Field ◽  
Far Field ◽  
Range Estimation ◽  
Two Stage ◽  
Steering Vector ◽  
Elevation Range

scholarly journals Theoretical and Experimental Studies on the Signal Propagation in Soil for Wireless Underground Sensor Networks

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2580
Author(s):  
Hongwei Huang ◽  
Jingkang Shi ◽  
Fei Wang ◽  
Dongming Zhang ◽  
Dongmei Zhang
Keyword(s):  
Sensor Networks ◽  
Near Field ◽  
Path Loss ◽  
Far Field ◽  
Stage Model ◽  
Field Region ◽  
Experiment Data ◽  
Two Stage ◽  
Proposed Model ◽  
Wireless Underground Sensor Networks

Wireless Underground Sensor Networks (WUSNs), an important part of Internet of things (IoT), have many promising applications in various scenarios. Signal transmission in natural soil undergoes path loss due to absorption, radiation, reflection and scattering. The variability and dynamic of soil conditions and complexity of signal attenuation behavior make the accurate estimation of signal path loss challenging. Two existing propagation models for predicting path loss are reviewed and compared. Friis model does not consider the reflection loss and is only applicable in the far field region. The Fresnel model, only applicable in the near field region, has not considered the radiating loss and wavelength change loss. A new two stage model is proposed based on the field characteristics of antenna and considers four sources of path loss. The two stage model has a different coefficient m in the near field and far field regions. The far field distance of small size antenna is determined by three criteria: 2 D2/λ, 5 D, 1.6 λ in the proposed model. The proposed two stage model has a better agreement with the field experiment data compared to Friis and Fresnel models. The coefficient m is dependent on the soil types for the proposed model in near field region. It is observed from experiment data that the m value is in the range of 0~0.20 for sandy soils and 0.433~0.837 for clayey silt.

Ambiguity-Function-Based Methods for Near-Field Source Localization

2012 ◽  
Vol 160 ◽  
pp. 395-399
Author(s):  
Xin Sun ◽  
Hong Jiang ◽  
Bo Wang
Keyword(s):  
Source Localization ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
High Accuracy ◽  
Ambiguity Function ◽  
Far Field ◽  
Range Estimation ◽  
Signal To Noise ◽  
Field Source ◽  
Stationary Signals

In this paper, the AD-MUSIC method for far-field source localization is introduced to near-field, a two-dimensional MUSIC method based on ambiguity function distribution is proposed. Further, a novel AD-ROOT-MUSIC method is proposed for near-field source localization which constructes two matrices based on ambiguity function. They both have high accuracy and resolution for the bearing and range estimation of non-stationary signals in the near field, even when the signal-to-noise ratio (SNR) is low. The effectivity of the methods are validated by simulations.

scholarly journals Mixed Far-Field and Near-Field Source Localization Algorithm via Sparse Subarrays

2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Jiaqi Song ◽  
Haihong Tao ◽  
Jian Xie ◽  
Chenwei Sun
Keyword(s):  
Near Field ◽  
Doa Estimation ◽  
Estimation Accuracy ◽  
Far Field ◽  
Localization Algorithm ◽  
Range Estimation ◽  
Field Source ◽  
Quarter Wavelength ◽  
Shift Invariance ◽  
Array Aperture

Based on a dual-size shift invariance sparse linear array, this paper presents a novel algorithm for the localization of mixed far-field and near-field sources. First, by constructing a cumulant matrix with only direction-of-arrival (DOA) information, the proposed algorithm decouples the DOA estimation from the range estimation. The cumulant-domain quarter-wavelength invariance yields unambiguous estimates of DOAs, which are then used as coarse references to disambiguate the phase ambiguities in fine estimates induced from the larger spatial invariance. Then, based on the estimated DOAs, another cumulant matrix is derived and decoupled to generate unambiguous and cyclically ambiguous estimates of range parameter. According to the coarse range estimation, the types of sources can be identified and the unambiguous fine range estimates of NF sources are obtained after disambiguation. Compared with some existing algorithms, the proposed algorithm enjoys extended array aperture and higher estimation accuracy. Simulation results are given to validate the performance of the proposed algorithm.

Magnetic Tag Antenna for UHF Near-field and Far-Field RFID Applications

2015 ◽  
Vol 5 (2) ◽  
pp. 119
Author(s):  
Mondher Dhaouadi ◽  
M. Mabrouk ◽  
T. Vuong ◽  
A. Ghazel
Keyword(s):  
Near Field ◽  
Far Field ◽  
Rfid Applications
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